Be-star rotation: how close to critical?
Abstract
We argue that, in general, observational studies of Be-star rotation have paid insufficient attention to the effects of equatorial gravity darkening. We present new line-profile calculations that emphasize the insensitivity of line width to rotation for fast rotators. Coupled with a critical review of observational procedures, these calculations suggest that the observational parameter v sini may systematically underestimate the true projected equatorial rotation velocity, ve sini, by some tens of per cent for rapid rotators. A crucial implication of this work is that Be stars may be rotating much closer to their critical velocities than is generally supposed, bringing a range of new processes into contention for the elusive physical mechanism responsible for the circumstellar disc thought to be central to the Be phenomenon.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- May 2004
- DOI:
- 10.1111/j.1365-2966.2004.07627.x
- arXiv:
- arXiv:astro-ph/0312113
- Bibcode:
- 2004MNRAS.350..189T
- Keywords:
-
- line: profiles;
- techniques: spectroscopic;
- stars: emission-line;
- Be;
- stars: fundamental parameters;
- stars: rotation;
- Astrophysics
- E-Print:
- 8 pages, 3 figures, shortened Sec. 6.3, new Sec. 6.4. Accepted by MNRAS