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) |
|---|---|
| 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 1 2007 |
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All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
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Towards an understanding of the Of?p star HD 191612 : Optical spectroscopy. / Howarth, Ian D.; Walborn, Nolan R.; Lennon, Danny J.; Puls, Joachim; Nazé, Yaël; Annuk, K.; Antokhin, I.; Bohlender, D.; Bond, Howard E.; Donati, J. F.; Georgiev, L.; Gies, D.; Harmer, D.; Herrero, A.; Kolka, I.; McDavid, D.; Morel, T.; Negueruela, I.; Rauw, G.; Reig, P.
In: Monthly Notices of the Royal Astronomical Society, Vol. 381, No. 2, 01.10.2007, p. 433-446.Research output: Contribution to journal › Article
TY - JOUR
T1 - Towards an understanding of the Of?p star HD 191612
T2 - Optical spectroscopy
AU - Howarth, Ian D.
AU - Walborn, Nolan R.
AU - Lennon, Danny J.
AU - Puls, Joachim
AU - Nazé, Yaël
AU - Annuk, K.
AU - Antokhin, I.
AU - Bohlender, D.
AU - Bond, Howard E.
AU - Donati, J. F.
AU - Georgiev, L.
AU - Gies, D.
AU - Harmer, D.
AU - Herrero, A.
AU - Kolka, I.
AU - McDavid, D.
AU - Morel, T.
AU - Negueruela, I.
AU - Rauw, G.
AU - Reig, P.
PY - 2007/10/1
Y1 - 2007/10/1
N2 - 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.
AB - 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.
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U2 - 10.1111/j.1365-2966.2007.12178.x
DO - 10.1111/j.1365-2966.2007.12178.x
M3 - Article
VL - 381
SP - 433
EP - 446
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 2
ER -