Towards an understanding of the Of?p star HD 191612: Optical spectroscopy

Ian D. Howarth, Nolan R. Walborn, Danny J. Lennon, Joachim Puls, Yaël Nazé, K. Annuk, I. Antokhin, D. Bohlender, H. Bond, J. F. Donati, L. Georgiev, D. Gies, D. Harmer, A. Herrero, I. Kolka, D. McDavid, T. Morel, I. Negueruela, G. Rauw, P. Reig

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


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 languageEnglish (US)
Pages (from-to)433-446
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Oct 2007

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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