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Relatore Istituto Location Referente Oato Titolo Data e ora Abstract
Dr. Filippo D'Ammando Universita` di Bologna e INAF-IRA Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Claudia Raiteri Relativistic jets in the Fermi-LAT sky: a different perspective 2016-11-23 11:00:00 Link You Tube abstract
The Fermi Gamma-ray Space Telescope with its main instrument onboard, the Large Area Telescope, opened a new era in the study of high-energy emission from Active Galactic Nuclei. Thanks to its high sensitivity, large field of view and sky survey operating mode the Fermi-LAT has detected several hundred of AGN. Although the large majority of these AGN are blazars, other types of gamma-ray emitting AGN such as radio galaxies and narrow-line Seyfert 1 galaxies have been detected. When combined with contemporaneous ground- and space-based observations, Fermi-LAT achieves its full capability to characterize the jet structure and the emission mechanisms at work in radio-loud AGN. In this talk I will discuss the radio-to-gamma-rays properties of blazars, radio galaxies, and narrow-line Seyfert 1 galaxies, highlighting major findings and open questions regarding the physics of AGN in the Fermi era.
Dr. Joao Faria University of Porto - Institute of Astrophysics and Space Sciences (Portugal) Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Alessandro Sozzetti A fundamental test of planet formation: searching for low-mass planets around metal-poor stars 2016-10-20 11:00:00 Seminar Link You Tube abstract
Stellar metallicity and planet formation are intimately linked. Theoretical work based on the core accretion model predicts that planets in the Neptune-mass regime should be common around stars with a wide range of metallicities, while giant planets should be more common around metal-rich stars. But the existence of a planet-metallicity relation for low-mass planets is not yet fully confirmed and quantified. We have been using HARPS observations to study a sample of moderately metal-poor stars. Our goal is to detect low-mass planets, in the Earth and Neptune mass regimes, and estimate their frequency around low-metallicity stars. I will present the results of this decade-long search, explain the difficulties that stellar activity poses for planet detection and show how the small number of planets detected so far in our sample is challenging the predictions from the core-accretion formation model.
Prof.ssa Catia Grimani University of Urbino - Department of Basic Science and Fundamentals Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Daniele Telloni Variazioni a corto termine dei raggi cosmici galattici ed evoluzione dei flussi di particelle solari di alta energia a bordo degli interferometri spaziali per onde gravitazionali. 2016-10-11 11:00:00 Seminar Link You Tube abstract
La recente scoperta delle onde gravitazionali e il successo della missione LISA Pathfinder renderanno più brevi i tempi per la costruzione e la messa in orbita degli interferometri finalizzati alla rivelazione di onde gravitazionali di prima e, possibilmente, seconda generazione. Queste missioni avranno a bordo dei rivelatori di particelle ad alto tasso di conteggio (0.067 Hz) che permetteranno di studiare il flusso integrale dei raggi cosmici di origine galattica e solare ad energie > 70 MeV/n. Queste caratteristiche, se pur determinate dalla necessità di monitorare il rilascio di carica sulle masse di test in caduta libera, risultano ottimali per lo studio delle variazioni a corto termine dei raggi cosmici galattici e l'evoluzione dei flussi di particelle solari di alta energia. eLISA e gli interferometri di seconda generazione consentiranno di studiare la dinamica di eventi di SEPs (Solar Energetic Particles) a piccoli angoli in longitudine sull'eclittica. In particolare, per eLISA è prevista una traiettoria "drift away" fino a 50 milioni di chilometri dalla Terra in 4 anni di missione e 65 in 6 anni di missione. A nostra conoscenza, nessun altro esperimento è previsto effettuare misure simili.
Dr. Carnerero Maribel INAF-OATo (Italy), IAC (Spain), Universidad de La Laguna (Spain) Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Claudia Raiteri Understanding blazar emission through multifrequency observations 2016-10-03 11:00:00 Seminar Link You Tube abstract
I will present the results of my PhD thesis, whose heart is the study of the multifrequency behaviour of a very special family of active galactic nuclei (AGNs) called blazars. The emission of these sources is generally dominated by non-thermal radiation from a plasma jet, making them the best candidates to investigate the properties of jets in AGNs. We analysed the flux and broad-band spectral variability of these objects from radio to the gamma rays. The radio, optical and near-infrared data were mostly obtained thanks to the Whole Earth Blazar Telescope (WEBT) Collaboration and Steward Observatory blazar spectropolarimetric monitoring, while high-energy data come from space observatories. In particular, ultraviolet and X-ray data were taken from Swift and gamma-ray data from Fermi. Multifrequency light curves allowed us to investigate the variability properties of these objects on different time scales, the correlation between flux changes in the different bands and possible time delays. From these results we inferred which are the most plausible physical mechanisms for blazar emission and the jet structure. From this collection of multifrequency data we can determine the energy spectral distribution (SED). Observing simultaneously at different frequencies and in different brightness states, we can detect whether there are emission contributions that are not coming from the jet, but from the AGN nucleus (accretion disk, broad line region, dusty torus), which helps us to understand the relation between blazars and other types of AGNs. This is a challenging topic since very high-quality data are needed, especially at ultraviolet frequencies, i.e. in a spectral region strongly affected by Galactic absorption. Once we have built light curves and SEDs we use them to test different jet models proposed to describe blazar emission and variability. Recently, a lot of observing effort has been devoted in providing polarimetric data in order to obtain information on the behaviour of the magnetic field. We analyzed a wide dataset of polarimetric data on several blazars to identify characteristic properties. We found a variety of behaviours, some of them ordered but the majority of them resulting in a chaotic trend. Indeed, it is very likely that turbulence affects the magnetic field most of the time.
Prof. Piero Galeotti Dipartimento di Fisica, INFN Torino Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Alberto Cora Novità dalla supernova 1987A 2016-06-15 11:00:00 Invited seminar Link You Tube abstract
La supernova 1987A, esplosa nelle Grandi Nubi di Magellano, venne scoperta a occhio nudo il 24 Febbraio di quell'anno dall'astronomo canadese Ian Shelton all'Osservatorio di Las Campanas in Cile. Si tratta dell'unica supernova visibile ad occhio nudo dopo quella del 1604 scoperta da Keplero. Recenti osservazioni del remnant di SN 1987A fatte con il satellite NuSTAR (Nuclear Spectroscopic Telescope Array, lanciato dalla NASA nel Giugno 2012 per lo studio del cielo nei raggi X) indicano che il collasso del core, da cui si originò questa supernova, fu fortemente asimmetrico. In particolare, l'analisi ad alta risoluzione delle righe del 44Ti mostra un'asimmetria a grande scala dell'esplosione, nel senso che la stella esplose espellendo il materiale in una direzione e il core in un'altra. L'asimmetria dell'esplosione è un requisito essenziale a favore dei modelli di esplosione in due stadi, suggeriti poco dopo l'esplosione per poter interpretare i dati sperimentali di tutti i laboratori sotterranei tra cui, in particolare, quello del Monte Bianco. In questo seminario vengono discusse le implicazioni del risultato di Nustar, pubblicato su Science nel 2015, riguardanti i risultati di tutti gli esperimenti attivi al momento dell'esplosione e non solo di quelli che di solito vengono citati perchè in accordo con il cosidetto modello standard di collasso gravitazionale, che trascura del tutto l'effetto della rotazione del core che può produrne la frammentazione.
Prof. Marco Bersanelli Università di Milano Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Aldo Bonomo The early universe as seen by the Planck space mission 2016-04-27 11:00:00 Invited seminar Link You Tube abstract
The cosmic microwave background (CMB) represents a unique window on the early universe as it directly probes the gravitational seeds from which all cosmic structure formed. The ESA Planck mission, launched in 2009, measured the CMB fluctuations over the whole sky, both in temperature and in polarization, with an unprecedented combination of angular resolution (5-33 arcmin), sensitivity (ΔT/T = 2 x 10-6), frequency range (30 to 857 GHz), and calibration accuracy (0.1%). Recently the Planck Collaboration has released the analysis of the full mission data. The results provide a spectacular confirmation of the basic ΛCDM model and yield estimates of the main cosmological parameters (including dark matter density, baryon density, primordial perturbations spectral index, Hubble constant, curvature, neutrino masses, optical depth, age of the universe) with high accuracy. The Galactic emission from interstellar dust and synchrotron has been mapped with great accuracy, as well as the extragalactic emission from clusters of galaxies through the SZ effect. A joint analysis of the Planck and Bicep2 data currently provide the best limits to primordial B-mode polarization predicted by inflationary models.
Dr. Alessandro Nagar IHES Bures-sur-Yvette, France Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Mariateresa Crosta Gravitational waves from coalescing compact binaries: interfacing analytical and numerical techniques 2016-04-07 11:00:00 Invited seminar Link You Tube abstract
I will report on recent results about the analytical effective one body (EOB) approach to the general-relativistic two-body dynamics and its completion using numerical relativity (NR) simulations. I will discuss three physical systems: (i) coalescence of (spinning) black hole binaries (BBHs), showing the performance of a recently completed, NR-informed, EOB model (arXiv:1506.08457) able to generate highly faithful waveform from the quasi-circular inspiral, through plunge, merger and ringdown; (ii) coalescence of neutron star (NS) binaries, with particular emphasis on the modelization of tidal effects up to merger, whose measurability in gravitational wave experiments will likely allow us to put strong constraints on the equation of state of ultra-dense matter; (iii) the strong-field scattering of BBHs as a useful numerical laboratory to extract strong-field information to complete the EOB analytical model. I will show several examples where state-of-the-art NR simulations can inform the EOB model so to build a comprehensive EOBNR model of the two-body dynamics and waveforms in general relativity.
Dr. Matteo Brogi CU Boulder, Colorado Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Alessandro Sozzetti Exoplanet Atmospheres at high spectral resolution 2016-04-05 14:00:00 Invited seminar Link You Tube abstract
After only two decades from the first discoveries, we know today about 2,000 planets orbiting stars other than the Sun. In order to truly understand the nature and the properties of these exoplanets, we need to study their atmospheres, a task performed nowadays with a range of observational techniques. In this talk I will focus on groundbased high resolution (R>20,000) spectroscopy, which has recently excelled in delivering robust molecular detections and estimating their relative abundances. I will review the major breakthroughs achieved in recent years, among which are the first atmospheric detections for nontransiting planets, and the unprecedented measurements of their true masses and orbital inclinations. I will then focus on the recent detection of the rotation and atmospheric winds of HD 189733b, a Jupitersize planet orbiting a K12V star in 2.2 days. We measure a combined absorption of CO and H2O lines with a confidence level of 7.6 sigma. The signal is obtained by cross correlating the data with theoretical spectra, and is maximized for a planet rotational velocity of 3.5(+1.1 -2.6) km/s. This corresponds to a planet rotational period of 1.7(+4.9 -0.4) days, consistent with the known planet orbital period of 2.2 days and therefore with tidal locking. Although we rule out at high confidence (3 sigma) planet rotation faster than 1.1 days, norotation is only marginally excluded (1.2sigma). Finally, we detect a small (1.7 km/s) daytonight side winds. Compared to previouslydetected sodium doppler shifted by 8 km/s, it likely implies a strong shear between the atmospheric pressures probed by these high dispersion observations (0.1-0.001 bar), and the outermost atmospheric layers where the core of the sodium lines is formed.
Dr. Roberto Soria Curtin Institute of Radio Astronomy, Perth, Australia Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Alessandro Capetti The most powerful jets from stellar-mass black holes 2016-03-17 11:00:00 Seminar Link You Tube abstract
Until a few years ago, it was assumed that black holes in X-ray binaries could not accrete mass at a rate exceeding the Eddington limit, because radiation pressure would stop gas inflows. However, there is now strong evidence that the most luminous X-ray binaries ("ultraluminous X-ray sources") in nearby galaxies are accreting well above that limit. Furthermore, there is also evidence that at least a fraction of those sources are also producing fast jets or massive outflows, with kinetic power comparable with the radiative luminosity. I will illustrate examples of such outflows, and discuss ways to measure the kinetic power, from their ionizing effects on the surrounding gas (ULX bubbles). Fin-a a quàich agn fà, as chërdìa che i përtus nèir a podèjsso nen esse pì luminos dël lìmit 'd Eddington, përchè la pression dovùa a la radiassion a dovrìa fermé ël gas prima ch'a dròcheissa a travers 'd l'orisont. Nopà, ancheuj a l'é ciàir che le binarie X pì luminose ("sorgiss X ultra-luminose") dëscurvì ant le galassie davzin-e a s'angrandisso motobin pì an pressa ëd cost lìmit. As peul ëdcò determiné da l'osservassion ant la banda radio e òtica che almen quaidun-e 'd cole sorgiss a produvo n'emission ëd jets relativìstich o vent massiv, con una potensa cinética sìmil a soa radiassion luminosa. I mostrërai quàich esempi ëd coi jets, e i discutrai dij métod për misuré la potensa cinética an partend daj sò efet ëd jonisassion ant ël gas dantorn (gòle dij ULX).
Prof. Raffaella Morganti Astronomy Group at ASTRON, Kapteyn Institute in Groningen Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Alessandro Capetti Cold gas outflows and life-cycle of radio galaxies 2016-03-14 11:00:00 Invited seminar Link You Tube abstract
Radio galaxies are episodic in nature, cycling through periods of activity and quiescence. Studying their life-cycle and the role that the cold gas has throughout the different phases of their life is key for understanding the impact these AGN have on their host galaxy. In this talk I will present recent results that cover two broad topics. I will present our studies on the presence and characteristics of fast outflows of cold gas (atomic and molecular) in radio galaxies. In particular, I will focus on the effect that the radio jets may have on this gas and how this can be described by numerical models. I will discuss the important connection between the evolutionary stage of the radio source and the effect of the radio plasma on the surrounding ISM. In the second part of the talk, I will present results from our search of dying and restarted sources aimed at understanding the duty-cycle of radio sources. This search is done in the MHz-domain using the LOFAR radio telescope and the continuum surveys that are now in progress. The results will be compared with evolutionary models of radio sources developed by our group and I will present some preliminary results from this effort.
Dr. Francois Colas IMCCE - Observatoire de Paris Osservatorio Astrofisico di Torino, Sala Seminari Villa Magliola Alberto Cellino French Fireball Network FRIPON : the link between asteroids and meteorites 2016-03-01 11:00:00 Seminar Link You Tube abstract
FRIPON (Fireball Recovery and InterPlanetary Observation Network) was recently founded by ANR (Agence Nationale de la Recherche). Its aim is to connect meteoritical science with asteroidal and cometary science in order to better understand our solar system formation and evolution. The main idea is to set up an observation network covering all the French territory to collect a large number of meteorites (one or two per year) with accurate orbits, allowing us to pinpoint possible parent bodies. 100 all-sky cameras are currently in installation forming a dense network with an average distance of 100km between stations. To maximize the accuracy of orbit determination, we will mix our optical data with radar data from the GRAVES beacon received by 25 stations. As both the setting up of the network and the creation of search teams for meteorites will need manpower beyond our small team of professionals, we are developing a citizen science network called Vigie-Ciel. The public at large will thus be able to simply use our data, participate in search campaigns or even setup their own cameras. As the efficiency of the network is proportioanl to its surface we hope to extend the network over Italy, starting with a first installation in Torino.
Ugo Locatelli (intro di Mariateresa Crosta) INAF-Osservatorio Astrofisico di Torino Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Mariateresa Crosta Mattang lucente. La rete celeste di Gaia 2016-02-18 11:00:00 Seminar Link You Tube abstract
Nella recente edizione di "Luci d'artista 2015/2016 - Torino" l'installazione Mattang lucente. La rete celeste di Gaia è stata presentata da novembre a gennaio in piazza Castello. L'opera è stata ideata dall'artista sperimentale Ugo Locatelli, con il contributo della ricercatrice Mariateresa Crosta per la curatela scientifica e del lighting designer Davide Groppi (vincitore del premio Compasso d'Oro dell'ADI nel 2014). E' la ricostruzione luminosa di un antico "Mattang" polinesiano, una mappa dei sistemi di onde, correnti marine e venti, fabbricato dagli isolani per muoversi nell'arcipelago. Oggetto di studio nell'Etnomatematica (Ascher Marcia, Etnomatematica. Esplorare concetti in culture diverse, Boringhieri 2007) e attualmente tema di un dottorato di ricerca presso la Facoltà di Design di Genova (Filippo Lezoli, già autore di una tesi di laurea sul percorso di ricerca giovanile di Ugo Locatelli). L'installazione è una metafora della navigazione esplorativa aperta e richiama il concetto della mappatura relativistica in corso nella nostra Galassia attraverso la luce stellare: la rivoluzionaria missione europea Gaia, lanciata dall'Agenzia Spaziale Europea nel 2013, di cui Torino detiene la leadership scientifica per la partecipazione italiana.
Dr. Massimiliano Belluso INAF - Osservatorio Astrofisico di Catania Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Daniele Gardiol Introduction to FPGA for astrophysical applications 2016-02-11 11:00:00 Invited seminar Link You Tube abstract
Dr. Alessandro Lanzafame di Fisica e Astronomia, Univ. di Catania e INAF- Osserv. Astrofisico di C Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Mario Lattanzi Rotational evolution of slow-rotators sequence stars 2016-01-28 11:00:00 Seminar Link You Tube abstract
The observed mass-age-rotation relationship in open clusters shows the progressive development of a slow-rotators sequence in a mass interval corresponding to stars having a radiative core and a convective envelope in their main-sequence evolution. After 0.6 Gyr, most cluster members have settled on this sequence. The observed clustering on this sequence suggests that it corresponds to some equilibrium or asymptotic condition that still lacks a complete theoretical interpretation, crucial to our understanding of the stellar angular momentum evolution. Here we couple a rotational evolution model that takes into account internal differential rotation with classical and new proposals for the wind braking law, and fit models to the data using a Monte Carlo Markov Chain (MCMC) method tailored to the case at hand. We explore the extent to which these models are able to reproduce the mass and time dependence of the stellar rotational evolution on the slow-rotators sequence. The description of the early evolution of the slow-rotators sequence requires taking into account the transfer of angular momentum from the radiative core to the convective envelope and we find that, in the mass range (0.85, 1.10) Msun, the core-envelope coupling time-scale for stars in the slow-rotators sequence scales as M^{-7.28}. Quasi-solid body rotation is achieved only after 1 - 2 Gyr, depending on stellar mass, which implies that verifying small deviation from the Skumanich law would require period data of older open clusters than available to date. Small deviations from the proportionality of the wind braking law to the cube of the angular velocity are in fact found compatible with the observations in the (0.1-2.5 Gyr) age range, their main consequence being a different prediction for the core angular momentum storage. The observed evolution in the (0.1-2.5 Gyr) age range and in the (0.85, 1.10) Msun mass range is best reproduced by assuming an empirical mass dependence of the wind angular momentum loss proportional to the convective turnover time-scale and the stellar moment of inertia. Rotational evolution tracks based on our MCMC fit provide a tool for inferring stellar ages of solar-like main-sequence stars from their mass and rotational period, which represent an alternative gyro-chronology relationship that takes into account the physics of the two-zone model for the stellar angular momentum evolution.
