Astrolunch: Marica Valentini

Tue, 01/02/202212:30-13:30
Title: Ages of metal-poor stars: a synergy between asteroseismology and high-resolution spectroscopy.
Abstract: Metal poor stars are key to understand the history of our Galaxy. In their element abundances pattern and kinematics is encoded their origin, and when the stellar age is available, we obtain paramount hints on the chemical enrichment and evolution history of the Milky Way. However, to obtain precise ages for field metal poor stars is a challenging task: at present only a handful very metal-poor stars have ages, derived by using nucleo-cosmo-chronology (via Thorium and Uranium abundances). Asteroseismology in recent years demonstrated to be a powerful tool to derive masses, and hence ages, of red giant stars. When this technique is applied to metal poor stars, it is possible to increase the number of metal poor stars with an precise age measurement. For this purpose in 2018 we started a project combining asteroseismology and UVES high resolution spectroscopy for about 200 metal-poor halo giants ([Fe/H]<-1.5 dex). Targets are identified in RAVE and APOGEE surveys. We obtained seismic information from the light curves collected by the Kepler, K2, and TESS space missions, detailed chemical abundances, from ESO-UVES and HARPS-N high resolution spectra, kinematics from Gaia database. The final atmospheric parameters and abundances, together with the seismic information and Gaia data, are used for infer stellar masses, radii and ages, via Bayesian fitting on a set of isochrones. Following the method we developed in our pilot study, Valentini et al. (2019), we present here a sample of ~40 metal poor stars (the first UVES campaign of our program) for which we determined precise ages, chemistry and kinematics. For the first time a consistent and rigorous approach have been established, where the synergy between spectroscopy, kinematics and asteroseismology is used for better understanding the Milky Way Halo.