A wall of dust around a proto-Mira
Albert A. Zijlstra. Ronald Weinberger, 2002, ApJ, 572, 1006
Abstract
We present the discovery of a huge (19' by 16') dust ring surrounding
a bright (V = 10.60) red star. The dust ring has, at D = 700 pc, a
diameter of 4 pc, and a central hole of 1.5 pc across. Part of
the shell is also seen as an absorption nebulosity. The star is
classified as a M3III AGB star. Among AGB stars its detached shell is
of unrivalled size. Detached shells around AGB stars are normally
interpreted in terms of thermal pulses. However, in this case a
significant fraction of the shell may consist of swept-up ISM; the
detached appearance can be explained with wind--ISM interaction. We
present a model where the AGB wind has been stopped by the surrounding
ISM, and the swept-up shell is now expanding at the sound speed. The
model predicts that the ring will disperse over a few times
105yr, and eventually will leave a large hole in the ISM
surrounding the AGB star or its future planetary nebula.
paper (pdf, 150kb)