Dott. Enrica Lamia Istituto d'Arte Applicata e Design - IAAD Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Alberto Cora Inaf Education/Edu Inaf: identità visiva e prospettive 2015-11-05 11:00:00 Seminar Link You Tube abstract
Che cos’è un’identità visiva? Come si costruisce e consolida nel tempo? Il seminario affronterà l’importanza della comunicazione e del visual design nelle sue applicazioni più classiche: una strategia di comunicazione efficace, l’utilizzo del logo e il panorama dei siti web oggi. L’incontro sarà tenuto da Enrica Lamia, laureata in Comunicazione e Graphic Design presso lo IAAD di Torino, che presenterà una proposta di identità visiva per Inaf Education, oggetto del suo progetto di tesi.
Dr. Marco Pignatari Konkoly Observatory, Hungarian Academy of Sciences, Budapest, Hungary Osservatorio Astrofisico di Torino, Sala Seminari Villa Magliola Claudia Travaglio The "new" intermediate neutron capture process: old carbon-rich stars, presolar stellar dust and open clusters. 2015-10-29 11:00:00 Invited seminar Link You Tube abstract
The existence of the intermediate neutron capture process (i process) in stars was proposed in 1977 [1]. However, the first direct observation of the i process was only in 2011, in the post-AGB star Sakurai's object [2]. Since then, we are collecting a growing number of possible observations of the i process abundance signature, in old metal-poor C-rich stars, in young open clusters and even in presolar stellar dust found in carbonaceous meteorites today. This means that the i process might have played a relevant role also for galactic chemical evolution. These discoveries may help to solve several puzzles still affecting our knowledge on stellar nucleosynthesis, but on the other hand is challenging the capabilities of baseline stellar models. The i process is a product of ingestion of H in hot He-burning layers, and one-dimensional hydrostatic models are simply not capable to properly solve these events. In my talk I will discuss about the news and the open problems of this "old" neutron capture process. [1] Cowan, J.J., & Rose, W.K. 1977, ApJ, 212, 149; [2] Herwig, F., Pignatari, M., Woodward, P.R., et al. 2011, ApJ, 727, 89.
Dr. Fabrizio Capaccioni INAF IASF Sezione di Roma, Via Fosso del Cavaliere 100, Tor Vergata, Roma Osservatorio Astrofisico di Torino, Sala Seminari Villa Magliola Alberto Cellino La missione Rosetta e la cometa 67P/Churyumov-Gerasimenko: I risultati scientifici di una missione epocale. 2015-10-22 11:00:00 Invited seminar Link You Tube abstract
ROSETTA è la missione Cornerstone del programma ESA Horizon 2000 dedicata all’esplorazione dei corpi minori del Sistema Solare ed è la prima sonda ad “orbitare” una cometa, nonché la prima a rilasciare un “lander” (Philae) per l’analisi in-situ del nucleo cometario. Rappresenta senza dubbio la missione più ambiziosa e complessa mai tentata dall’Agenzia Spaziale Europea. Rosetta è stata lanciata il 2 marzo 2004 e, nel 2008 e 2010, ha effettuato due fly-bys con gli asteroidi 2867 Steins e 21 Lutetia nel corso della sua marcia di avvicinamento all’obiettivo primario della missione: la cometa 67P/Churyumov-Gerasimenko. Il 6 Agosto la sonda Rosetta è arrivata alla distanza di 100km dal nucleo ed ha iniziato la sua attività di mappatura della superficie per identificare la zona più adatta all’atterraggio del lander Philae, che ha effettivamente raggiunto la superficie lo scorso Novembre. La missione del lander è stata di breve durata, ma la sonda Rosetta da allora ha iniziato la sua attività di “scorta” della cometa che accompagnerà nel corso del suo passaggio all’interno del Sistema Solare fino a circa la metà del 2016. Il perielio è stato raggiunto il 13 Agosto ad una distanza di 1.24AU dal Sole. La missione ROSETTA ospita a bordo 10 strumenti (più il lander Philae che ne ospita altri 10) con una forte rappresentanza italiana: VIRTIS (PI F. Capaccioni – IANF) lo spettrometro che studia la composizione della cometa, GIADA (PI A. Rotundi, Università Parthenope) un analizzatore di grani di polvere della cometa, OSIRIS (Co-PI C. Barbieri Università di Padova) la camera per l’osservazione della cometa; è inoltre italiano il trapano SD2, a bordo di Philae, necessario per la raccolta in profondità dei campioni di ghiacci cometari. La presentazione descriverà la missione Rosetta ed i risultati scientifici più rilevanti finora ottenuti.
Dr. Paolo Tozzi INAF - Osservatorio Astrofisico di Arcetri, Firenze Osservatorio Astrofisico di Torino, Sala Seminari Villa Magliola Alessandro Capetti X-ray properties of medium and high-z clusters 2015-10-09 11:00:00 Invited seminar Link You Tube abstract
Distant clusters of galaxies are today a well known case for X-ray astronomy. Several clusters have been identified in the last few years up to z~2, thanks to serendipitous X-ray deep observations, IR or SZ surveys, or a combination of these techniques. These findings potentially may have a very strong impact on many fields like cosmology, large scale structure of the Universe, evolution of the cluster galaxy population, and interactions between the IntraCluster Medium and the member AGNs. However, these studies are limited due to the very time-consuming follow-up needed to investigate high-z clusters. Here we report deep X-ray follow-up of some medium and high z clusters (in particular the Phoenix at z~0.6, WARP1415 at z~1, CXO1415 at z~1.5 and XDCP0044 at z=1.58) obtained with the Chandra and XMM satellites, to reach new insights on specific issues like the evolution of the cool core phenomenon, the chemical evolution of the ICM, and the growth of large scale structure of the Universe. These studies are also discussed in the perspective of a systematic, complete investigation of the high-z cluster population.
Dr. Marco Chiaberge IRA & STSCI Osservatorio Astrofisico di Torino, Sala Seminari Villa Magliola Alessandro Capetti The origin of radio-loud AGN 2015-07-06 11:00:00 Seminar Link You Tube abstract
Radio-loud AGNs are invariably associated with the most massive galaxies and the most massive black holes. The origin of their relativistic jets is still an open issue. While we still don’t know the details of the physics of jet launching, we recently achieved important information from observations of a large number of these objects. In this talk, I will focus on results from our HST studies of radio galaxies from z~0 to z~2.5. In an attempt to investigate the role of mergers in triggering these AGNs, we measured the merger fraction of Type 2 radio-loud and radio-quiet active galactic nuclei at z>1 using new samples. The full sample spans an unprecedented range in both redshift and AGN luminosity. We performed statistical tests to determine whether the different samples are differently associated with mergers. We find that (almost) all radio-loud galaxies at z>1 are clearly associated with recent or ongoing merger events. This is independent of the AGN power. The same properties are seen at lower redshifts. Conversely, the merger fraction for samples of radio-quiet objects at z>1 is indistinguishable from that of non-active galaxies in the same redshift range. This is strong evidence that mergers are the ultimate triggering mechanism for the radio-loud AGN phenomenon. I will discuss a possible scenario that may account for the origin of jets in the framework of our new results.
Dr. Luigi Guzzo INAF - Osservatorio Astronomico di Brera Osservatorio Astrofisico di Torino, Sala Seminari Villa Magliola Ummi Abbas Cosmology with Galaxy Redshift Survey 2015-06-24 11:00:00 Seminar Link You Tube abstract
Galaxy redshift surveys are one of the experimental pillars on which the standard model of cosmology rests. Even larger projects are ongoing or planned, with the goal of understanding the nature of cosmic acceleration and the origin of galaxies. In my talk I will review this situation and show how redshift surveys allow us to possibly break the degeneracy between dark energy and modified gravity by measuring both the expansion rate and the growth rate of structures. At the same time I will discuss how precision cosmology implies a careful understanding of the survey selection function, to assure systematic errors are kept under strict control. This requires a deep comprehension of how the specific galaxies in our sample trace the underlying mass distribution, thus defining different survey strategies with specific advantages and disadvantages. As a specific example, I will introduce the recently completed VIPERS survey at the ESO Very Large Telescope. VIPERS is the largest redshift survey ever conducted with ESO telescopes and has collected a complete sample of 90,000 galaxies with measured redshifts at 0.5<z<1.2. It fills a unique niche in terms of volume and sampling density at these redshifts, being the only survey at z~1 that is comparable in this respect to the classical SDSS and 2dFGRS at z~0. For the first time we are able to see the details of filaments, superclusters and voids and measure their statistical properties, at an epoch when the Universe was about half its current age.
Dr. Vania Da Deppo IFN-CNR Padova Osservatorio Astrofisico di Torino, Sala Seminari Villa Magliola Daniele Gardiol La Wide Angle Camera per la missione spaziale Rosetta: realizzazione on-ground e immagini in-flight 2015-06-11 11:00:00 Invited seminar Link You Tube abstract
Dal 8 agosto 2014 la sonda europea Rosetta si trova in orbita attorno alla cometa 67P/Churyumov-Gerasimenko. La Wide Angle Camera del sistema di imaging OSIRIS è una camera a grande campo di vista specificamente progettata per osservare i gas e i getti di polvere che escono dalla superficie della cometa. La WAC è stata progettata, allineata e calibrata presso il laboratorio LUXOR del CNR-IFN di Padova, in collaborazione con l'Università di Padova. Il seminario si propone di raccontare le fasi saliente della realizzazione della camera e illustrare le immagini acquisiste occasionalmente durante il lungo periodo che la sonda ha trascorso in orbita nel sistema solare. Per concludere con le immagini spettacolari della superficie e dei getti che la sonda sta raccogliendo giorno per giorno seguendo la cometa nella sua fase di avvicinamento al sole.
Prof. Guido Cossard Istituzione Scolastica Saint-Roch di Aosta Osservatorio Astrofisico di Torino, Sala Seminari Villa Magliola Alberto Cora Riti astronomici di fondazione delle città romane ed etrusche 2015-06-04 11:00:00 Invited seminar Link You Tube abstract
Il seminario vuole discutere gli aspetti astronomici legati alla fondazione delle città antiche, in particolare di quelle romane. Si intendono inoltre introdurre i metodi archeoastronomici per effettuare i rilievi dei reperti archeologici legati alle fondazioni e i procedimenti per accertarne l'eventuale orientamento astronomico.
Drs. Daniele Gardiol & Antonio Stamerra INAF-Osservatorio Astrofisico di Torino Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Alessandro Bemporad Cherenkov Telescope Array @ OATo 2015-05-27 11:00:00 Seminar Link You Tube abstract
After a short review of the CTA project (Stamerra) we will provide an overview of the technological activities ongoing here in Torino to support the italian participation to the consortium (Gardiol).
Dr. Giuseppe Murante INAF - Osservatorio Astronomico di Trieste Osservatorio Astrofisico di Torino, Sala Seminari Villa Magliola Anna Curir Simulating disk galaxies with a novel sub-grid prescription 2015-05-13 11:00:00 Seminar Link You Tube abstract
I will introduce the problem of numerical galaxy formation in a cosmological context, giving a short review of the current state of the art. I will then results of cosmological simulations of disk galaxies where star formation and stellar feedback are described using our MUlti Phase Particle Integrator (MUPPI) model. This description is based on a simple multi-phase model of the interstellar medium at unresolved scales, where mass and energy flows among the components are explicitly followed by solving a system of ordinary differential equations. Thermal energy from SNe is injected into the local hot phase, so as to avoid that it is promptly radiated away. A kinetic feedback prescription generates the massive outflows needed to avoid the over-production of stars. We obtain spiral galaxies with small bulge-over-total stellar mass ratios, extended stellar and gas disks, flat rotation curves and realistic values of stellar masses. Star formation rates follow the observed Schmidt-Kennicutt relation. Stars kinematically belonging to the bulge form early, while disk stars show a clear inside-out formation pattern and mostly form after redshift z=2. Results are found to be remarkably stable against resolution. I will then shorty describe the application of our prescription to cosmological volumes, and the future developments of our scheme.
Dr. Paolo Pagano School of Mathematics and Statistics, University of St. Andrews, UK Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Alessandro Bemporad Study on the polarization ratio technique for 3d reconstruction of CMEs with METIS 2015-04-29 11:00:00 Seminar Link You Tube abstract
CMEs are the main driver of Space Weather and very violent events which have been not completely understood. One challenge lies on the difficulty of studying their 3D structure because of the projection effect. By means of the polarization ratio technique we infer the position of the plasma along the line of sight. METIS, the coronagraph on board Solar Orbiter, will observe CMEs in polarized light and will study the 3D structure of CMEs. Our aim is to evaluate the errors associated with the technique. First we apply the technique to an analytic distribution of plasma and second to the distribution of plasma resulting from a 3D MHD simulation of a flux rope ejection. Using the 3D plasma distribution in the MHD simulation, we synthesize the polarized and total brightness observations of METIS. We apply the polarization technique to the synthesized observations to estimate the accuracy and the errors of the technique. We provide an interpretation of the results of the technique as the centre of mass of the plasma distribution along the line of sight, we evaluate the error in the position of the centre of mass and direction of propagation of the CME and finally we evaluate the error in the column density measurements obtained from the polarization ratio technique. In conclusion, our study provides a framework to explore the potential of the METIS Coronagraph and to interpret the future polarized light observations of CME in a Space Weather context.
Dr. Roberto Peron Istituto di Astrofisica e Planetologia Spaziali (IAPS-INAF) Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Alberto Vecchiato La relatività generale nel sistema solare: fenomenologia e verifiche sperimentali 2015-04-23 11:00:00 Invited seminar Link You Tube abstract
La relatività generale ha un secolo di vita. Dal tempo della sua formulazione, la teoria di Einstein è apparsa come la migliore descrizione a nostra disposizione dei fenomeni gravitazionali; e questo su di un enorme intervallo di scale, da quelle umane (di laboratorio) a quelle cosmologiche, con spettacolari predizioni come l'espansione dell'universo e le onde gravitazionali. Decine di anni di verifiche sperimentali non hanno mostrato deviazioni significative fra teoria ed esperimento. Eppure questa teoria continua a essere messa in discussione da diverse direzioni. Risultati teorici indicano correzioni quasi necessarie, al fine di conciliare la teoria stessa con i principi quantistici (e risolvere apparenti paradossi). Le componenti "oscure" che appaiono in sede astrofisica e cosmologica sono una recente e difficile sfida; esse trovano possibili spiegazioni in altri campi "gravitazionali" fondamentali, che si dovrebbero aggiungere al campo metrico della relatività generale. Tuttavia, guardando con un certo dettaglio all'evidenza fenomenologica in supporto all'attuale conoscenza dell'interazione gravitazionale, troviamo scarsa evidenza di precisione, dalla scala del sistema solare fino all'intero universo, con una corrispondente proliferazione di teorie "alternative". In ogni caso, il sistema solare rimane un'arena privilegiata per le verifiche di precisione della gravitazione, non da ultimo per la possibilità di avere un certo controllo su almeno alcune delle quantità fisiche in gioco. Per motivi di ordine pratico, queste verifiche sono spesso collegate alla stessa esplorazione del sistema solare, e più in generale alla scienza spaziale. In questo seminario la fenomenologia gravitazionale nel sistema solare verrà discussa, assieme ad una selezione di verifiche sperimentali, passate e presenti (in particolare verifiche del Principio di Equivalenza, inseguimento laser - Satellite Laser Ranging e Lunar Laser Ranging - e radiometrico di satelliti e sonde, sia in orbita terrestre che nello spazio profondo). Una certa enfasi verrà data alle complesse problematiche di modellizzazione implicite in molti di questi esperimenti, oltre che alle inerenti sfide tecnologiche.
Dr. Hoda Abedi Institut de Ciències del Cosmos, Universitat de Barcelona, IEEC, Spain Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Ronald Drimmel On the characterisation of the Galactic warp in the Gaia era 2015-04-16 11:00:00 Seminar Link You Tube abstract
We explore the possibility of detecting and characterising the warp of the stellar disc of our Galaxy using synthetic Gaia data and two available proper motion catalogues, namely UCAC4 and PPMXL. We develop a new kinematic model for the galactic warp. We generate random realisations of test particles which evolve in a realistic Galactic potential warped adiabatically to various final configurations. In some cases a twist is introduced additionally. The Gaia selection function, its errors model and a realistic 3D extinction map are applied to mimic three tracer populations: OB, A and Red Clump stars. A family of Great Circle Cell Counts (GC3) methods is used. They are ideally suited to find the tilt and twist of a collection of rings, which allow us to detect and measure the warp parameters. We show how the use of kinematics improves the accuracy in the recovery of the warp parameters. The OB stars are demonstrated to be the best tracers determining the tilt angle with accuracy better than 0.5 degrees up to galactocentric distance of 16 kpc. Moreover, We introduce LonKin methods that help us detect the kinematic signature of the warp in the vertical motions of stars as a function of galactic longitude. Applying this method to the UCAC4 proper motions, we do not obtain a similar trend as the one we expect from our warp model. We explore a possible source of this discrepancy in terms of systematics caused by a residual spin of the reference frame with respect to the extra-galactic inertial one. We also look into a deeper proper motion survey, namely the PPMXL. An analytical fit to the vertical velocity trend of red clump stars suggests a vertical oscillation in the southern warp with a rather high frequency that tends to decrease the amplitude of the warp. We analysed this trend in the context of our warp model and an abrupt decrease of the warp's amplitude in a very short time of about one hundred Myr could explain this trend.
