RGB mass loss: inferences from CMD-fitting and asteroseismology
Marco Tailo (Unibo)
Tuesday 30/11/2021 @ 14:00, Sala IV piano Battiferro
The amount of mass lost by stars during the red-giant branch (RGB) phase is one of the main parameters needed to fully understand later stages of stellar evolution and, when the mass of such stars is evaluated trough asteroseismology, correctly evaluate their age. In spite of its importance, a fully-comprehensive physical understanding of this phenomenon is still missing, and we, mostly, rely on empirical formulations. The Globular Clusters are ideal targets to derive such formulations, but, until recently, the presence of multiple populations has been a major challenge in constraining both stellar mass and RGB mass loss. In this talk, I will discuss the insights on RGB mass loss that can be obtained from the study of the horizontal branch stars in such stellar associations. The estimates obtained via the study of the photometric data will be compared with recent and newly obtained mass and mass loss estimates derived for few GCs with asteroseismic techniques, specifically M4. Furthermore, I will discuss results on high metallicity clusters and stars that allow to extend the metallicity range of past studies to solar and supersolar values. Finally, it will be explained how the integrated RGB mass loss, once accurately measured, show precise trends that are difficult to describe with standard models. The implications relevant for the field of stellar evolution are also discussed, as our findings suggest the existence of a universal mass loss law for RGB stars.