Polarisation by Thomson scattering in optically thin stellar envelopes. II. Binary and multiple star envelopes and the determination of binary inclinations.
Abstract
A general expression is derived for the linear polarization (i.e., the Stokes parameters) arising from scattering in any optically thin envelope illuminated by any number of unpolarized point sources. The result is applied to a binary system with a circular orbit and a corotating (but otherwise arbitrary) envelope. Methods of diagnosing the geometric properties of the envelope from the observed Stokes parameters are described, and consequences of both finite star size and a lack of corotation are considered. The method outlined is used to analyze published data on the binary systems AO Cas, Sigma Ori E, and Cyg X-1. It is shown that the polarization variations of AO Cas and Sigma Ori E are reasonably consistent with scattering in optically thin circumstellar material, while those of Cyg X-1 yield contradictory results for the system's orbital inclination.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 1978
- Bibcode:
- 1978A&A....68..415B
- Keywords:
-
- Binary Stars;
- Optical Thickness;
- Polarized Electromagnetic Radiation;
- Stellar Envelopes;
- Thomson Scattering;
- Attitude (Inclination);
- Electron Scattering;
- Linear Polarization;
- Stokes Law Of Radiation;
- Astrophysics;
- Binaries:Envelopes;
- Envelopes:Multiple Stars;
- Polarization:Stellar Envelopes;
- Scattering:Stellar Envelopes