Dr. Sarah Gibson High Altitude Observatory, Boulder CO, US Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Silvano Fineschi FORWARD: A toolset for analyzing coronal magnetic fields 2015-03-19 11:00:00 Invited seminar Link You Tube abstract
Magnetism defines the complex and dynamic solar corona. Twists and tangles in coronal magnetic fields build up energy and ultimately erupt, hurling plasma into interplanetary space. These coronal mass ejections (CMEs) are transient riders on the ever-outflowing solar wind, which itself possesses a three-dimensional morphology shaped by the global coronal magnetic field. Coronal magnetism is thus at the heart of any understanding of space weather at the Earth. I will describe the current state of the art in coronal magnetometry, and present results from the Coronal Multichannel Polarimeter (CoMP) at Mauna Loa Solar Observatory (MLSO), which since 2011 has taken polarimetric observations of the solar corona in the near-infrared on a near-daily basis. I will discuss work in progress that utilizes forward modeling to synthesize polarimetric data at multiple heights and vantage points, and at wavelengths from radio to infrared to visible to ultraviolet. The goal is to use such synthetic testbeds to determine the ideal set of observations for constraining the coronal magnetic field, and to establish a Data-Optimized Coronal Field Model (DOC-FM) that efficiently incorporates these data into global magnetic models. This work will provide essential tools and motivation for the planning and implementation of future coronal polarimetric projects and missions spanning a broad range of wavelengths.
Dott. Fabio Bacchini Università di Torino - Dipartimento di Fisica Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Alessandro Bemporad Lagrangian MHD Particle-in-Cell simulations of coronal interplanetary shocks driven by observations 2015-02-05 11:00:00 Seminar Link You Tube abstract
We present the results of an analysis carried on the June 11th, 1999 CME event, using observational data from SOHO/LASCO and UVCS as a reference to compare simulation results obtained with the FLIPMHD3D code by Brackbill. The aim of the analysis is to compare the values of the plasma parameters along the CME-driven shock front, as retrieved from observations, with the values obtained by simulating an equivalent phenomenon with a fully implicit, visco-resistive Particle-in-Cell MHD code. The parameters of interest are the compression ratio, the magnetic field rotation and the Alfvénic Mach number; at the same time, this is useful to validate the semi-empiric formulation (taken from Bemporad et al. 2011) for the spatial distribution of the Alfvénic Mach number as a function of the compression ratio. Having analyzed the phenomenon with a one-fluid simulation, a simple one-dimensional two-fluid model is tentatively applied to retrieve the post-shock parameters for electrons and ions separately. This is done with a new Lagrangian Particle-in-Cell code, whose further development will hopefully lead to the creation of a powerful computational tool able to handle such problems in multi-dimensional simulations.
Dr. Mario Flock Astrophysics Division CEA France Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Gianluigi Bodo Magneto-Thermodynamics in Young Protoplanetary Disks 2015-01-28 15:00:00 Seminar Link You Tube abstract
The recent observation of HL Tauri (see ESO press release 1436a) by the Atacama Large Millimeter Array (ALMA) revealed, for the first time, the detailed substructures of gaps and rings within the disc that have never been seen before. Such upcoming observations will open a new area in the planet and star formation research. Only by the combined effort of the theoretical models and observations we will be able to study the evolution of the solid and gaseous material. In my talk I will present recent results from our study of the gas and dust dynamics and thermodynamics in magnetized and turbulent protoplanetary disks. I will demonstrate global 3D radiation non-ideal magneto-hydrodynamic stratified disk simulations, performed for Tauri disk system AS 209. The results will focus on the heating and cooling mechanism in fully turbulent and irradiated disks which are important especially for the inner disk regions. The results demonstrate that global radiation MHD simulations of turbulent protoplanetary disks are feasible with current computational facilities. This opens up the window to a wide range of studies of the dynamics of protoplanetary disks, especially their inner parts for which there are significant observational constraints.
Dr. Luisa Schiavone INAF-Osservatorio Astrofisico di Torino Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Alessandro Bemporad Oltre l'astronomia, la vita : Giulio Bemporad e l'assistenza ai profughi ebrei 2015-01-20 11:00:00 Seminar Link You Tube abstract
Il 14 dicembre 1938, in applicazione al R. Decreto Legge n. 1779 contenente le “norme per la difesa della razza nella Scuola italiana”, il personale di “razza ebraica” di tutte le istituzioni scolastiche di ogni ordine e grado fu dispensato dal servizio e dovette abbandonare il proprio posto di lavoro. Fra queste persone c’era anche Giulio Bemporad, astronomo presso l’Osservatorio astronomico di Torino, dove lavorava e viveva. In occasione del settantesimo anniversario dell’apertura dei cancelli di Auschwitz, l’Università di Bologna e il Servizio Biblioteche e Archivi storici dell’INAF organizzeranno una giornata di studio in ricordo degli astronomi ebrei che furono espulsi in applicazione delle leggi razziali. In anticipo sulla conferenza che si terrà a Bologna il 26 gennaio 2015, vengono qui presentati i risultati di un’approfondita ricerca storico-archivistica sulla figura di Giulio Bemporad da cui sono emersi particolari finora sconosciuti, tra cui il fondamentale ruolo che ebbe a Torino prima nel Comasebit e poi nella Delasem, le due organizzazioni di soccorso ai profughi ebrei che operarono in Italia a partire dai primi provvedimenti antiebraici.
Prof. Leon Ofman Catholic University of America and NASA/Goddard Space Flight Center, Code 671, G Osservatorio Astrofisico di Torino, Sala Seminari Villa Magliola Lucia Abbo Observations and Models of the Slow Solar Wind Sources 2015-01-14 11:00:00 Invited seminar Link You Tube abstract
The slow solar wind is highly variable and dense compared to the fast wind streams, and is associated with coronal streamers. It is the dominant form of the solar wind during periods of solar maximum activity. The slow solar wind was observed in-situ from 0.29AU, and was studies using white light and spectroscopic observations. Observations show that heavy ion properties and morphology of streamers are often different than protons. While the corona and the solar wind were modeled with single-fluid MHD in the past, multi-fluid modeling is required to account for the properties of heavy ions, and study the sources of the slow wind. I will present the results of 2.5D and 3D multi-fluid models that include heavy ions such as O5+, Mg9+, and He++, and show results of synthetic observations that use the results of the multi-fluid models facilitating the interpretation of spectroscopic data. I will discuss the impact of the modeling on our understanding of the slow solar wind and its sources in coronal streamers.
Prof. Giampiero Naletto University of Padova Via Gradenigo, 6/B I-35131 Padova Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Alessandro Bemporad La missione Rosetta e il rendez-vouz con la cometa 67P/Churyumov-Gerasimenko 2014-12-12 11:00:00 Invited seminar Link You Tube abstract
Rosetta è la missione cornerstone dell'ESA per raggiungere la cometa 67P/Churyumov-Gerasimenko, orbitarle attorno e infine atterrarci sopra. Rosetta sta esaminando la cometa con una serie di strumenti remoti e di misure in situ; inoltre, il lander Philae analizzerà la superficie cometaria con una serie di strumenti di imaging e di campionamento del terreno. Rosetta è stata lanciata nel 2004, ha effettuato quattro gravity-assists, ha effettuato due flybys con gli asteroidi 2867 Steins (nel 2008) e 21 Lutetia (2010), ed è entrata in ibernazione nel 2011. Dal suo "risveglio" il 20 Gennaio 2014, ha iniziato l'osservazione ravvicinata della cometa; in Agosto è stato effettuato il rendez-vous con la cometa e l'atterraggio del lander è attualmente previsto il giorno 11 Novembre 2014. Rosetta seguirà la cometa fino a dopo il suo passaggio al perielio fino alla fine del 2015. Si presenteranno le principali caratteristiche della missione e i principali risultati scientifici finora ottenuti.
Dr. Luigi Mancini Max Planck Institute for Astronomy, Heidelberg, Germania Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Alessandro Sozzetti Accurate characterisation of transiting exoplanets by photometric follow-up observations 2014-11-26 11:00:00 Invited seminar Link You Tube abstract
Among the almost 2000 extrasolar planets already confirmed, those that transits in front of their parent stars are of great interest. In fact, most of the physical and orbital parameters of transiting extrasolar planet systems are easily to achieve, with accuracies of few percents, through standard astronomical observations. Estimations of the planets' mass and size allow us to discriminate between gaseous and rocky planets and infer their formation and evolution history. A deduction of their chemical composition is also possible by looking for element and molecule imprint in the transmission spectra measurable during transit events. However, many of the discovered transiting planets do not have high-quality light curves, so their physical properties are poorly known. In this perspective, we are leading a large program with an array of medium-class telescopes to obtain ultra-high-precision photometry of transit events, which are analysed to accurately measure the physical properties of know planetary systems. Besides measuring and refining the physical properties of the planets and their parent stars, we also try to obtain additional information from the light curves, by identifying particular features of the systems (e.g. stellar activity) and investigating the composition of the planetary atmospheres by transmission photometry. In this lecture, I will present several observational strategies that we adopt to achieve these goals.
Prof. Lucio Russo Università degli Studi di Roma Tor Vergata, Via della Ricerca Scientifica Osservatorio Astrofisico di Torino, Sala Seminari Villa Magliola Alberto Vecchiato Il biennio 146-145 a.C.: uno spartiacque nella storia della cultura? 2014-11-12 11:00:00 Invited seminar Link You Tube abstract
Con l'età Ellenistica l'incontro delle società greca e orientale diede origine ad una rivoluzione culturale che portò per la prima volta alla nascita di una cultura "moderna" e del metodo scientifico. Questo fenomeno durò per due secoli e fece sviluppare diverse discipline scientifiche ad un livello che non sarebbe più stato raggiunto fino a tempi recenti. Si esporrà quindi la tesi che gli eventi del 146-145 a.C., che assicurarono a Roma il dominio su tutto il Mediterraneo, provocarono una brusca interruzione della produzione intellettuale, e in particolare scientifica. Il conseguente tracollo culturale, in genere ignorato o sottovalutato, è illustrato con esempi tratti da varie scienze, con particolare rilievo nei confronti dell'Astronomia e della Fisica.
Irene Agulli Instituto de Astrofisica de Canarias, C/ Vía Láctea, s/n E38205 - Osservatorio Astrofisico di Torino, Sala Seminari Villa Magliola Alessandro Bemporad The origin of dwarf galaxies in clusters: the faint end slope of the galaxy luminosity function 2014-10-29 11:00:00 Seminar Link You Tube abstract
Dwarf galaxies (M_b < -18) are the most abundant objects in the Universe. Red dwarf galaxies are preferentially located in high density environments point out a non primordial origin of this kind of systems. The galaxy luminosity function (LF) is a powerful tool to study the formation and evolution of galaxies in different density environments. We measured the spectroscopic LF of the nearby and massive Abell 85 (A85) cluster down to M* + 6. This LF was fitted by a double Schechter function and shows an upturn at faint magnitudes (Mr>-18.0). This upturn is not observed in other spectroscopic LFs of nearby galaxy clusters, but it presents a slope similar to the one measured for the field population. Nevertheless, the faint end population of A85 is formed by red galaxies, unlike the field one. We conclude that the cluster environment does not play a major role in the formation of the slope of the LF. However, the environment influences the nature of the faint-end galaxies by transforming faint galaxies from blue to red ones. This can be explained by the transformations involving the loss of gas of the galaxies and a subsequent quench of its star formation.
Paolo Tanga Observatoire de la Côte d’Azur, Nice, France Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Alberto Cellino Physical properties of asteroids: preparing the Gaia era 2014-10-21 11:00:00 Invited seminar Link You Tube abstract
Nell'epoca delle missioni spaziali che visitano asteroidi e comete, il ruolo delle osservazioni a distanza e delle surveys sistematiche non viene meno. Se le missioni in situ ci forniscono indicazioni dettagli di grande importanza sulle superfici (craterizzazione, distribuzione della regolite, composizione chimica...) molte questioni chiave restano senza una risposta, in particolare circa la struttura interna, per la quale scarseggiano anche gli indizi indiretti. In particolare, conosciamo molto poco e male la densità media della maggior parte dei corpi minori, e non sappiamo nulla circa la compattezza, il grado di frammentazione o di differenziazione. Le osservazioni a distanza, oggi, costituiscono ancora una componente estremamente importante per cercare di capire meglio questi aspetti. Gaia appartiene a questo contensto, e si presenta come una potenziale rivoluzione per lo studio del Sistema Solare. Faremo quindi il punto della situazione sulle osservazioni degli asteroidi, che sono evolute in misura notevole negli ultimi 20 anni e discuteremo, in un quadro piu' generale, dell'impatto che Gaia avrà sulle tecniche di osservazione da Terra in quest'ambito.
Rene A. Mendez B. Departamento de Astronomia & Observatorio Astronomico Nacional Universidad d Sala Planetario Ricky Smart The Cramér-Rao theorem in photometry and astrometry 2014-10-16 11:00:00 Invited seminar Link You Tube abstract
Optimal parameter estimation can, in general, be formulated using “decision-making” theory (Cover & Thomas 2006). This framework can also provide absolute lower bounds to the uncertainty of these estimators. For example, the "Cramer-Rao (CR) lower uncertainty bound" determines the minimum theoretical variance achievable by any unbiased estimator (Stuart, Ord, & Arnold 2004). We analyze the CR bound of a linear-detector in a 2-dimensional (2d) estimation scenario: Astrometric location and total flux of the source. Our CR estimates agree very well with the empirically determined maximum precisions achieved in photometry and astrometry: Astrometric accuracy vs. flux, ground (HST) & space-based optical astrometry, photometric precision at extremely high S/N. Thus, the CR can be used as a benchmark to guide in detector design, testing of pipelines, science planning and design of observational strategies. We plan to extend these studies to incorporate more subtle observational/detector features such as non-uniform pixel response functions, non-symmetric PSFs, rapidly fluctuating backgrounds, moving targets, radiation damage and CTE effects, among others. I discuss some of the limitations of the classical CR formulation and possible solutions.
Ivan Minchev Leibniz - Institut für Astrophysik, Potsdam, Germany Sala Planetario Alessandro Spagna The dynamic of the Galactic disk, the role of the central bar and spiral arms 2014-09-18 11:19:00 Invited seminar Link You Tube abstract
Disc non-axisymmetric components, such as spirals and central bars, are nowadays known to play an important role in shaping galactic discs. Here we use Tree-SPH N-body simulations to examine the effect of these perturbers on two aspects: the occurrence of multiple patterns in discs and the effects of radial migration on disc thickening. We find that, in addition to a central bar, multiple spiral patterns and lopsided modes develop in all models. Interaction among these asymmetric features results in a large scale stellar migration. However, we show that, despite the strong radial mixing, discs cannot be thickened sufficiently to match observed thick discs. We relate this to the adiabatic cooling as stars migrate radially outwards. Our findings cast doubt on the plausibility of thick disc formation via stellar radial migration.
Prof. Vincenzo Carbone Universita' della Calabria Osservatorio Astrofisico di Torino, Sala Seminari Villa Magliola Daniele Telloni Leonardo da Vinci e la Turbolenza: dall' osservazione della realtà al desiderio di una risposta 2014-07-16 11:00:00 Invited seminar Link You Tube abstract
Verrà presentato il problema della turbolenza nei fluidi a partire dalle osservazioni di Leonardo da Vinci, che fu il primo a studiare il fenomeno ponendo una serie di questioni fondamentali, fino alle più recenti analisi statistiche relative al fenomeno dell'intermittenza e delle strutture multifrattali.
Prof. David Charbonneau Harvard-Smithsonian Center for Astrophysics (Cambridge, USA) Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alessandro Sozzetti The Fast Track to Finding an Inhabited Exoplanet 2014-06-23 11:00:00 Seminar Link You Tube abstract
The investigation of planets orbiting other stars has moved from the study of gas giants to the hunt for smaller planets that are predominantly rock and ice in composition. When such planets are discovered in edge-on orbits, such that the planet and star undergo mutual eclipses, we are granted the opportunity to determine directly the planetary masses and sizes. Most interestingly, we can study starlight filtered through the planetary atmosphere to deduce its chemical composition, and perhaps even search for biosignatures. I will summarize the most recent results from the NASA Kepler Mission and describe two surveys intended to find the closest habitable exoplanet. I will conclude by assessing the prospects for searching for atmospheric biosignatures on such worlds with an ELT.
Dott. Stefano Casertano Space Telescope Science Institute, Baltimora (US) Sala Planetario Mario Gilberto Lattanzi High precision parallax measurements with HST - towards a 1% determination of the Hubble Constant 2014-05-21 11:00:00 Invited seminar Link You Tube abstract
A new observing technique that has been implemented for the Wide Field Camera 3 on HST is capable of obtaining astrometric measurements with a precision of about 20 micro-arcseconds. Preliminary results from a project to measure trigonometric parallaxes of long-period Galactic Cepheids demonstrate the potential precision of this method, while underscoring the conditions needed to optimize the final accuracy of the parallax measurements. When complete in early 2015, our program will obtain distance measurements for 19 long-period Galactic Cepheids, with typical errors of a few percent per target at distances of 1 to 3 kpc. These Cepheids will form the best available calibrator for the local value of the Hubble Constant (expected error 1-2%) until the completion of the GAIA mission. Improved local measurements of the Hubble Constant are especially interesting in view of the recent claims of tension with the model estimates of H0 from the Planck mission.
Dott. Luigi Riba Dipartimento di Matematica Osservatorio Astronomico di Torino, Sala Seminari Villa Magliola Maria Teresa Crosta Stockwell transform and time-frequency analysis: theory and applications 2014-03-19 11:00:00 Seminar Link You Tube abstract
Extracting the time/frequency content of a signal is critical in many practical applications. Unfortunately, due to the Heisenberg uncertainty principle, it is impossible to simultaneously retain precise time and frequency information of a signal. Many techniques arose trying to deal with the uncertainty principle in order to obtain a �sufficiently good� time-frequency representation of a given signal. We here recall the short-time-Fourier transform and the wavelet transform. In 1996 the Stockwell transform (S-transform) has been introduced as a tool for analyzing geophysical data. Since then, it has been used in medical imaging, geophysics and signal processing in general. This transform is closely related to the short-time Fourier transform from which it differs due to its ability of adapting the width of the analyzing window according to the analyzed frequencies. More precisely, the Stockwell transform provides an increasingly good time/space localization of the analyzed frequency as the analyzed-frequency increases. For example, this property could be useful in localizing discontinuities in an image. Only recently, Y. Wang and J. Orchard developed a fast algorithm to compute the Stockwell coefficients. This algorithm has made this tool even more attractive for applications. In this talk, we introduce the one-dimensional Stockwell transform highlighting its connections with the short time-Fourier transform and the wavelet transform. Moreover, we will define a multi-dimensional Stockwell transform. In the end, we will show some applications in image processing such as filtering, watermarking and texture analysis.
