Mass Loss in the Metal-Poor Regime: Asteroseismic Masses of Red Giants in Globular Cluster NGC 5897

Stellar mass is one of the most fundamental parameters of stars and it plays a key role in shaping evolutionary pathways. While precise mass measurements are available for binary systems, the determination of stellar masses beyond these systems mainly relies on asteroseismology of main-sequence, subgiant, and red giant stars. As stars evolve, they undergo mass loss, which significantly affects their further evolution and is thus a critical component of stellar models. However, for low-mass stars, mass loss remains poorly understood and lacks a comprehensive theoretical framework. Simple recipes such as the Reimers (1975) scheme are usually applied, even though they seem inconsistent with observations, suggesting more complex and diverse processes. Measuring integrated mass loss between evolutionary phases such as the red giant branch (RGB) and the asymptotic giant branch (AGB) is challenging, as the similar pulsational characteristics of these phases complicate their identification based solely on asteroseismic data. Mono-age, mono-metallicity samples, such as globular clusters, provide a unique opportunity to compare these masses directly to infer mass loss. In this talk, we present newly derived constraints on the integrated mass loss between the RGB and Early-AGB phases in the most metal-poor Kepler K2 globular cluster, NGC 5897. This extends the current metallicity–mass-loss relation for K2 globular clusters into the very metal-poor regime. We also compare our results with other metallicity–mass-loss relations for different metallicity regimes and shed some light on how RR Lyrae stars can play a role in future investigations.