Back to Volume
Paper: Of Photons, Gas, and Dust: The Mira Mixmaster
Volume: 412, The Biggest, Baddest, Coolest Stars
Page: 163
Authors: Luttermoser, D.G.
Abstract: The physical processes in the atmospheres of asymptotic giant branch (AGB) stars have many important attributes. Their large mass-loss rates impact their evolution and enrich the metal content in the Galaxy. Virtually all AGB stars vary in brightness, which includes the Mira-type variables. The Mira brightness variability is caused by pulsations which produce a ‘shocked’ atmosphere. Excitation and ionization collisional rates are small in comparison to radiative rates, due to the low densities, which makes the LTE approximation invalid. The cool atmospheric temperatures of these stars allow molecules and dust to form which further complicates the picture – the formation of these species may not be in equilibrium either. Atmospheric modeling of these stars has followed two different approaches: (1) the hydrostatic (HS) method and (2) the hydrodynamic (HD) method. Each of these techniques has its limitations. Dust is often seen in these stars and dust formation is an important component to the chemistry of these atmospheres and to the mass loss. This paper will highlight what has been done to date in modeling the atmospheres of these stars and make suggestions as to what should be done in future modeling attempts.
Back to Volume