Andrea Bianco INAF - Osservatorio Astronomico di Brera Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alberto Riva Volume Phase Holographic Gratings for astronomy: practical considerations 2013-12-04 11:00:00 Seminar Link You Tube abstract
Volume Phase Holographic Gratings (VPHGs) are becoming key dispersing elements in spectroscopic astronomical instrumentation thanks to unique features, such as high peak diffraction efficiency (up to 100%) that can be easily tuned in wavelength, large dispersion (up to 6000 l/mm), easy customization (each grating is a master grating), large size. The design of the grating in terms of dispersion and resolution is exactly the same of a classic ruled grating, whereas the design in term of diffraction efficiency requires a material optimization. Here, the possibilities provided by this technology will be shown focusing mainly on the recent results regarding the new devices mounted on AFOSC camera.
Oldřich Semerák Charles University in Prague, Fac. of Mathematics & Physics, Inst. of Theoretic Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Maria Crosta On chaos in deformed black-hole fields 2013-11-06 11:00:00 Seminar Link You Tube abstract
Black holes supposed to drive astrophysical sources are usually being modelled by the Kerr metric, but in reality they are neither isolated nor stationary, and they also do not seem to live in an asymptotically flat space-time. This queries the relevance of various black-hole theorems, but also, for example, spoils the complete integrability of geodesic equation. We have studied the geodesic dynamics in simple, static and axially symmetric exact space-times generated by an (originally) Schwarzschild black hole surrounded by an annular thin disc or ring, and observed how the motion of free test particles becomes chaotic for sufficiently large mass of the additional source and sufficiently large particle energy. A number of methods is available which can reveal how the geodesic dynamics depends on parameters; the latter can in particular be chosen so as to correspond to a specific astrophysical situation, e.g. the one in the Galactic nucleus.
Stefano Bertone Observatoire de Paris- Syrte Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alberto Vecchiato From Time Transfer functions to a model for relativistic astrometry in the Gaia era 2013-09-10 11:00:00 Seminar Link You Tube abstract
Modern space projects currently under development, such as BepiColombo for the exploration of Mercury or Gaia for space astrometry, have the goal of getting high precision data about their main targets. It is then necessary to conceive several independent models in the framework of General Relativity to perform data analysis ensuring the appropriate treatment of all effects important at the required level of accuracy. The first part of this presentation is dedicated to the study of light propagation. We use the Time Transfer Functions (TTF) formalism to characterize the influence of gravitational light deflection on the Ranging, Doppler and astrometric observables for applications to these future projects. In order to get an appropriate gravitational description of the Solar System, we consider the hypothesis of a weak gravitational field, adopting a metric tensor valid up to the second order of the post-Minkowskian (2PM) approximation. We obtain these observables as integrals depending on the metric tensor and its derivatives only. This very general form is particularly adapted to numerical computation and to the test of alternative theories of gravity. We also propose several analytical applications of our results up to the 2PM order. In the second part of this presentation, we focus on high precision astrometry in the context of the Gaia mission, scheduled for launch in late 2013. We use an original procedure to get an analytical comparison of our light propagation model with the two approaches developed for Gaia, namely the Gaia Relativity Model (GREM) and the Relativistic Astrometric Model (RAMOD). Following this validation, we use the TTF and the Gaia tetrad developed for RAMOD to simulate a series of astrometric observations within the Global Sphere Reconstruction (GSR) software. We compare then our results with GREM and with a complete Schwarzschild model. The study is finally completed by the reconstruction of a celestial sphere using 5 years of observations simulated with our model. These applications to astrometry are the result of the collaboration between the french group at SYRTE, responsible for the TTF and the italian one at OATO, responsible for RAMOD and GSR.
Lin Doug University of California, Santa Cruz, CA Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alessandro Sozzetti Origin, Evolution, and Destiny of Close-in Super Earths 2013-08-23 11:00:00 Seminar Link You Tube abstract
Planetary astrophysics is the most exciting and fastest growing branch of astronomy today. New data obtained from systematic radial velocity surveys and Kepler transit surveys have led to the discovery of nearly 900 planets and 3000 additional candidates, many of which are multiple systems. Although their presence is ubiquitous around nearby stars, their kinematic and structure properties appear to be diverse. Based on these rich data, I will present some theoretical analyses which may enable us to extract information about their origin, evolution, and structure. I will discuss the process of planet migration in evolving protostellar disks, the interaction of stellar magnetic fields with protostellar disks and close-in planets, tidal evolution of close-in companions, the potential retention of volatile elements and loss of atmosphere. These effects are incorporated into population synthesis models and the construction of scenarios for the retention of close-in planets, the observed obliquity between stellar spins and planet's orbits, density, and composition.
Antonio Stamerra INAF - Osservatorio Astrofisico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Claudia Raiteri Open issues from observations of TeV blazars. The MAGIC view and prospects with CTA. 2013-07-03 11:00:00 Seminar Link You Tube abstract
VHE observations (E>100 GeV) of Cherenkov telescopes together with the Fermi/LAT survey and multi-wavelength (MWL) simultaneous coverage are posing new challenges to the interpretation of the non-thermal processes in TeV blazars and AGNs. I will illustrate the most recent results threatening the conventional view of blazars, such as the difficulties of the usual description with single-zone SSC models of the SED of BL Lacs objects, the constraints on the location of the gamma-ray emission region and the interplay between intrinsic emission models and the interaction of gamma-rays with the extragalactic background light and intergalactic magnetic fields. In this talk these issues will be tackled in the framework of the results of MWL observations led by the MAGIC Cherenkov telescopes system and the prospects on CTA will be outlined. This will also be an occasion to report briefly on the activities connected to MAGIC and CTA in Turin.
Michele Piana Dipartimento di Matematica, Università di Genova Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Gianalfredo Nicolini Ricostruzione di immagini in STIX 2013-04-18 11:00:00 Seminar Link You Tube abstract
STIX (X-ray Spectrometer/Telescope - P.I. Säm Krucker, FHNW, Windisch, Switzerland) è uno strumento di Solar Orbiter che fornirà immagini iperspettrali di emissioni solari X, termiche e non-termiche. Al gruppo del prof. Piana è stata affidata la definizione e lo sviluppo del software scientifico di STIX. STIX in Solar Orbiter utilizza pattern di Moirè per misurare campionamenti sparsi della trasformata di Fourier della radiazione X dura emessa in corrispondenza di flare solari. In questo seminario verrà descritta la procedura di formazione del segnale e verranno discusse alcune tecniche di ricostruzione di immagini in corso di implementazione del software di analisi dati per STIX.
person_name1 person_surname Università di Torino, Dipartimento di Fisica Generale Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Anna Curir Measuring the dynamical properties of self­-gravitating systems in their outer regions through the caustic technique 2012-11-14 11:30:00 Seminar Link You Tube abstract
The caustic technique uses galaxy redshifts alone to measure the escape velocity profiles of galaxy clusters to clustrocentric distances beyond their virial radius, where dynamical equilibrium does not necessarily hold. This feature allows us to estimate the mass profile and to identify the members of galaxy clusters up to 4r200. We briefly review the available methods for estimating the mass profile and for identifying members in clusters and we focus on the analysis of the ability of the caustic technique to extract these dynamical properties. We study its possible systematic errors, by applying it to a large sample of simulated clusters with M200 larger than 10^14 Msun/h extracted from a cosmological hydrodynamical simulation of a LCDM universe.
ZhengHua Zhang Shanghai Astronomical Observatory, Chinese Academy of Sciences Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Richard Smart Discovery and characterization of ultracool dwarfs in large scale surveys 2012-10-26 11:00:00 Seminar Link You Tube abstract
Ultracool dwarfs are a mixture of low mass stars and brown dwarfs, they form the low mass end of mass function. They provide valuable insights into the efficiency of star formation. They represent fossilized records of star formation at all Galactic epochs. They also show what low-temperature atmospheres look like which could help us to understand atmospheres of gaseous planets. In my PhD I used the SDSS and UKIDSS surveys to search for ultracool dwarfs and their binaries and have found hundreds of ultracool dwarfs and tens of binary systems. In partircular I have focused on ultracool dwarfs with subsolar abundance from the halo, so called ultracool subdwarfs. I will present some of my latest results, including discoveries of M and L subdwarfs and their binary systems. Then I will discuss a few scientific topics related to ultracool subdwarfs, e.g. the halo substellar mass function, metal-poor ultracool atmospheres and Galactic kinematics.
Regina Soufli Lawrence Livermore National Laboratory, US Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Silvano Fineschi Multilayer optics for solar physics and astrophysics in the EUV/x-ray wavelength range 2012-10-16 11:00:00 Seminar Link You Tube abstract
This talk will discuss the development, fabrication and calibration of multilayer optics for solar physics instrumentation such as the extreme ultraviolet (EUV) imaging telescopes aboard NASA’s Solar Dynamics Observatory and aboard NASA/NOAA’s GOES-R space weather satellites. The presentation will also highlight the recent development of magnesium/silicon carbide (Mg/SiC) multilayers with corrosion barriers, which achieve high reflectance in up to 3 narrow bands simultaneously, in the 25-80 nm wavelength region. These triple-wavelength Mg/SiC multilayer coatings could be implemented with a combination of filters in a EUV solar imaging instrument, or used as part of a spectrometer. The development of a reflective/transmissive multilayer polarizer at 500 eV photon energy for the GEMS mission and grazing incidence optics for the NuSTAR hard x-ray astrophysics mission will also be discussed.
Roberto Susino INAF - Osservatorio Astrofisico di Catania Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alessandro Bemporad Recent results from SOHO/UVCS observations of two Coronal Mass Ejections 2012-09-27 11:00:00 Seminar Link You Tube abstract
The origin and early evolution of Coronal Mass Ejections (CMEs) is, at present, not fully characterized, although substantial progress has been made in the last two decades, after the launch of solar missions such as SOHO, TRACE, and STEREO. The determination of the 3-D structure and expansion (rotations and deflections) of CMEs is still an open issue, even if these knowledge drive the development of theoretical ideas and have also strong implications for predictive space weather applications. It is also widely accepted that CMEs are related to the magnetic reconnection process, but it is at present unknown how the energy release is triggered and how the post CME reconnection leads to the formation of stable and hot Current Sheets. In this talk, preliminary results will be presented on the analysis of two CME events, both observed with the Ultraviolet Coronagraph Spectrometer (UVCS) on board SOHO. The first event, that occurred on 2007 May 20, was a partial-halo CME associated with a prominence eruption ejected from an active region located approximately at the disc center, and with a B9 class flare. The 3-D structure and kinematic of the CME is studied using data acquired by SOHO/LASCO C2 and UVCS, and the COR1 coronagraphs and EUVI telescopes on board STEREO. The second event occurred on 2004 July 28 and was a partial-halo CME associated with a C1 class flare at the west limb. The analysis focuses on the evolution of the post CME current sheet, which is formed by the post-eruption magnetic reconnection and is responsible for a significant coronal emission in the "hot" Fe XVIII 974 Å spectral line observed in the UVCS data and for a relatively strong X-ray source observed off-limb in RHESSI and GOES/SXI data.
Amna Ali Saha Institute of Nuclear Physics, Kolkata (India) Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Ummi Abbas The Dark Side of the Universe 2012-07-11 11:00:00 Seminar Link You Tube abstract
An important challenge of cosmology is to understand the late time acceleration of the universe. High precision cosmological observations over the last decade suggest that about 73% of our universe's energy density is in the form of 'Dark Energy'. There are various models to describe Dark Energy. One of them is through Scalar fields. In my talk I will discuss about the Tachyon Dark Energy and the observational constraints on the model. Another way to explain the current epoch of acceleration is by modifying gravity at large scales. In the past few years, several schemes of large scale modifications have been actively investigated. I will also discuss about the f(R) gravity model and Galileon gravity.
Salvatore Capozziello Università degli Studi di Napoli Federico II - Dipartimento di Scienze Fisiche Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alberto Vecchiato Probing the Equivalence Principle at classical and quantum level 2012-06-22 11:00:00 Seminar Link You Tube abstract
After a critical discussion on foundation of gravitational theories, we consider the role of metric and geodesic structure, assumed to coincide in General Relativity. Relaxing this assumption, a wide range of gravitational theories is possible. To discriminate among them, fine measurements are necessary. We discuss a new space mission (STE-QUEST), proposed for ESA Cosmic Vision program, aimed to probe Equivalence Principle at classical and quantum level.
Luca Sorriso-Valvo Istituto per i Processi Fisico-Chimici, CNR, Rende (CS) Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Daniele Telloni Turbulence and intermittency in the solar wind: an overview 2012-06-13 11:00:00 Seminar Link You Tube abstract
Since the first spacecraft instruments provided is situ measurements of solar wind flow and magnetic field, it has been clear that interplanetary plasma is a highly turbulent medium. The turbulent fields fluctuations have been studied in the framework of magnetohydrodynamics (MHD), and a number of phenomenological prescriptions have been verified. Solar wind turbulence is intermittent, anisotropic, and strongly variable. However, it occasionally shows typical features of a MHD energy cascade, such as the linear scaling of the third order moments of the fluctuations. Today, the main hot topics are: (i) understanding the processes responsible for the dissipation of energy; (ii) the identification and description of turbulent structures; (iii) the universality of the cascade processes and relationship with the highly variable solar input. An overview of the state of the art is given here, together with some recent results. The importance of recent and future space missions for the understanding of solar wind turbulence is underlined.
Sam Krucker Institute of 4D Technologies, University of Applied Sciences Northwestern Switze Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alessandro Bemporad Hard X-ray Observations as Diagnostics of Particle Acceleration in Solar Flares 2012-06-08 11:30:00 Seminar Link You Tube abstract
Solar flares are powered by impulsive releases of magnetic energy stored in the corona. Hard X-ray and gamma-ray observations reveal that as much as half of the released energy goes into particle acceleration. The acceleration mechanisms that provide these efficient conversions of magnetic energy into supra thermal particles are currently not understood. In the past years however, significant progress has been made on the observational side; thanks in particular to observations by Reuven Ramaty High Energy Spectroscopic Imager (RHESSI), a NASA small explorer mission. After an extensive introduction, I will review recent observational results obtained by RHESSI. Furthermore, I will briefly describe future instrumentation such as the X-ray instrument STIX on board ESA’s Solar Orbiter mission and a sounding rocket experiment called FOXSI to be launch in 2012 that will test hard X-ray focusing optics for solar observations.
Giuseppe Murante INAF - Osservatorio Astrofisico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Giuseppe Murante Habitability of planets: the influence of their climate 2012-05-03 11:00:00 Seminar Link You Tube abstract
The circumstellar habitable zone is usually defined as the region around a star where a terrestrial planet, with an atmosfere having a pressure similar to the Earth's one,can have liquid water at its surface. This concept obviously depends on the planet's temperature. But if an atmosphere is present, the temperature is not the effective (black-body) one: we need a way to compute the surface temperature in presence of the atmosphere, and this means to study the planet's climate. With a simple climate model, a range of physical and astrophysical conditions can be explored. These includes axis inclination, orbital eccentricity, kind of star, rotation period, ocean coverage, greenhouse effect. I will show how one of this models, called EBM - Energy Balance Model - is particularly simple, well-suited to perform parameter space exploration, and easy to implement. I'll describe the model, our implementation, our changes with respect to the classical EBM already used in literature for these aims, and its validation using Earth's climate data. As an example I will show how the habitability of planets in the system GL581 can be influenced by their climate.
John Raymond Harvard-Smithsonian Center for Astrophysics (Cambridge, USA) Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Silvio Giordano Comet Lovejoy and other sungrazing comets 2012-04-11 11:00:00 Seminar Link You Tube abstract
A large family of comets known as the Kreutz sungrazers has been observed over the centuries. Because they pass very close to the solar surface, very few survive after perihelion. Comet Lovejoy in December 2011 was the first in several decades to be seen during egress, though 2000 have been seen in coronagraph images. It was detected in EUV images from the AIA instrument on SDO as well as coronagraph images. This talk discusses UV spectra of Lovejoy and other sungrazing comets from the UVCS instrument on SOHO, the physical processes involved, and inferences about the comets and the solar corona through which they pass.
Aldo Bonomo INAF - Osservatorio Astrofisico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alessandro Sozzetti Detection and characterization of transiting planets with the CoRoT and Kepler space missions: a deeper look into the physics of Jupiter-size and small-size planets 2012-02-23 11:00:00 Seminar Link You Tube abstract
With very high-precision photometry, the CoRoT and Kepler space missions allow us to characterize Jupiter-size planets with unprecedented precision and to find the optical planetary occultation which gives information on the planet equilibrium temperature and albedo. Besides that, by detecting small-size planetary candidates, they have triggered studies on the frequency of planets with radii between 2 and 4 Earth radii around solar-like stars. This is of fundamental importance for models of planet formation and evolution. I will present my recent works in this context.
Luca Casagrande Max-Planck-Institut fur Astrophysik, Garching, Germany Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Paola Re Fiorentin New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s) 2011-11-15 14:30:00 Seminar Link You Tube abstract
We present a re-analysis of the Geneva-Copenhagen survey, benefiting from the infrared flux method to improve upon the accuracy of the derived stellar effective temperatures and using the latter to build a consistent and improved metallicity scale. The new temperature and metallicity scales provide good match to theoretical isochrones, which are used for a Bayesian analysis of stellar ages. With respect to previous studies, the solar neighbourhood metallicity distribution function now peaks around the solar value. From Stromgren photometry we are able to derive for the first time a proxy for alpha abundances, which enables for a dissection of the chemical thin and thick disc. We find evidence for the latter being composed of an old, mildly but systematically alpha- enhanced population extending to super solar metallicities. The interpretation of these results in light of the physical processes relevant in the build-up of the Milky Way disc is addressed.
Filippo D'Ammando INAF-IASF Palermo Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Claudia Raiteri Multifrequency studies of radio-loud AGNs in the Fermi era. New discoveries and open questions. 2011-09-29 11:00:00 Seminar Link You Tube abstract
Since its launch in June 2008, the Fermi Gamma-ray Space Telescope has opened a new era in the studies of high-energy emission from Active Galactic Nuclei. Thanks to the unprecedented sensitivity, angular resolution and effective area of the Large Area Telescope, together with the nearly continuous observation of the entire gamma-ray sky, the Fermi-LAT has detected several hundred blazars and a few radio-galaxies, but also members of new classes of gamma-ray emitting AGNs such as the Narrow-Line Seyfert 1s and the Broad Line Radio Galaxies. When combined with simultaneous ground- and space-based observations Fermi-LAT achieves its fully capability to reach a deeper insight into the jet structure and the emission mechanisms at work in radio-loud AGNs. An overview of the study of gamma rays and multifrequency properties of these sources will be presented, highlighting major findings and open questions regarding the physics of AGNs in the Fermi era.
