Stellar OH masers with polarized features at intermediate velocities.
Abstract
Peculiar profiles were discovered in EY And, one of five new sources found in an OH maser search. The 1612-MHz emission has a typical, double-peak structure, but the main-line masers show polarized features at the central velocity of the 1612-MHz emission. The line shape of the SiO maser resembles that of the 1665-MHz emission. Maser sources with polarized OH emission at intermediate velocities are discussed in the context of two kinematic models. Expanding envelopes with a smooth velocity field would require some of the polarized OH features to arise in the innermost part of the envelopes. Distortion of a smooth outflow by interaction with the ambient gas cannot explain the peculiar OH emission. It is interpreted as a fluctuation of the velocity field of the expanding envelope. The polarized features in both main-line spectra have the same sense of circular polarization when they appear at nearly the same velocity. This evidence is consistent with the mechanism proposed by Cook and Shklovskii.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- September 1984
- Bibcode:
- 1984A&A...138..343U
- Keywords:
-
- Hydroxyl Emission;
- Interstellar Masers;
- Late Stars;
- Polarization Characteristics;
- Radial Velocity;
- Stellar Spectrophotometry;
- Astronomical Models;
- Circular Polarization;
- M Stars;
- Stellar Magnetic Fields;
- Stellar Mass Ejection;
- Variable Stars;
- Astrophysics