Pulsation and Mass Loss of AGB Stars in the Magellanic Cloud Clusters NGC 1978 and NGC 419

摘要

We present results of a study of asymptotic giant branch (AGB) stars in the Magellanic Cloud clusters NGC 1978 and NGC 419. The aim of this work is to use pulsation analysis as a means to study mass-loss on the AGB. We derive pulsation masses for the AGB variables, from the lowest luminosity O-rich variables to the most evolved infrared sources. Our studies show that reliable pulsation masses can be determined for AGB stars. We also use non-linear pulsation models to fit the highly evolved AGB stars. Our models show that a substantial amount of mass loss has occurred during the AGB evolution of these stars. We compare our results to commonly-used mass-loss formulae such as those of Vassiliadis & Wood (1993) and Bl?cker (1995).