Asteroseismology of Metal-poor Red Giants Observed by TESS

Abstract

Galactic archeology has long been limited by a lack of precise masses and ages for metal-poor stars in the Milky Way’s thick disk. However, with TESS providing a growing number of photometric observations, it is possible to calculate masses and ages for more solar-like oscillators than ever using asteroseismology. We have used the pySYD pipeline to determine global asteroseismic parameters, and calculated the masses and ages of 506 metal-poor ([M/H] < −0.5) red giants observed by TESS. Our findings appear to show metallicity-dependent mass loss on the upper red giant branch and identify a set of “young” high- α stars that have been detected in other studies. We also find that 32.6% of the metal-poor stars appear to be binary interaction products, and four stars with stellar ages that could be from the Gaia-Enceladus/Sausage system. In combination with existing ages from Kepler/K2, these data can be compared to galactic evolution models to better determine the formation history of the Galaxy.