Marilena Mierla Institute of Geodynamics of the Romanian Academy, Bucharest, Romania Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alessandro Bemporad Three-dimensional reconstruction of coronal mass ejections 2011-05-26 11:00:00 Seminar Link You Tube abstract
In this presentation, we will describe different techniques that were used to model the 3D configuration of coronal mass ejections in the coronagraph field of view (up to 15 solar radii). We will focus on methods like: 1) Local correlation tracking (to identify the same feature in COR Ahead and COR Behind images) plus tie-point reconstruction technique; 2) Center of mass of the structures along the line of sight (i.e. along each epipolar lines) plus tie-point reconstruction technique; 3) Polarization ratio technique (see for e.g. Moran and Davila 2004); 4) Forward modeling technique (see Thernisien et al. 2006). Then, we apply these techniques to different CMEs observed by various coronagraphs. A comparison of results obtained from the application of different reconstruction algorithms is presented and discussed.
Irina Belskaya Institute of Astronomy, Kharkiv National University, Ukraine Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alberto Cellino Surface properties of small Solar system bodies from photometry and polarimetry 2011-03-24 11:00:00 Seminar Link You Tube abstract
An opposition effect in brightness and the negative branch in the degree of linear polarization are common phenomena observed at small phase angles for different types of minor bodies. Both opposition phenomena are considered to have similar physical nature and their joint analysis can put constraints on physical characteristics of the surface regoliths. An overview of photometric and polarimetric observations with emphasis on phase angle effects will be given for a variety of small Solar system bodies, including asteroids, Trojans, Centaurs and transneptunian objects.
Olja Panic ESO - Garching, Germany Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alessandro Sozzetti Observable signatures of dust evolution mechanisms which shape the planet-forming regions 2010-10-21 11:00:00 Seminar Link You Tube abstract
The first step towards forming planets happens at a very small scale: micron sized dust has to grow to millimetre sizes and far beyond that, to kilometer-sized planetesimals. As the dust grows it settles toward the disc midplane and drifts toward the star. These processes can lead toward overdensity of dust with respect to the gas in the planet forming regions, crucial prerequisite to form larger bodies and eventually planets. It is challenging to probe the physical conditions in the dense planet-forming regions observationally. We explore using the observations of outer disc as proxy for the dust evolution mechanisms expected to be at play in the inner disc. We use a state-of-the-art code to simulate dust evolution processes in gas-rich circumstellar discs. We explore varying disc sizes (250, 500, 1000AU) masses (0.1-0.01Msun) and dust properties (fragmenting velocity 1-10 m/s). Viscous gas evolution is included. Our models predict detectable differences in the radial distribution of dust with respect to the gas as early as 1-2Myr. These differences are caused by the dust drift process, and are most pronounced for fragmentation velocities close to 10m/s. Our modelling shows how apparent discrepancies between gas and dust distribution in disc, suggested by the current observations with interferometric arrays of antennas, can be explained in terms of dust evolution. Using the Atacama Large Sub/Millimetre Array (ALMA) simulator tool and the molecular excitation and radiative transfer code RATRAN we produce disc images in dust continuum and molecular lines. Our simulations show that with ALMA we will be able to assess whether there is a true depletion of dust from the gaseous outer disc regions or not, thus providing important clues to how dust evolves in discs.
Richard Frazin University of Michigan - Dept. of Ocean, Atmospheric and Space Sciences Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Lucia Abbo EUV and White Light Tomography of the Sun's Corona 2010-09-17 14:30:00 Seminar Link You Tube abstract
White light and EUV tomography, specifically differential emission measure tomography (DEMT), are discussed. They key role of deconvolution of the EUV instrument point-spread-function is explained. Applications to modeling and future directions are discussed.
Berry Holl Lund Observatory Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Ummi Abbas Characterizing the astrometric errors in the Gaia catalogue 2010-06-30 11:00:00 Seminar Link You Tube abstract
ESA’s space astrometry mission Gaia is expected to provide the most comprehensive and accurate catalogue of stellar positions, proper motions and parallaxes for galactic and astrophysical research in the coming decades. Accurate characterization of the errors in the catalogue is essential for making optimal use of the data. Therefore we investigate the structure of the covariance between the estimated astrometric parameters (which contains the standard errors and mutual correlations of the parameters). We present an initial simple model for the covariances and will compare this with statistical Monte Carlo estimates from our scalable simulation tool AGISLab. We will briefly talk about AGISLab which implements the baseline method for determining the astrometric parameters of Gaia stars, called the Astrometric Global Iterative Solution (AGIS). AGISLab is specialized in using a reduced number of stars (roughly 10K to 1M) and making many solutions for different noise realizations. To do so, it has its own 'scanner' that computes the observations of any input set of stars. Since AGISLab uses a scaling that preserved certain key quantities like the number of transits during the mission, its results can be extrapolated to a full size AGIS solution of many millions of stars.
Luigi Sertorio Universita' di Torino Planetario del Parco Astronomico di Pino Torinese, sala planetario Ester Antonucci Allometria e Astrobiologia 2010-05-29 15:00:00 Seminar Link You Tube abstract
Una stella è un sistema dinamico complesso, dissipativo, non lineare, confinato, energeticamente aperto, tale che il suo stato stazionario è caratterizzato da una potenza. Lo stato stazionario di una stella è la piattaforma temporale più lunga che si conosca. Analogamente un organismo vivente è un sistema complesso confinato ed è caratterizzato da una potenza. L'insieme degli organismi, la biosfera, ha proprietà di permanenza temporale paragonabile a quella di una stella. Per tali sistemi complessi diversissimi esistono tuttavia leggi allometriche, o di similitudine, che li accomunano. Queste leggi creano un ponte formale fra le stelle (che vediamo) e le possibili realizzazioni di vita cosmica (delle quali ne conosciamo una sola). Uno studio recente propone una legge allometrica per le coppie Stella-Pianeta che ci permette di uscire dal limite eliocentrico, cioè la coppia Sole-Terra della quale siamo parte.
Anna Nobili Universita' di Pisa Planetario del Parco Astronomico di Pino Torinese, sala planetario Anna Nobili General Relativity Tests from Space 2010-05-05 15:00:00 Seminar Link You Tube abstract
The discovery of Dark Energy and the fact that only about 5% of the mass of the universe can be explained on the basis of the current laws of physics have led to a serious impasse.
Francesco Paresce IASF Bologna Planetario del Parco Astronomico di Pino Torinese, sala planetario Ester Antonucci Star Formation in Nearby Super Star Clusters 2010-04-26 15:00:00 Seminar Link You Tube abstract
Super star clusters (SSC) play a dominant role in the formation and evolution of active galaxies at early epochs of their assembly and today in colliding and merging galaxies. A good understanding of the star formation process in SSCs is therefore crucial for clarifying the important role that the large number of very young stars play in the origin and fate of these clusters. In particular, the accurate study of the cluster's stellar mass function and its evolution in time allows us to determine whether or not the SSC quickly dissolve or survive to become the globular clusters we see today. With the new WFC3 camera on HST, we have carefully observed two of the closest SSC in our neighborhood:NGC 3603 and 30 Doradus. In this talk, I will describe these very recent observations and discuss some of the implications of the results.
Olindo Zanotti Max Planck Institute for Gravitational Physics, Potsdam, Germany Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Gianluigi Bodo Electromagnetic counterparts of recoiling black holes 2010-04-20 14:30:00 Seminar Link You Tube abstract
A strong motivation for studying the merger of supermassive binary black hole systems comes from the fact that their gravitational signal will be possibly detected by the planned Laser Interferometric Space Antenna (LISA), whose optimum sensitivity is placed in the range (10^{-4} - 0.1) Hz. Considerable attention has therefore been recently attracted by the possibility of detecting also the electromagnetic counterpart of these events through the emission coming from the circumbinary accretion disc that is expected to form when the binary is till widely separated. I will show the results of two-dimensional general relativistic hydrodynamics simulations of extended non-Keplerian circumbinary discs that responds to the loss of mass and to the recoil velocity of the black hole produced by the merger event. In contrast with what done in similar works, I question the estimates of the bremsstrahlung luminosity when computed without properly taking into account the radiation transfer, thus yielding cooling times that are unrealistically short. At the same time I show, through an approximation based on the isothermal evolution, that the luminosity produced can reach a peak value above L = 10^{43} erg/s at about 30 days after the merger of a binary with total mass M = 106 solar masses, and persist for several days at values which are a factor of a few smaller. The analysis has taken advantage of a new technique to construct a "shock detector", thus determining the precise location of the shocks produced in the accreting disc by the recoiling black hole. Future investigations implying the solution of the radiation hydrodynamics equations in the relativistic regime will be mentioned.
Angioletta Coradini IFSI, Roma Planetario del Parco Astronomico di Pino Torinese, sala planetario Ester Antonucci Planetary Satellites: structure and formation 2010-03-12 15:00:00 Seminar Link You Tube abstract
The satellite systems of Jupiter, Saturn and Uranus have been considered as miniature planetary systems since a long time. While they exhibit very diverse features, their study greatly helped to improve our understanding of the behavior of complex systems formed around a central body in terms of dynamical and physical properties. The regular satellites, which experience negligible solar perturbations, display dynamical properties similar to those of the planets. Moreover, the regular satellites are thought to have formed around their respective planets through a process similar to the one hypothesized for the accretion of the planets around the Sun. Any theory of the origins and evolution of the Solar System must then account for the presence and properties of satellite systems. When studying the origins of the satellites, we cannot avoid putting them in the context of the formation scenarios of their central planets. In fact, it is difficult to imagine satellite formation as totally independent from the environment generated and strongly affected by the central body. However, one has also to take into account that the formation times of the satellites are very short compared to those of their central bodies, and it is therefore possible for several generations of satellites to exist, each formed under different environmental conditions. One of the main contributions to the knowledge of the satellites has been given by the Space mission, Voyager, Galileo and Cassini. This last has been a real milestone in the understanding if Saturn system. The most important achievements of this mission will be discussed. In this presentation we will review the main discoveries of Cassini in the study of the satellites of Saturn. In particular we will discuss recent discoveries on Phoebe, Titan, Enceladus and Iapetus. The Cassini mission was the first case in which the Italian planetology community was directly involved developing state of the art hardware for a NASA mission.
Ralph Schonrich Max-Planck-Institut fur Astrophysik, Garching, Germany Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alessandro Spagna Understanding the Galactic disc(s) 2010-03-11 11:00:00 Seminar Link You Tube abstract
Throughout its history chemical evolution modelling of disc galaxies always relied on the assumption that as a valid approximation discs can be divided into concentric rings exhibiting highly independent evolution. I will show how the local metallicity distribution commands the existence of significant stellar radial migration. The immigration of old and kinematically hot inner disc populations into the solar neighbourhood gives rise to a thick disc component matching all known observations of the Galactic thick disc and thus challenging its separate origin. Resolving the full observational space of chemistry, ages and kinematics, the model can serve to discover and analyse intrinsic biases e.g. in the determination of the local standard of rest.
Roberto Silvotti INAF - Osservatorio Astronomico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Roberto Silvotti Synergy between asteroseismology and exoplanet search 2010-03-04 11:00:00 Seminar Link You Tube abstract
Asteroseismology and exoplanet search have similar observational techniques. Moreover, the timing method (either using pulsations or eclipses as a clock) is proving to be an interesting way to detect planets around evolved compact stars, for which RVs and transits are less efficient due to the high gravities and small radii. In this context, I will present an updated overview of the subdwarf B (sdB) + giant planet system V391Peg and discuss the potential of Corot and Kepler to search for planets with the timing method and to measure the secular variation of the pulsation periods. The presence of planets/BDs around three extreme horizontal branch (EHB) stars suggest that sdB planets could be a common phenomenon: substellar objects might play a role near the RGB tip, when a huge mass loss occurs to form an sdB star.
Bianca Garilli INAF - IASF Milano Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Ummi Abbas The VVDS project: closing up and lessons learned 2010-02-02 11:00:00 Seminar Link You Tube abstract
The VVDS project was born 15 years ago, with the purpose of studying galaxy formation and evolution as well as Large Scale Structures up to z~2 and beyond. With this purpose in mind, we have built the VIMOS spectrograph at the VLT, and used the Guaranteed Time to carry out the VVDS survey. After six years from the first observations, an assessment can be made on the scientific return, but also on the "educational" return. In this talk, I'll trace the story of the project, and illustrate a couple of the main results on galaxy formation and LSS evolution. I'll also present some considerations on what big collaborations, as VVDS has been, can give to young astronomers.
Remo Ruffini Universita' la Sapienza (Roma) e ICRANet (Pescara e Nizza) Planetario del Parco Astronomico di Pino Torinese, sala planetario Ester Antonucci Gamma Ray Bursts, Buchi Neri e Stelle di Neutroni 2010-02-01 15:00:00 Seminar Link You Tube abstract
Dalle recenti osservazioni dei Satelliti Fermi e SWIFT, che fanno seguito alle osservazioni pionieristiche dei satelliti Vela dell'osservatorio Compton ed i risultati epocali del satellite Beppo-Sax, si sta identificando una struttura standard dei Gamma Ray Bursts. Queste osservazioni permettono di esplorare regimi finora sconosciuti sia in Fisica che in Astrofisica e stanno conducendo ad una revisione di alcuni concetti fondamentali delle Stelle di Neutroni e dei Buchi Neri. Gamma Ray Bursts, Black Holes and Neutron Stars. A standard Gamma Ray Burst profile is surfacing from the recent observations of Gamma Ray Bursts by the Fermi and Swift Satellites, following the pioneering observations of the Vela satellites, the Compton mission and the epocal Beppo-Sax satellite. These observations are opening new theoretical understanding and bring observations in totally new regimes in the Physics and Astrophysics of Neutron Stars and Black Holes .
Seung-Hoon Cha Department of Physics & Astronomy, University of Leicester Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Giuseppe Murante Godunov SPH : the reality of simulations 2009-12-16 11:00:00 Seminar Link You Tube abstract
The Godunov SPH (Cha et al. 2009 and Inutsuka 2002, hereafter GSPH) has been revisited in terms of the consistency of a numerical scheme. The consistency is an essential property for the convergence of a numerical scheme. However, the standard SPH losses the consistency across a high density gradient, and shows an unphysical force at the contact discontinuity. The numerical surface tension appears due to the unphysical force, and damps the physical instability (Agertz et al. 2007). We will show that GSPH has the consistency even in a high density gradient, and can describe the Kelvin-Helmholtz instability. The Rayleigh-Taylor instability has also been performed to show the effect of the numerical surface tension. Other advantages of GSPH, for example, numerical dissipation (artificial viscosity or conduction) and tensile instability will be discussed in this presentation.
Silvio Bonometto Università degli Studi di Milano - Bicocca Planetario del Parco Astronomico di Pino Torinese, sala planetario Ester Antonucci Cosmologia moderna e post-moderna 2009-11-30 15:00:00 Seminar Link You Tube abstract
Il trapasso dalla cosmologia culturale alla cosmologia scientifica, avvenuto gradualmente, ha significato il progressivo contrarsi del contenuto ideologico della cosmologia, fino a farla divenire una parte della fisica e dell'astrofisica, basata cogentemente sui dati. Cio' non impedisce di individuare precisi nessi tra cosmologie pre-scientifiche e moderna cosmologia. Anzitutto nelle motivazioni del ricercatore (nesso soggettivo), che decide di investire il suo tempo e le sue risorse ad approfondire ipotesi a priori arbitrarie. E' chiaro che tali ipotesi non divengono scienza se non quando gli aspetti teorici e quelli sperimentali hanno raggiunto una completa mutua saturazione. Il fatto tuttavia non e' scevro da implicazioni, dal momento che i moderni progetti richiedono crescenti risorse, e la loro concessione da parte degli enti di ricerca e' anche basata sulla assonanza ideologica con le ipotesi proposte. Esiste poi un'importante corrente di pensiero che mira a recuperare, sulla base delle scoperte della moderna cosmologia, gli elementi portanti delle cosmologie tradizionali. Verranno esaminati gli strumenti utilizzati nella costruzione di questo ipotetico "nesso oggettivo", discutendo brevemente dei legami tra varie cosmologie tradizionali come quella vedica, quella sinica, nonche' le cosmologie biblica e kaballistica.
Michele Bellazzini INAF - Osservatorio Astronomico di Bologna Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alessandro Spagna The formation of stellar nuclei in vivo: the case of the Sagittarius dwarf galaxy and M54 2009-06-04 11:00:00 Seminar Link You Tube abstract
I discuss the latest observational findings about the nuclear region of the nearby dwarf spheroidal galaxy in Sagittarius, in the context of the theories of the formation of stellar nuclei and of Central Massive Objects. We have found evidence supporting the hypothesis that this galaxy was able to form its nucleus from two independent channels, i.e. by a localized star formation episode at the bottom of its potential well and by driving the massive globular cluster M54 to the same place by dynamical friction. Finally I will discuss new photometric and kinematic observations suggesting that a IMBH could be present at the center of M54.
Daniel Hestroffer IMCCE/Paris Observatory, Paris, France Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alberto Cellino Astrometry of asteroids to learn about their physical properties 2009-05-27 11:00:00 Seminar Link You Tube abstract
Asteroids are some of the closest and more accessible remnant material of the formation of our Solar System. Thanks to on-going observing surveys the number of discovered small bodies is increasing regularly. Since the last decades, and the progress made in particular in high angular resolution techniques, their name has become misleading: while stellar-like at the origin of their discovery and treated as point-like sources, they are now considered as geological bodies (some of them being dwarf planets). Moreover, since the discovery of satellite of asteroids, they now appear as small worlds on their own. One fundamental, and often not well known parameter is the mass of the asteroid. There are two main and direct ways for deriving this mass, both involving measure of positions, i.e. astrometry. The first method to have been used in the past involves the deflection due to mutual perturbations during a close encounter of a target asteroid (or space probe as well) with a more massive one. The second, much well known but applied only recently to asteroids, involves the presence of one or more satellites (natural or not). Conversely the mass can be inferred indirectly from the size and bulk density, if these are known. But this is often not the case and we will see some limitations to the density estimations from physical aspects. Additionally high accuracy astrometry of asteroids can bring  other information such as on light-scattering on their surface through the measure of the photocenter offset, or linking of the dynamical and kinematical reference frames. I will present the two direct methods for mass determination, with results already obtained from ground-based observations and results expected from the astrometric space mission Gaia, as well as future observations with 'big' telescopes (e.g. HST, Keck, VLT, etc.). A brief overview of the Gaia mission and instruments will be given, showing some aspects particular to solar system bodies observations by Gaia, including advantages and limitations. A method of orbit determination or inference by statistical inversion for binaries with small number of observations will be developed. We will then see how the knowledge of mass and bulk density can led to information on the asteroids interior.
