Giovedì 23 Maggio 2019, ore 11:00

Osservatorio Astrofisico di Torino, Sala Seminari di Villa Magliola

Dissecting the young Galaxy via NIR spectroscopy of Cepheids

Dr. Laura Inno

INAF – Osservatorio Astrofisico di Arcetri


Besides being the most accurate stellar distance indicators, young Cepheids are arguably the best stellar proxy for the detailed chemical composition of the ISM in the Milky Way: they are young (20-250 Myr); age-datable by their periods; luminous and hence visible to large distances; and their surface temperatures (~5,000K) allow precise abundance determinations of many different chemical elements. However, such abundance maps are limited by the small number of Cepheids known in the most reddened regions of the Galactic disk. These limitations are currently being overcoming by on-going deep optical and near-infrared (NIR) variability surveys, such as Gaia, VVV, IRSF and PS1, which are capable of cope with the thorny problems of the high extinction and of differential reddening. Similarly, only NIR spectrographs allow us to collect spectra with reasonable Signal-to-Noise ratio to determine the chemical abundances of such obscured stars. But near-infrared spectroscopy of Cepheids is still in its infancy and there is no background study available in the literature. I will present the first chemical abundance ever estimated from NIR low resolution spectra of five new Cepheids discovered in the inner edge of the Galactic disk, together with the pioneering work I am carrying out by using NIR high resolution spectrographs, such as CARMENES (R~90,0000), GIANO (R~50,0000) and APOGEE (R~22000) to allow the determination of stellar parameters, kinematics and chemical abundances of Cepheids from single-epoch observations.