Abstract
We present extensive optical spectroscopy of the early-type magnetic star HD 191612 (O6.5f?pe-O8fp). The Balmer and He i lines show strongly variable emission which is highly reproducible on a well-determined 538-d period. He ii absorptions and metal lines (including many selective emission lines but excluding He ii λ4686 Å emission) are essentially constant in line strength, but are variable in velocity, establishing a double-lined binary orbit with Porb = 1542 d, e = 0.45. We conduct a model-atmosphere analysis of the spectrum, and find that the system is consistent with a ∼O8 giant with a ∼B1 main-sequence secondary. Since the periodic 538-d changes are unrelated to orbital motion, rotational modulation of a magnetically constrained plasma is strongly favoured as the most likely underlying 'clock'. An upper limit on the equatorial rotation is consistent with this hypothesis, but is too weak to provide a strong constraint.
Original language | English (US) |
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Pages (from-to) | 433-446 |
Number of pages | 14 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 381 |
Issue number | 2 |
DOIs | |
State | Published - Oct 2007 |
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science