Piero Galeotti Politecnico di Torino, Dipartimento di Fisica Planetario del Parco Astronomico di Pino Torinese, sala planetario Ester Antonucci Neutrino astrophysics: latest results 2009-05-25 15:00:00 Seminar Link You Tube abstract
Not Available.
Giovanna Tinetti University College London Planetario del Parco Astronomico di Pino Torinese, sala planetario Ester Antonucci Exploring extrasolar words: from gas-giants to terrestrial planets 2009-04-27 15:00:00 Seminar Link You Tube abstract
In the past decade, almost 300 planets orbiting other stars (extrasolar planets) have been discovered. For a growing sample of giant extrasolar planets orbiting very close to their parent star (hot-Jupiters), we can already probe their atmospheric constituents using transit techniques. With the primary transit method, we can indirectly observe the thin atmospheric ring surrounding the optically thick disc of the planet –the limb- while the planet is transiting in front of its parent star. With the secondary transit method, we can collect photons emitted or reflected by the planet. In our talk, we will focus in the most recent detections of water vapour and other carbon-bearing molecules in the atmospheres of hot-Jupiters using photometry and spectroscopy measurements with the Hubble and Spitzer space telescopes. The next generation of space telescopes, such as the James Webb Space Telescopes or SPICA, will allow us to probe the exoplanet atmospheres with higher spectral resolution and observe planets down to the Super-Earth size. Further into the future, new mission concepts from the space or the ground, will focus on the direct imaging and spectroscopic characterisation of Earth-like planets in the habitable zone of solar-type stars.
Sandro Caranzano Universita' di Torino, Dip. Filologia Linguistica e Tradizione Classica Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Maria Crosta Problematiche e prospettive di archeostronomia: il Disco di Nebra, una mappa del cielo di oltre 3500 anni fa 2009-04-16 11:00:00 Seminar Link You Tube abstract
Nel corso dell'incontro verranno presentate le modalità di scoperta, recupero e restauro di un eccezionale disco in bronzo con applicazioni in rame scoperto in Alta Sassonia ed attualmente conservato nel Museo di Halle (DE). Il disco conferma una serie di sospetti già maturati nell'ambito della comunità scientifica in merito a presunte conoscenze astronomiche nelle popolazioni del neolitico e dell'età dei metalli europei. Nello specifico, verra proposto un inquadramento culturale del disco dal punto di vista contestuale cercando di ricostruire la complessa simbologia - spesso astrale - che attraversa interculturalmente l'Europa preistorica e protostorica (dalle civiltà di Unetice, al mondo celtico fino a quello Etrusco). Il disco rappresenta un interessante spunto per lo studio e la rivalutazione critica di una ampia serie di segni archeologici che parrebbero avere un pregnanmte significato astronomico; nello specifico alcune tipologie di incisioni rupestre e alcuni complessi megalitici ben rappresentati nel terrorio alpino e perialpino
Rita Bernabei Università di Roma "Tor Vergata" - INFN Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Ester Antonucci Signals from the dark Universe 2009-04-02 11:00:00 Seminar Link You Tube abstract
DAMA is an observatory for rare processes which develops and uses several low-background set-ups at the Gran Sasso National Laboratory of INFN. This talk will be focused on the second generation DAMA/LIBRA set-up (about 250 kg highly radiopure NaI(Tl)) and on its recent activities to further investigate the presence of Dark Matter particles in the galactic halo by exploiting the Dark Matter annual modulation signature. Here the first results obtained by this second generation experiment are presented (exposure of 0.53 ton x yr). DAMA/LIBRA data confirms the model independent evidence for the presence of Dark Matter particles in the galactic halo as observed by the former DAMA/NaI experiment. The combined analysis of the data of the two experiments (total exposure 0.82 ton x yr) gives a C.L. at 8.2 sigma. Implications and perspectives will be addressed.
Bruno Gardini ESA Planetario del Parco Astronomico di Pino Torinese, sala planetario Ester Antonucci ESA Human Spaceflight and Exploration Programmes 2009-03-30 14:30:00 Seminar Link You Tube abstract
With the Columbus module an integral part of the International Space Station (ISS) since February 2008 and the first flight of the Advanced Transport Vehicle (ATV)- Jules Vernein April 2008 successfully beyond us Europe has become a recognized partner in the Human access to Low Earth Orbit (LEO). In 2009 the ESA astronaut Frank De Winne will be the first European Commander of the ISS, with a full Crew of six astronauts and cosmonauts. In the mean time traditional human spaceflight Nations (USA, Russia) as well as emerging countries (China, India) have declared themselves in favour of long term operations in LEO and extended Lunar exploration, ultimately resulting in a permanent Lunar Basis. It is now time for Europe to move forward and face the new challenges of Human Exploration beyond LEO. This includes an Advanced Re-Entry Vehicle (ARV), with the capability to up and downloading cargos to the ISS and later on evolve into a crew transportation vehicle. The next milestone is the International Moon Exploration programme, under the US leadership, where Europe may participate with a Lunar Cargo Lander as an integral part of the NASA Altair Mission, planned to be launched in 2020.
Mauro Rajteri INRIM - Istituto Nazionale di Ricerca Metrologica Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Mario Lattanzi Conteggio di fotoni nell' UV-visibile con rivelatori superconduttivi 2009-03-19 11:00:00 Seminar Link You Tube abstract
Nell'ultimo decennio c'è stato un forte sviluppo nel campo dei rivelatori a singolo fotone. In particolare i rivelatori basati su dispositivi superconduttivi hanno dimostrato di essere in grado di estrarre dai fotoni rivelati un maggior numero di informazioni rispetto ai rivelatori basati su semiconduttori. Alcuni rivelatori superconduttivi quali le Superconducting Tunnel Junctions (STJ) e i Transition-Edge Sensors (TES) hanno la capacità di avere una risoluzione energetica intrinseca, cioè di misurare l'energia del fotone rivelato, e di discriminare il numero di fotoni contenuti in un impulso. Nel seminario verranno presentati i risultati ottenuti presso l'INRIM con TES basati su film di titanio. Con questi rivelatori, che funzionano come microcalorimetri, è stato possibile distinguere singoli fotoni tra 200nm e 800nm, e, lavorando con un laser a 690 nm, distinguere fino a 5 fotoni contenuti in un impulso di luce.
Ugo Becciani INAF - Osservatorio Astrofisico di Catania Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alberto Vecchiato Risorse di calcolo nell'Infrastruttura del Sud Italia e metodi di visualizzazione per problemi computazionalmente complessi 2009-03-12 11:00:00 Seminar Link You Tube abstract
La nuova infrastruttura computazionale nel Sud Italia è in grado di offrire nuove prospettive e importanti risorse nel contesto nazionale, sia per applicazioni scientifiche che industriali. Sarà presentata l'infrastruttura del Consorzio Cometa costituita con il progetto PI2S2, il suo stato attuale e le nuove sfide, soprattutto nel settore del calcolo ad alte prestazioni. Una parte essenziale della ricerca astrofisica, soprattuto per chi ha necessità del calcolo ad alte prestazioni, è data anche dalla necessità di utilizzare strumenti di grafica e visualizzazione di dati multidimensionali sia da catalogo che da complesse simulazioni numeriche. In questa prospettiva è stato sviluppato VisIVO, una applicazione C + + specificamente progettata per l'esplorazione di dati multidimensionali. Si tratta di un tool opensource disponibile per una varietà di piattaforme (MS Windows, GNU/Linux e MacOS). L'ultima versione di VisIVO supporta i più importanti e popolari formati di dati astronomici, senza limiti nella dimensione del dataset. VisIVO è in grado di esplorare sia dati multidimensionali osservativi che da simulazioni numeriche, quali dati da catalogo, sistemi n-corpi, campi su griglia ecc., dandone una rappresentazione sia come punti nello spazio multidimensionale che come volumi. Inoltre, esso incorpora funzionalità avanzate come calcolo di isosuperfici, la creazione e la visualizzazione di campi vettoriali, l'individuazione di outlayers ecc. Infine saranno presentate le nuovi componenti di VisIVO: il nuovo VisIVO Server e il nuovo VisIVO Website rappresentano uno strumento innovativo nell'analisi di dataset di grandi dimensioni.
Alessandro Capetti INAF - Osservatorio Astronomico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available Birth, life and death of radio-galaxies 2009-03-05 11:00:00 Seminar Link You Tube abstract
I will present an analysis of multiwavelength data (including HST, Chandra and optical spectroscopy) obtained for samples of radio-loud AGN aimed at exploring the mechanisms 1) leading to the birth of radio-galaxies, 2) that maintain the accretion onto the supermassive black hole during their lifetime and finally 3) that lead to the death of the AGN.
Frances Westall Centre de Biophysique Moléculaire-CNRS, Orléans Planetario del Parco Astronomico di Pino Torinese, sala planetario Ester Antonucci Exobiology, origin of Life in the Solar System 2009-02-23 15:00:00 Seminar Link You Tube abstract
Earth is the only planet in the Solar System we know of that hosts life. We dream about life on other planets – the life forms generally being portrayed as humanoid-like creatures in science fiction films – but what are the real chances that life could exist elsewhere within reach of human exploration? I will talk about the minimum conditions for life to appear on a planet and show that, throughout the history of the Solar System, and in its future, primitive life forms could have inhabited other planets, maybe still do, and probably will in the future. Mars is the most likely candidate, but Venus in its youth was habitable, and probably also certain moons of the giant gas planets, such as Enceladus around Saturn and Europa orbiting Jupiter. In the future, as the Sun grows larger and hotter, the habitable zone in which liquid water is stable at the surface of a planet will be shifted towards planets further away – and our own planet will end up like Venus.
Donata Bonino INAF - Osservatorio Astronomico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available Algoritmi di fringe sensing e modellizzazione di segnali per l'interferometria infrarossa 2009-02-19 11:00:00 Seminar Link You Tube abstract
La prima parte della presentazione è dedicata agli algoritmi di misura della differenza di cammino ottico (OPD) per i sensori di frangia FINITO e PRIMA FSU, costruiti per l'interferometro europeo VLTI (ESO). Particolare attenzione verrà posta sul modello di segnale interferometrico su cui gli algoritmi sono basati. Tale modello si è evoluto in complessità, grazie all'esperienza acquisita, per far fronte alla richiesta di prestazioni sempre più estreme. Bisogna tenere presente che l'analisi di frangia presenta problemi diversi rispetto all'utilizzo scientifico della curva di visibilità; gli stimatori di posizione sono pochi e le loro prestazioni dipendono dalle proprietà strumentali. Questa analisi mostra come le prestazioni degli algoritmi siano buone, ma che la relazione tra parametri di modello e fonti di rumore merita ancora approfondimenti. La seconda parte del seminario presenta i risultati dell'attività dedicata a questo scopo. La domanda che ci siamo posti è come verificare la presenza di un disturbo dovuto al processo di combinazione, e come quantificarlo. Per rispondere, abbiamo utilizzato metodi matematici e statistici raffinati: analisi di serie storiche, analisi di regressione. L'utilizzo attento di queste tecniche permette di dare una maggiore significatività a metodi ampiamente utilizzati, quali stime ai minimi quadrati. Abbiamo identificato anche alcuni strumenti statistici, ad esempio il test di Levene o la varianza di Allan, atti a valutare le prestazioni strumentali e le peculiarità del flusso in arrivo.
Fernando de Felice Dipartimento di Fisica "G.Galilei", Università di Padova Planetario del Parco Astronomico di Pino Torinese, sala planetario Ester Antonucci The Role of Time in cosmic puzzeles: Gamma ray burst, achronality and dark matter 2009-01-26 15:00:00 Seminar Link You Tube abstract
In the Theory of Relativity time and space play an equal role in fixing the space-time geometry. Treating the time dimension as a spatial one using the dimension converting factor given by the universal Maxwell's constant c one can extend to all particles the property of moving at the velocity c. This allows us to introduce a generalized principle of relativity which enhances the role of time as the primary cause of some of the most intriguing cosmic phenomena as the gamma ray bursts and gives hints to the very nature of dark matter.
Alberto Riva INAF - Osservatorio Astronomico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available IRAIT-AMICA, Infrared astronomy in Antarctica  2008-12-18 11:00:00 Seminar Link You Tube abstract
AMICA (Antarctic Multiband Infrared CAmera) is an instrument designed to perform astronomical imaging from Dome-C in the near- (1-5 micron) and mid- (5-27 micron) infrared wavelength regions. AMICA will be mounted at the Nasmyth focus of the 80 cm IRAIT telescope and will perform survey-mode automatic observations of selected regions of the Southern sky. The first goal will be a direct estimate of the observational quality of this new highly promising site for Infrared Astronomy. In addition, IRAIT, equipped with AMICA, is expected to provide a significant improvement in the knowledge of fundamental astrophysical processes, such as the late stages of stellar evolution (especially AGB and post-AGB stars) and the star formation.
Stefano Vitale University of Trento Planetario del Parco Astronomico di Pino Torinese, sala planetario Ester Antonucci LISA Pathfinder,LISA and Space-borne Astronomy 2008-11-24 15:00:00 Seminar Link You Tube abstract
The talk will review the technical status and the foreseen science return of LISA, the first space-borne gravitational wave observatory, and of LISA Pathfinder, the precursor to LISA currently under implementation by the European Space Agency (ESA). LISA science spans a comparatively large set of disciplines. It includes for instance the astrophysics of galactic binaries, from the most extended population census of white-dwarf and stellar mass black-holes to the study of mass transfer and tidal interaction in some of the brightest sources. It reaches to cosmology via the extremely bright signals from super-massive black-hole binaries that are visible throughout the entire universe and that give an independent cosmological distance ladder. It finally impacts on fundamental physics with, for example, the map of the black-hole event horizon that the signals from black-hole binaries will provide. These signals will allow us, among other things, to perform a detailed verification of Kerr geometry, including a test of black-hole uniqueness theorems and a measurement of the graviton mass. Finally LISA, and its fundamental intermediate step LISA Pathfinder, will considerably advance the science ofs pace-time measurements, an underpinning knowledge for any experiment in general relativity and gravitation.
Silvio Bonometto Università degli Studi di Milano - Bicocca Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Giuseppe Murante Cosmology & cosmologies 2008-11-20 11:00:00 Seminar Link You Tube abstract
This talk aims to trigger a debate on themes that any scientifical researcher always bears in mind, namely if he works in cosmology. As a matter of fact, all cultures, since ever, have had their own cosmology and allowed it their most advanced techniques. The first question concerns then the difference between modern and traditional cosmologies: what is conceptually new in it, apart of modern techniques? After focusing on differences, which marked quite a gradual transition, two kinds of questions keep open: Which influence had ideology, at the personal and social levels, on the development of cosmology? and the most intriguing question: Does modern cosmology allow to recover, starting from its authonomous assumptions, aspects belonging to the substratum that all traditional cosmologies have in common? The basis of this discussion is taken from 4 chapters of the book "Cosmologia & Cosmologie" recently appeared by Zanichelli.
Gianni Navarra Università di Torino, Dipartimento di Fisica Generale Planetario del Parco Astronomico di Pino Torinese, sala planetario Ester Antonucci La radiazione cosmica di alta energia 2008-10-27 15:00:00 Seminar Link You Tube abstract
Negli ultimi anni le misure nel campo della fisica cosmica di alta energia si sono notevolmente sviluppate. Ci si propone quindi di introdurre le tecniche di misura e presentare i recenti risultati ottenuti tramite gli esperimenti di ultima generazione: EAS TOP, KASCADE-Grande, Auger, nel range di energie tra 1015 eV ad oltre 1020 eV. I dati sperimentali riguardano lo spettro energetico, la composizione chimica, e le anisotropie nelle direzioni di arrivo dei primari. La regione energetica ricopre le energie estreme della radiazione galattica e la transizione alle sorgenti extra-galattiche. Le presenti segnature di questi effetti, e le indicazioni su sorgenti e processi di accelerazione, vengono discusse, con i problemi aperti e le prospettive sperimentali.
Magda Arnaboldi INAF - Osservatorio Astronomico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available The ESO public surveys with VISTA (Infrared) and VST (optical) 2008-09-24 11:00:00 Seminar Link You Tube abstract
A new chapter for European astronomy will soon begin with dedicated survey telescopes in the optical and near-infrared. These large collaborative surveys within Europe target many of the fundamental questions in astrophysics today, ranging from the nature of dark energy to the universality of the stellar initial mass function. I will present the Public Survey projects and give information on the mechanisms that ESO has set in place to manage them, to ensure their legacy value and their usefulness for the astronomical community at large.
Paola Re Fiorentin University of Ljubljana, Dept. Mathematics and Physics Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alessandro Spagna Classification and astrophysical parameter estimation for Galactic surveys using machine learning algorithms 2008-08-29 11:00:00 Seminar Link You Tube abstract
Studies of Galactic populations have long been limited by the small number of stars that could be confidently identified as members, and also by the lack of available spectroscopy from which radial velocities and estimates of atmospheric parameters could be obtained. This state of affairs is rapidly changing with the advent of large surveys; however, efficiently extracting scientific information from such huge databases becomes a critical and challenging problem. The classification of the wide variety of objects coming available requires automated and appropriate multi-dimensional data analysis techniques. I examine and test different supervised and unsupervised learning algorithms to classify observed objects and, once detected, determine precise/accurate and reliable intrinsic properties individually; better performances, able to deal with presence of noise and discovery of unusual data, are achieved by combining different methods. I present recent results and discuss various aspects of source classification and physical parametrization (effective temperature, surface gravity and metalicity, in particular) from SDSS-II/SEGUE and RAVE spectroscopy. Looking ahead, the techniques investigated form the basis for future ground/space missions classifiers essential for fully exploiting the catalogues with astrophysical information, obtain tracers for studying Galactic structures and hence constraining Galactic formation scenarios.
Jean Souchay Observatoire de Paris- Syrte Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alberto Cellino The ICRS: maintenance, densification and link with the dynamical system : the activities at SYRTE 2008-07-03 11:00:00 Seminar Link You Tube abstract
We discuss the activities related to the ICRS (International celestial reference System) done at Paris Observatory in the laboratory of SYRTE (SYstèmes de Référence Temps-Espace). Some of them concern the maintenance of the ICRF (International Celestial Reference Frame) which is the fundamental realization of the ICRS, and its densification through the astrometric measurements of quasars. Other ones concern the link with the dynamical system through the study of motions of the celestial bodies (close approaches quasars-planets, lunar laser ranging, pulsar timing referenced to the orbital motion of the Moon, follow-up of satellites as WMAP and GAIA) We will discuss in particular a recent study on close approaches between Jupiter and quasars, and the construction of the LQAC (Large Quasar Astrometric Catalogue).
