Bibcode
Howarth, Ian D.; Walborn, Nolan R.; Lennon, Danny J.; Puls, Joachim; Nazé, Yaël; Annuk, K.; Antokhin, I.; Bohlender, D.; Bond, H.; Donati, J.-F.; Georgiev, L.; Gies, D.; Harmer, D.; Herrero, A.; Kolka, I.; McDavid, D.; Morel, T.; Negueruela, I.; Rauw, G.; Reig, P.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 381, Issue 2, pp. 433-446.
Fecha de publicación:
10
2007
Número de citas
77
Número de citas referidas
62
Descripción
We present extensive optical spectroscopy of the early-type magnetic
star HD 191612 (O6.5f?pe-O8fp). The Balmer and HeI lines show strongly
variable emission which is highly reproducible on a well-determined
538-d period. HeII absorptions and metal lines (including many selective
emission lines but excluding HeII λ4686 Å emission) are
essentially constant in line strength, but are variable in velocity,
establishing a double-lined binary orbit with Porb = 1542d, 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.