Reflection Nebulae Around Red Supergiants
Abstract
The possibility is considered of detecting, from its polarization, continuum light scattered by circumstellar dust grains around red giants in regions well away from the central star. An expression for the intensity of such scattered light is obtained using a model of a reflection nebula undergoing spherically symmetric expansion about a central star with constant mass-loss rate and outward flow velocity. It is assumed that the grains scatter isotropically and that the optical depth through the nebula is small. Applying the analysis to a possible reflection nebulosity around the red supergiant Alpha Ori and taking account of scattering by earth's atmosphere, it is concluded that the apparent halo around this star may be as much as 6% positively polarized at a distance of 15 arcsec from the star and that the percentage polarization should decrease linearly with increasing distance away from the star.
- Publication:
-
Astrophysical Letters
- Pub Date:
- 1976
- Bibcode:
- 1976ApL....18....5J
- Keywords:
-
- Nebulae;
- Polarized Light;
- Red Giant Stars;
- Stellar Envelopes;
- Supergiant Stars;
- Light Scattering;
- Stellar Mass Ejection;
- Astrophysics