Claudio Zanni Univeristy of Grenoble Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Gianluigi Bodo MHD simulations of magnetized accretion disks around young stars 2008-05-08 11:00:00 Seminar Link You Tube abstract
Nowadays there is a general consensus about the fact that large scale magnetic fields can play a crucial role in the context of star formation. As a first example, large scale magnetic fields threading a Keplerian disk rotating around the central star can launch magneto-centrifugally driven disk-winds. Moreover, it is likely that the accretion onto the surface of the star is controlled by the interacion of the accretion disk with the stellar magnetosphere. In this talk I will present MHD simulations of the interaction of large scale magnetic fields with accretion disks around young stellar objects. On one hand I will discuss the effects of an anomalous resistivity, parametrized through a Shakura & Sunyaev "alpha" prescription, on the launching mechanism of disk-winds. Looking on the other hand to the magnetic star-disk interaction, I will portray different "states" of interaction between the disk and the stellar magnetosphere, each of them characterized by different dynamical and observational features (accretion rates, variability). Moreover I will consider the torque exerted by the accretion disk on the magnetized star: I will show that a disk-locked configuration does not seem to be efficient enough to explain the stellar spin-down to the observed periods of rotation. Additional mechanisms associated to ejection phenomena (accretion powered stellar winds, megnetospheric ejections) must be therefore taken into account.
Angelo Tartaglia Politecnico di Torino, Dipartimento di Fisica Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Mario Lattanzi Dark matter/Dark energy: dark ages for cosmology? 2008-04-10 11:00:00 Seminar Link You Tube abstract
The observation of the luminosity of type Ia supernovae has convinced the community of astrophysicists and cosmologists that the universe is not only expanding but has started to do so in an accelerated way, sometime in the past. This discovery, which will be reviewed, has revived an old solution of the Einstein equations incorporating the so called cosmological constant. The physical interpretation of the solution introduces the idea of a peculiar homogeneous and isotropic "fluid" corresponding to a sort of dark energy, whose effect (at the moment) is only in the accelerated expansion. To this dark energy a number of apparently anomalous gravitational behaviours have added the impression that the universe contains also some kind of matter whose only effect is gravitational: this is what is usually meant by "dark matter". A number of theories, which will be shortly reviewed also, have been worked out, trying either to provide an interpretation of the dark energy and dark matter or to get rid of them. A new theory, the cosmic defect theory (or CD for short) will be proposed, treating space-time as a four dimensional continuum endowed with properties similar to the ones belonging to ordinary three-dimensional continua. The idea is that a defect in the four-dimensional continuum would induce in space-time a strained state, read, in our usual 3+1 view, as the accelerated expansion of the universe. The full Einsteinian framework is preserved; furthermore the theory proves to be able to fit the supernova luminosity data with an accuracy comparable to that of the so called standard dark-energy/dark-matter theory.
Adem Saglam LPAP-Laboratoire de Physique Atmosphérique et Planétaire Université de Liège Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Mario Gai Hypertelescopes in Space. 2008-03-27 11:00:00 Seminar Link You Tube abstract
Hypertelescopes are multi-aperture Fizeau interferometer systems with a pupil densification system at the exit. Preliminary studies on ground showed the power of hypertelescopes to do high resolution imaging. The mirrors of the hypertelescope need to be cophased very precisely to do direct imaging. I will show how the photonic propulsion may be used to cophase each mirror element for future in space hypertelescopes.
Mauro Barbieri LAM - Observatoire de Marseille Provence, Marseille (France) Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alessandro Sozzetti CoRoT some results and tools developed for spectral classification 2008-03-06 11:00:00 Seminar Link You Tube abstract
CoRoT is the first space mission dedicated to the detection of transiting extrasolar planets. In this talk I will show some highlights about the firsts results about exoplanets discovered with CoRoT and some ideas about the stellar populations of the CoRoT fields. More specifically I will present a tool developed for spectral classification of stars in the CoRoT FoV. During last years a large observational effort was done for the photometric characterization of the CoRoT observable fields. For the purpose of target selections, we have developed a bayesian method for estimation of stellar parameters and relative uncertainties from photometric data and theoretical isochrones. The method permit to obtain for each star the relative posterior probability density as a function of the parameter of interest (mass, radius, distance, etc.)
Roberto Silvotti INAF - Osservatorio Astronomico di Capodimonte Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Mario Di Martino Late stage evolution of planetary systems: the case of V 391 Pegasi b. 2007-12-06 14:30:00 Seminar Link You Tube abstract
Most of the ~250 extra solar planets presently known are hosted by main sequence stars similar to our Sun. When their core hydrogen runs out, main sequence stars undergo a red giant expansion that modifies the planetary orbits and can easily reach and engulf the inner planets. The fate of the inner planets during and after the red giant phase is largely unkown. In this talk we describe the detection of the first planetary-mass companion to a post-red giant star, orbiting the extreme horizontal branch pulsating star V 391 Pegasi at a distance of about 1.7 AU, with a period of 3.2 yr.
Salvatore Capozziello Dipartimento di Scienze Fisiche, Università di Napoli "Federico II" Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Maria Crosta Dark Energy and Dark Matter or Curvature Effects? 2007-11-15 11:00:00 Seminar Link You Tube abstract
Renato Pannunzio INAF - Osservatorio Astronomico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available Presentazione dei filmati "Il sogno di Icaro - Cinquant'anni di esplorazione dello spazio" e "Il Sestante" 2007-10-25 10:00:00 Seminar Link You Tube abstract
Not Available.
Paula Teixeira Harvard-Smithsonian Center for Astrophysics (USA), Universidade de Lisboa (Portu Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alessandro Sozzetti Footprints of hierarchical thermal fragmentation in the star forming cluster NGC 2264 2007-07-26 11:00:00 Seminar Link You Tube abstract
To fully understand how molecular clouds survive long enough to sustain multiple star forming epochs it is essential to know in detail their star forming histories. NGC2264 is one of the classical star forming regions, studied by Walker in 1965 who discovered its pre-main sequence (PMS) population. We re-visit the region with the Spitzer Space telescope to study in detail its PMS sources in terms of circumstellar disk evolution and age spread. Our analysis of the spatial distribution of the sources indicate that there were two distinct star epochs in NGC2264. I will briefly discuss the correlation between the spatial distribution and the age spread of distinct populations within NGC2264. The latest star forming event has spawned a cluster of protostars in NGC2264 (Spokes cluster) that retains a characteristic length scale (20"+-5") similar to the Jeans length for that region (27"). During this talk, I will present sensitive high angular resolution (~1") 230 GHz continuum interferometric observations of a submillimeter core, D-MM1, using the Submillimeter Array, in Hawai'i. We detected seven very compact millimeter sources clustered in a 20" x 20" region, two of which are associated with infrared emission. The seven new millimeter sources have ~0.8 solar masses and sizes of about 600 AU. We interpret these 1.3 mm sources as compact dense protostellar envelopes of Class 0 objects. The mean distance between these sources is 7" (~5000 AU) which is the same as the Jeans length for D-MM1. Comparison of the spatial scalings of the Spokes cluster and the micro-cluster in D-MM1 lead us to explore the scenario of a secondary thermal fragmentation within the region. Our analysis seem to indicate that the dominant fragmentation process for this region within NGC 2264 is thermal and not turbulent.
Alexandre Andrei National Observatory of Brazil Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Richard Smart Measurements of Solar Radius Variations. 2007-06-01 11:00:00 Seminar Link You Tube abstract
Variations of the solar radius are as unpredictable as puzzling. Most of the modern observations agree in that a companionship with the solar activity cycle is verified. However, the classical series from Calern (Delache et al., Nature 1985) seem to point out to a shifted phase as from the late 70's. On the other hand, on shorter temporal scales, is it representative the well documented case in 2001, where the amplitude and timing of the variation were shown to keep pace with a major solar event (Andrei et al., A&A 2004). Answers to such questions can be discussed from the series of daily solar diameter observations with the CCD Astrolabe at the Observatorio Nacional (ON). We will review the instrumentation and methods used, in the framework of the international monitoring network (R2S3). The measurements are firstly presented by focusing on the ON results around the maximum of solar cycle 23. In total, there are 18,066 independent observations, without seasonal interruptions and spanning all heliolatitudes. These observations are compared to five daily estimators of the solar activity: total irradiance, sunpots number, 10.7cm radio flux, flares index, and the integrated magnetic field strength. The comparisons are made in three stances: as regards to the smoothed time series, as regards to the peaks and dips correlation, and as regards to heliolatitude and cycle age dependencies. Next the data from the R2S3 are inter-compared in order to verify whether measurements taken at widely different observational conditions do agree and support the ON station results. Finally we present simple scenarios giving rise to the observed solar radius variations. The data are therefore in hands, and the work in progress, to tackle the starting questions: how and to what measure the solar radius and activity are to be compared? And, how often and to what measure the solar radius and events are to be compared.
Marc Fouchard LAL-IMCCE/Université de Lille 1, Observatoire de Lille Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Aldo Dell'Oro Dinamica a lungo termine delle comete della nube di Oort 2007-05-03 11:00:00 Seminar Link You Tube abstract
Le comete a lungo periodo vengono probabilmente dalla nube di Oort che costituisce la parte piu' esterna del Sistema Solare. In questa regione le traiettorie delle comete sono influenzate in particolare dalla marea galattica e dalle stelle che passano vicino al Sistema Solare. La simulazione della dinamica delle comete della nube di Oort su un periodo di 5 miliardi di anni e' presentata tenendo in conto i diversi meccanismi che perturbano il loro moto. Da una parte, la marea galattica produce una dinamica quasi integrabile, permettendo una spiegazione semplice del flusso di comete dalla nube verso la regione planetaria del Sistema Solare; dall'altra, le perturbazioni stellari costituiscono una perturbazione stocastica che produce ogni tanto incrementi del flusso di comete, chiamate docce cometarie. Questi diversi meccanismi saranno dunque presentati e descritti.
Alessandro Sozzetti INAF - Osservatorio Astronomico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Aldo Dell'Oro The Connection Between Stars, Planets, and Metals: A Nail in the Coffin for Heretic Theories of Giant Planet Formation? 2007-04-26 11:00:00 Seminar Link You Tube abstract
The planet-metallicity connection is one of the most important aspects of the close relationship between characteristics and frequencies of planetary systems and the physical properties of the host stars which have been unveiled by the present sample of over 200 extrasolar planets. In particular, the likelihood of finding a planet around a given star rises sharply with stellar metallicity. Furthermore, a correlation may also exist between estimated inner core masses of transiting giant planets and the hosts' metal content. In both cases, the evidence collected so far appears to strongly support the orthodox mechanism of giant planet formation by core accretion, as opposed to the heretic formation mode by disk instability. However, the relatively small numbers of metal-poor stars screened for planets so far, and the large uncertainties often present in the determination of both planet and stellar properties in transiting systems prevent one from drawing conclusions. I will describe two experiments designed to put the observed trends on firmer observational grounds, thus ultimately helping to discriminate between proposed planet formation models. First, I will present results from a Doppler survey for giant planets orbiting within 2 AU of a well-defined sample of 200 field metal-poor dwarfs. Our data will crucially help to gauge the behavior of planet frequency in the metal-poor regime. Then, I will describe a novel method for improving on the knowledge of stellar and planetary parameters of transiting systems through a careful analysis of spectro-photometric measurements. With this approach, structural and evolutionary models of irradiated planets can be better informed, allowing for refined estimates of the heavy-element content of transiting planets and for improved understanding ot the core mass - stellar metallicity correlation.
Pier Moretti Università "La Sapienza" di Roma, Dipartimento di Scienze della Terra Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available L'alterazione delle superfici degli asteroidi e loro effetti sullo spettro nel visibile e vicino infrarosso. 2007-04-20 11:00:00 Seminar Link You Tube abstract
L’associazione tra meteoriti e corpi progenitori e' fondamentale per la comprensione della formazione del sistema solare e dei pianeti maggiori. Infatti lo studio delle meteoriti fornisce principalmente la distribuzione dell’evoluzione temporale delle condizioni fisiche presenti nel sistema solare, e i corpi progenitori ne stabiliscono la distribuzione spaziale. Mentre lo studio delle meteoriti si avvale di innumerevoli analisi che forniscono informazioni dal punto di vista mineralogico, petrologico e fisico, per i corpi celesti le informazioni si ottengono principalmente dallo studio degli spettri della luce riflessa in remoto. La classe piu' abbondante delle meteoriti, le condriti ordinarie, e' stata associata alla classe di asteroidi anch’essa piu' abbondante, chiamata tipo S, dal paragone tra gli spettri nelle regioni del visibile e vicino infrarosso (NIR). Tuttavia, tale associazione e' a tuttoggi dubbia, in quanto molti degli spettri degli asteroidi risultano arrossati, ovvero con una maggiore riflettivita' nel NIR. Durante il seminario verranno presentati i risultati relativi allo studio di quei processi fisici che possono provocare un'alterazione delle superfici dei corpi celesti in assenza di atmosfera e delle loro conseguenze nell’arrossamento dello spettro. Lo scenario delle interpretazioni di tale arrossamento e' stato recentemente arricchito di nuove proposte, ma cio' nonostante, il problema dell’arrossamento degli asteroidi S non e' ancora risolto. A riguardo, la comunita' scientifica ripone grandi aspettative dai risultati della missione Hayabusa, che alla fine del 2005 ha permesso ad una sonda spaziale si posarsi sulla superficie di un asteroide S e prelevare campioni che dovrebbero essere riportati sulla Terra nel giro di pochi anni. In questo contesto, e' stato stipulato un accordo formale per lo sviluppo di un progetto triennale (dal 2006 al 2008), di cui il Dott. Pier Francesco Moretti e' Principal Investigator, con lo scopo di sviluppare tecniche e strumentazione per l’analisi di campioni extra-terrestri (progetto ETNA, in collaborazione con il Dipartimento di Scienze della Terra dell’Universita' di Roma "La Sapienza", l’Istituto di Struttura della Materia del CNR, il Dipartimento di Fisica dell’Universita' di Roma Tre, l’Istituto di Fisica dello Spazio Interplanetario e l’Osservatorio Astronomico di Torino dell’INAF).
Vincenzo Zappalà INAF - Osservatorio Astronomico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Aldo Dell'Oro 99942 Apophis: possiamo evitare la fine del mondo? 2007-03-21 11:00:00 Seminar Link You Tube abstract
Anche se solo dopo più di tre anni dalla scoperta, le notizie relative all’asteroide Apophis, in possibile rotta di collisione con la Terra, sono apparse sui "mass media". Al di là del rischio effettivo, il caso Apophis è un ottimo banco di prova per comprendere i "veri" problemi sia scientifici che soprattutto politici legati ad un evento catastrofico di questa portata (quasi sicuramente mai subito dal genere umano) e per pianificare correttamente le possibili azioni da intraprendere per evitarlo. Anche se su tempi scala decisamente "non politici", l'impatto con un asteroide è una delle poche certezze nel futuro della Terra ed una buona conoscenza del problema è il minimo che si possa richiedere ai governi del nostro pianeta.
Stefano Cristiani INAF - Osservatorio Astronomico di Trieste Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Giuseppe Murante The CODEX-ESPRESSO Experiment: Cosmic Dynamics, Fundamental Physics, Planets and much more... 2007-03-08 11:00:00 Seminar Link You Tube abstract
CODEX, a high resolution, super-stable spectrograph to be fed with the E-ELT, the most powerful telescope ever conceived, will for the first time provide the possibility of directly measuring the change of the expansion rate of the Universe with time and much more, from the variability of fundamental constants to the search for other earths. A study for the implementation at the VLT of a precursor of CODEX, dubbed ESPRESSO, is presently carried out by a collaboration including ESO, IAC, INAF, IoA Cambridge and Observatoire de Geneve.
Mario Gai INAF - Osservatorio Astronomico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Aldo Dell'Oro An efficient PSF construction method. 2007-02-01 11:00:00 Seminar Link You Tube abstract
Image computation is a fundamental tool for performance assessment of astronomical instrumentation, usually implemented by Fourier transform techniques to derive the diffraction limited imaging performance. We review the numerical implementation, evaluating a direct implementation of the discrete Fourier transform (DFT) algorithm, compared with usual fast Fourier transform (FFT) tools. Simulations show that the precision is quite comparable, but in the case investigated the computing performance is considerably higher for DFT than FFT. The application to image simulation for the mission Gaia and for Extremely Large Telescopes is discussed.
Roberto Mignani Mullard Space Science Laboratory, University College London Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alessandro Spagna Astrometry, proper motions and photometry of planetary nebulae with the GSC-II. 2006-12-22 11:00:00 Seminar Link You Tube abstract
Originally conceived as a support for telescope operations (HST, XMM, VLT, JWST) , the Guide Star Catalogue II gas has soon unveiled its enormous potentialities for many science applications. As one of the many examples, in this talk, I will present the first very comprehensive study (astrometry, kinematics, interactions with the ISM, morphology, photometry) of the whole Planetary nebulae population, carried out with the Guide Star Catalogue II, as well with other public catalogues and data from public imaging surveys.
Alberto Riva gOlem, INAF OaBr-Merate Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Deborah Busonero IRAIT-AMICA, Infrared astronomy in Antarctica. 2006-12-06 11:00:00 Seminar Link You Tube abstract
AMICA (Antarctic Multiband Infrared CAmera) is an instrument designed to perform astronomical imaging from Dome-C in the near- (1^5 micron) and mid- (5^27 micron) infrared wavelength regions. AMICA will be mounted at the Nasmyth focus of the 80 cm IRAIT telescope and will perform survey-mode automatic observations of selected regions of the Southern sky. The first goal will be a direct estimate of the observational quality of this new highly promising site for Infrared Astronomy. In addition, IRAIT, equipped with AMICA, is expected to provide a significant improvement in the knowledge of fundamental astrophysical processes, such as the late stages of stellar evolution (especially AGB and post-AGB stars) and the star formation.
