Giovedì 10 Ottobre 2019, ore 11:00

Osservatorio Astrofisico di Torino, Sala Seminari di Villa Magliola

A Low-mass Planet Candidate Orbiting Proxima Centauri at a Distance of 1.5 AU

Dr. Mario Damasso



By analyzing ~17 years of radial velocity data of Proxima Cen collected with the UVES and HARPS spectrographs, we detected a signal of period P~5 years that could be explained by the presence of a second planet, Proxima c, with minimum mass m sin i~6. Earth masses. Together with the low-mass temperate planet Proxima b, this candidate planet would make Proxima the closest multi-planet system to the Sun. I will present the properties of the new RV signal and investigate the likelihood that it is related to a magnetic activity cycle of the star. I will discuss how the existence of Proxima c can be confirmed, and its true mass determined with high accuracy, by combining Gaia astrometry and radial velocities. Proxima c would be a prime target for follow-up and characterization measurements, especially with next generation direct imaging instrumentation due to the large maximum angular separation of ∼1 arcsecond from the parent star. Since the orbit would be beyond the original location of the snowline, Proxima c would challenge the models of the formation of super-Earths.