Circumstellar envelope structure of late-type stars.
Abstract
The arcsecond structure of OH maser clouds surrounding 20 Mira variables and late-type supergiants has been measured using the VLA in a spectral line mode at 1612 MHz. Angular radii of the maser clouds range from <0arcsec.5 to 4arcsec and have been combined with phase lag measurements of the shell size to estimate distances for some of the stars. The outer radii range from 100 AU to 104AU, and the authors estimate a ratio of outer to inner radii ⪉4 for the maser regions. The previously discovered correlation between the mass loss rate and the outer radius of the maser region is confirmed and used to determine the mass loss rates for eight stars. The results of this work are compared with current theoretical models of circumstellar shells and the implications for mass loss mechanisms and the evolutionary fate of these stars are considered. It is suggested that the rare cases of nonspherical shells are indicating the presence of close binary companions.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1983
- DOI:
- 10.1086/161485
- Bibcode:
- 1983ApJ...274..733B
- Keywords:
-
- Interstellar Masers;
- Late Stars;
- Stellar Envelopes;
- Stellar Mass Ejection;
- Variable Stars;
- Astronomical Maps;
- Density Distribution;
- Interferometry;
- Mira Variables;
- Position (Location);
- Radial Velocity;
- Radii;
- Supergiant Stars;
- Astrophysics