Mass Loss from Low- and Intermediate-mass Stars

Abstract

Low‐ and intermediate‐mass single stars (LIMS) have initial masses M<∼6−7 M⊙. They end up as white dwarfs of ∼0.6−1.4 M⊙, the rest of their mass being lost during their nuclear‐burning lifetimes. Stellar pulsation theory can be used to estimate current (as opposed to initial) stellar masses and can be used to trace accumulated mass loss when the initial mass is known. Some examples are given for RR Lyrae stars, first giant branch (FGB) and asymptotic giant branch (AGB) stars, and Cepheid variables. Most of the mass loss from LIMS is thought to occur on the FGB and AGB, although it has been argued that pulsation masses derived for Cepheids suggest that there is significant mass loss in earlier evolutionary phases. Direct estimates of mass loss rates can also be used to estimate the amounts of mass lost from LIMS. Some recent Spitzer‐based estimates of mass loss rates for AGB stars in the Magellanic Clouds are discussed. Finally, binary and variable AGB stars that may be related to asymmetic mass loss such as that seen in elliptical and bipolar planetary nebulae are discussed.