Shocks in the Radio Photospheres of Long Period Variable Stars

Abstract

At a distance of a few stellar radii and beyond from the center of a Mira variable, dust condenses (see Danchi et al. 1994) and mass begins to stream away from the star as a result of radiation pressure on the dust and subsequent drag on molecules. Since a significant fraction of the mass returned to the interstellar medium comes from red giant stars, this is an important process which affects star formation and galaxy evolution. However, fundamental questions still remain relating to the movement of mass outwards to a few stellar radii and the conditions under which dust forms. Thus, new approaches to study the region between the optical photosphere and the dust formation zone are extremely valuable.