Massimo Capaccioli INAF - Osservatorio Astronomico di Capodimonte Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available The VLT Survey Telescope: a wide-field scientific opportunity 2006-10-27 11:00:00 Seminar Link You Tube abstract
The VLT Survey Telescope (=VST) is a 2.6 m aperture, new-technology wide-field imager equipped with a 16kx16k optical camera matching a 1°x1° field (scale 1 px =0"2). It will operate from the ESO Observatory at Cerro Paranal, Chile. The VST project is a joint venture among ESO (responsible for coordination, civil work and on-site operations), the Capodimonte Observatory-OAC at Naples (telescope), and the European consortium Omegacam (camera). By MoU, in return for the procurement of the telescope OAC shall receive from ESO (running VST) an amount of guaranteed observing time (GTO) with VST of the order of 20% of the total. For the reduction, analysis, archiving, and scientific exploitation of the VST material from GTO and from Italian participation to ESO public surveys (such as KIDS and ATLAS), INAF has created an ad hoc center at Naples (VSTceN). The talk is about the characteristics of the instrument (telescope, optics, camera, civil works), the status of the project (hardware and software), the schedule of the activities up to the first light/operation, expected in the second half of 2007. The key point, though, is the illustration of the OAC GTO survey projects (spanning from the Solar System to cosmology, and including participations to ESO public surveys). So far these projects have been elaborated mostly by OAC people, but they are fully open to collaborations.
Erez Ribak Technion - Israel Institute of Technology, Department of Physics Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Mario Gai Searching for temporal coherence in astrophysics 2006-10-15 11:00:00 Seminar Link You Tube abstract
It is proposed to probe the temporal coherence of celestial objects to locate natural coherent sources, such as masers. But we might also see gravitationally lensed objects, ionospheres of planets, and occasionally intelligent life forms that use lasers. A simple realisation is by an imaging interferometer operating at large optical path difference, and is rather easy on a single telescope with a zero-shear interferometer. In a survey mode, a very wide field is measured, yielding all the coherent sources in it. Past experience shows that coherent signals can be detected against their incoherent bright host objects. The contrast ratio demonstrated is one thousand, and at known wave length, more than a million.
Vincenzo Zappalà INAF - Osservatorio Astronomico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available Bye bye Pluto, welcome 134340! 2006-09-28 11:00:00 Seminar Link You Tube abstract
Il seminario avrà come oggetto la storia della scoperta e del declassamento di Plutone, nonché della nuova definizione di pianeta, con i suoi pregi ed i suoi difetti.
Marco Pignatari Università di Torino, Dipartimento di Fisica Generale Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Aldo Dell'Oro Xe e Kr nei granuli presolari mainstream SiC: confronto con i modelli di stelle AGB 2006-07-06 11:00:00 Seminar Link You Tube abstract
Diverse osservazioni e misure isotopiche indicano che i granuli di origine presolare di tipo mainstream SiC provengono dalle stelle AGB di piccola massa (1.5-3 masse solari). Tali granuli mostrano un chiaro segno del processo s (o cattura neutronica lenta) avvenuto nelle stelle di origine, e la loro analisi isotopica fornisce un'occasione unica di confronto con le predizioni teoriche da parte dei modelli di stelle AGB. Questo seminario riguardera' in particolare i gas nobili Kr e Xe, i cui rapporti isotopici sono stati misurati su campioni di milioni di granuli e mostrano una chiara componente da processo s. Partendo dalle osservazioni verranno discussi i possibili scenari in cui i mainstream SiC sono stati arricchiti di tale componente, sempre utilizzando le informazioni che vengono dai modelli di stelle AGB.
Don Lamb University of Chicago (USA) Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available Discovery of a new mechanism for type Ia supernovae 2006-06-13 11:00:00 Seminar Link You Tube abstract
Type Ia supernovae (SNe) are important because of their contributions to the abundance of heavy elements and their use as cosmic "yardsticks" to measure the rate of expansion of the universe, and therefore to determine the properties of dark energy. Yet the mechanism by which these supernova explosions occur is not known. In this talk, I first give a brief overview of the chronology of a Type Ia supernova and the key physics involved in each stage. I argue that neither nuclear burning via an ordinary flame (a "deflagration wave") or by a strong shock (a "detonation" wave) can produce the properties that we observe for most Type Ia SNe, while a deflagration phase followed by a detonation phase can do so. I then describe current state-of-the art numerical simulations of Type Ia SNe, focusing on the discovery of a new mechanism for Type Ia SNe, which we have termed "gravitationally confined detonation." This discovery illustrates the importance of large-scale, multi-physics simulations as a tool for discovery, particularly in the case of non-linear astrophysical phenomena. Finally, I discuss the possible implications of this discovery for the use of Type Ia SNe as "standard candles" for measuring expansion rate of the universe, and therefore determining the properties of dark energy.
Nicolò Antonietti Politecnico di Torino, Dipartimento di Ingegneria delle Telecomunicazioni Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available La Relatività e la Meccanica Quantistica per le Comunicazioni Spaziali e lo Studio del Sole 2006-05-04 11:00:00 Seminar Link You Tube abstract
Le due più grandi conquiste della fisica del Novecento sono la Teoria della Relatività e la Meccanica Quantistica. Pur essendo state entrambe studiate ad un consistente livello di profondità, da quasi un secolo, solo da pochi anni si indagano le applicazioni che da esse nascono nel campo delle Comunicazioni Spaziali. Secondo la Relatività Generale, le onde elettromagnetiche che si muovono in prossimità di enormi concentrazioni di massa subiscono una deflessione dal cammino rettilineo: è l'effetto di lente gravitazionale. Nel contempo, questa deflessione genera un guadagno di potenza che può essere sfruttato per aumentare la capacità di trasmissione o di ricezione di un'antenna. Per il Sole, ad esempio, il fuoco della lente gravitazionale inizia (in tutte le direzioni radiali partendo dal Sole) a circa 550 Unita` Astronomiche, ovvero a 3,17 giorni luce di distanza, e questa è una distanza considerevole in quanto è ben oltre 14 volte la distanza di Plutone. Questo fenomeno avviene in quanto le onde elettromagnetiche non riescono passare dentro al Sole. Le onde gravitazionali, invece, dovrebbero poter passare dentro al Sole senza disturbo, e quindi il loro fuoco verrebbe a trovarsi fra Urano e Nettuno. Il guadagno e il comportamento della lente gravitazionale dipendono fortemente dalla struttura della stella e della sua atmosfera. Un'inversione del processo, data la conoscenza del comportamento della lente, porterebbe ad una comprensione maggiore della struttura della stella. Dall'altra parte, le proprietà della Meccanica Quantistica assicurano un processo di comunicazione matematicamente sicuro. Numerosi gruppi di ricerca stanno studiando quanto queste proprietà si mantengano valide a distanze spaziali per poter garantire sicure comunicazioni spaziali. In particolare è in corso un progetto per studiare come un fotone che attraversa l'atmosfera vada incontro a decoerenza e rottura di entanglement. Un simile studio per un fotone che attraversa la corona di una stella, potrebbe dare informazioni riguardanti la composizione della stella e della sua corona. In questo seminario si presentano le problematiche descritte ed i possibili sviluppi sperimentali e teorici che hanno condotto il relatore a sciegliere questi argomenti per la sua Tesi di Dottorato in Scienza delle Telecomunicazioni al Politecnico di Torino.
Hakki Ogelman University of Wisconsin (USA) Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available The End of Oil 2006-01-26 11:00:00 Seminar Link You Tube abstract
Oggetto del seminario è il problema dell'approssimarsi della fine delle risorse petrolifere e dell'urgenza di individuare fonti energetiche alternative.
Paola Re Fiorentin Max Planck Institut fur Astronomie, Heidelberg Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Alessandro Spagna Detection of fossil structures in the Galactic halo by means of spectro-photometric and proper motion surveys 2006-01-05 11:00:00 Seminar Link You Tube abstract
Not Available.
John Gallagher University of Madison (USA) Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available Starbursts and Super Star Clusters 2005-12-06 11:00:00 Seminar Link You Tube abstract
Observations with the Hubble Space Telescope make it clear that star formation processes in starburst galaxies are not simply scaled up versions of what we observe in normal galactic disks. Instead of OB associations, many massive stars form in compact, massive super star clusters (M~10^5-10^6 Msun, half light radii < 5 pc) which in turn form the skeletons of starburst clumps. Using a few nearby galaxies as examples, I will summarize the properties of super star clusters and then briefly review issues relating to their evolution and impact on the host galaxies.
Alessandro Drago INFN - Sezione di Ferrara Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available GRBs and quark deconfinement in compact stars 2005-10-28 11:00:00 Seminar Link You Tube abstract
I will present a model in which long GRBs are originated by the transition from a purely hadronic star to a star made, at least in part, of deconfined quark matter. I will discuss the possible signatures of the model, namely a) the possible existence of two compact stars having similar masses but rather different radii; b) the possible time-delay between the SN explosion and the GRB, with the SN preceding the GRB; c) the possibility of explaining GRBs in which active periods are separated by quiescent times lasting sometimes hundreds of seconds.
Mariko Kato Keio University (Yokohama, Japan) Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available Universal decline law of classical nova and light curve analysis of multi-wavelength observation 2005-09-15 11:00:00 Seminar Link You Tube abstract
This talk concern light curve fitting of classical novae using optically thick wind theory. X ray turn on/off time is shown for various white dwarf mass and the chemical composition. These time scales give a mass estimate for GQ Mus and V1974 Cyg. A universal decline law, recently proposed by Hachisu and Kato, explains the decline rate of optical and infrared fluxes due to free-free emission: I will show a large number of examples of light curve fitting with multi-wavelength bands for classical novae. A detaild analysis of V1974 Cyg light curve consists of X-ray, UV and visual band fittings. I will also introduce light curve modeling of super-Eddington phase of V1974 Cyg.
Edward Tedesco University of New Hampshire (USA) Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available The Size-Frequency Distribution for Main-Belt Asteroids 2005-09-14 11:00:00 Seminar Link You Tube abstract
I will summarize the creation of a model of the main asteroid belt whose purpose is to describe the population's size frequency distribution and allow simulation of their numbers and fluxes at visual through mid-infrared (~0.3 - 70 micrometers) wavelengths in any area of sky for an arbitrary date (Tedesco, Cellino, and Zappala, 2005, Astron. J. 129, pp. 2869-2886). This model is based on a population of ~1.9x10^6 asteroids obtained from the complete known asteroid sample, plus extrapolation of the size-frequency distributions of 15 asteroid dynamical families and three background populations, to a diameter limit of 1 km. Because reliable diameters are available for very few small asteroids (D < ~25 km) all SFDs must estimate the diameters of smaller asteroids from their measured visual (Johnson V-band) absolute magnitudes (H) and an adopted visual geometric albedo (pV). In fact, most measured albedos depend upon knowledge of H. Thus, the discovery, last month, that there exists a significant systematic error in H, rather than simply a zero-point offset, (at least over the range of 12.5 to 15.5) has serious implications for determination of the main-belt asteroid size-frequency distribution. At this seminar I will present the evidence for this conclusion and its implications.
Mario Gai INAF - Osservatorio Astronomico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available Chromaticity in Gaia 2005-06-30 11:00:00 Seminar Link You Tube abstract
Chromatic effects are usually associated with refractive optics, and reflective telescopes are assumed to be free from them. We show that all-reflective optics, free from chromatic aberration, still bears significant levels of chromaticity, in terms of photo-centre displacement depending on source spectral type. The effect is critical to modern micro-arcsecond astrometric experiments like Gaia. We analyze the diffraction image formation and measurement process, to derive a precise definition of the chromatic variation of the image position, and we evaluate the key aspects of optical design with respect to chromaticity. The fundamental requirement related to chromaticity is the symmetry of the optical design and of the wavefront errors. We address some optical engineering issues, as manufacturing and alignment, providing recommendations to minimize the degradation that chromaticity introduces on astrometry. The effect of specific aberrations on the diffraction image can be quantified in terms of shape description parameters like moments. We evaluate the relation among moments and chromaticity, proposing a tool based on a neural network for diagnostics on the science data, and removal in data processing, of the chromatic error. In a simple framework, the RMS chromaticity on a random set of aberrated images is reduced from 1.6 mas to 6 micro-arcseconds, proving the effectiveness of the proposed technique.
Alan Gabriel Institut d'Astrophysique Spatiale, Orsay - Paris Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available Recent observations of the onset region of the fast solar wind 2005-04-28 11:00:00 Seminar Link You Tube abstract
The structure of the fast solar wind in the interplanetary medium is dominated by the geometry of the large-scale coronal magnetic field. For this we have no solid measurements, but can deduce many parameters from other observations and theoretical ideas. Our observations by remote optical sensing of the wind itself lead to a picture of the early acceleration of the wind on a variety of spatial scales. It is now widely believed that the acceleration and the heating of the corona are closely related processes.
Gustavo Yepes Universidad Autonoma de Madrid Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available Cosmological simulations of galaxy formation in different density environments: from voids to clusters 2005-02-11 11:00:00 Seminar Link You Tube abstract
Not Available.
Gehrard Ortwin Astronomisches Institut der Universität Basel, Switzerland Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available Structure and mass distribution of the Milky Way 2004-12-21 11:30:00 Seminar Link You Tube abstract
This talk summarizes the large-scale structure of our barred Milky Way Galaxy and the known constraints on the distribution of baryonic and total mass. The structural parameters of the bulge and disk are discussed along with their uncertainties, and some dynamical effects in the local disk are described which may well be caused by the Galactic bar. Finally, the Milky Way's mass distribution is discussed in the light of current predictions from LCDM cosmology.
Luciano Periale Istituto di Fisica dello Spazio Interplanetario, Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available New concepts in Astroparticle Deterctors for WIMPs searcing 2004-12-01 11:30:00 Seminar Link You Tube abstract
Some experimental results on direct WIMPs searching are presented. A different detecting technique for charged and neutral particles with the most sofisticated and promising background rejection method are evidenced. A new concepts on a coherence photo-detector to better underline the neutral particles detecting are discussed.
Angela Slavova Institute of Mathematics and Informatics - Bulgarian Academy of Sciences, Sofia, Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Mario Gai Cellular Neural Networks and Applications 2004-11-09 10:30:00 Seminar Link You Tube abstract
Many complex computational problems can be formulated as well-definedtasks where the signal values are placed on a regular geometric 2-D or 3-D grid, and the direct interactions between signal values are limited within a finite local neighborhood. CNN is an analog dynamic processor array which reflects just this property: the processing elements interact directly within a finite local neighborhood. Cellular Neural Networks have very impressive and promising applications in image processing and pattern recognition. For such applications CNN functions as a two-dimensional filter. However, unlike the conventional two-dimensional digital filters, our cellular neural network uses parallel processing of the input image space and delivers its output in continuous time. This remarkable feature makes it possible to process a large-size image in real time.
Fernando de Felice Dipartimento di Fisica "G.Galilei", Università di Padova Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available Gamma ray burst e macchine del tempo cosmiche 2004-10-26 14:30:00 Seminar Link You Tube abstract
Not Available.
Marco Delbo' INAF - Osservatorio Astronomico di Torino Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available The nature of Near-Earth Asteroids from the study of their thermal infrared emission 2004-10-14 10:30:00 Seminar Link You Tube abstract
I present the principles and the application of asteroid thermal models to derive sizes and albedos of near-Earth Asteroids (NEAs). I describe recent results of thermal infrared observations obtained with the Keck1, the ESO3.6m and the NASA-IRTF telescopes. The findings increase the number of NEAs having measured albedos by more than 35%. The mean albedo of our sample is higher than previous estimations, suggesting that these asteroids are on average smaller than previously thought. Applying this result to the known 2.200 NEAs, we revise down the likelihood of a massive asteroid to hit the Earth by 20-30%. NEAs do not only have higher albedos than larger main-belt asteroids, but they differ also in surface thermal properties. We have derived for the first time a best-fit estimate for the thermal inertia of the observed NEAs. Our result put constraints on the strength of the Yarkovsky effect on kilometer and sub-kilometer size bodies.
Li Chen Shanghai Astronomical Observatory, Chinese Academy of Sciences Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available China Recent developments on the Galactic disk abundance gradients. 2004-10-11 14:30:00 Seminar Link You Tube abstract
With updated open cluster data we derived a radial iron gradient which is quite consistent with the most recent determination of oxygen gradient by nebulae and young stars. By dividing clusters into age groups, we show that iron gradient was steeper in the past. Based on our cluster sample, no significant evidence was found for the existence of AMR in the Galactic disk. Some recent developments on metallicity gradients from OB stars are also discussed.
Ewald Mueller Max-Planck Institute fur Astrophysik, Monaco, Germania. Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Not Available Cosmic Catastrophies: Core Collapse Supernovae. 2004-09-27 10:00:00 Seminar Link You Tube abstract
At the end of their thermonuclear evolution, massive stars with more than about ten times the mass of our Sun develop a core composed of mostly iron group nuclei which becomes dynamically unstable against gravitational collapse. This iron core collapses to a neutron star or a black hole releasing its large gravitational binding energy which is sufficient to power a core collapse supernova explosion of the star. Due to the very high densities encountered during core collapse neutrinos are created in huge numbers by inverse beta-decay (neutronisation of the core). The neutrinos eventually escape from the dense neutron star, but before leaving the stellar interior they deposit some of their energy in the still infalling outer layers of the star. According to the commonly accepted paradigm this neutrino heating is believed to cause the violent disruption of the star in a supernova explosion. The neutrino heating process also seeds non-radial flow instabilities which in turn trigger Rayleigh-Taylor instabilities causing large scale mixing in the expanding stellar envelope. Simulating such events poses a major computational challenge for several reasons which will be addressed in my talk. The problem involves vastly different length scales and time scales comprising many orders of magnitude, the hydrodynamic flow is of genuine multi-dimensional nature, and a detailed treatment of the transport of neutrinos is required. The latter requires the solution of a multi-dimensional Boltzmann equation for different neutrino flavors taking into account phase space blocking effects due to their fermionic nature. In addition, effects due to relativistic gravity and explosive nuclear burning have to be incorporated into the simulation program.
Antonino Del Popolo Bogazici University, Physics Department, Istanbul Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Mario Lattanzi Turkiye Analytical dynamical models of galaxy clusters: improvement of the Luminosity-Temperature relationship and constraints on cosmological parameters. 2004-09-16 11:00:00 Seminar Link You Tube abstract
Erez Ribak Technion - Israel Institute of Technology, Department of Physics Osservatorio Astronomico di Torino, sala seminari di Villa Magliola Mario Gai Adaptive optics and multiple beam interferometry 2004-08-05 11:00:00 Seminar Link You Tube abstract
With the advent of infra-red imaging by adaptive optics, it should also be easier to improve visible imaging, by using interferometry. Different realizations of interferometers will be proposed. In addition, it is proposed to improve visible interferometry (after adaptive optics or between independent telescopes) by combining many beams simultaneously as in radio astronomy.