ORBi: Howarth Ian D. - Towards an understanding of the Of ? p star HD 191612: optical spectroscopy

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


	Document type :	Scientific journals : Article
	Discipline(s) :	Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
	To cite this reference:	http://hdl.handle.net/2268/1835

Title :	Towards an understanding of the Of ? p star HD 191612: optical spectroscopy
Language :	English
Author, co-author :	Howarth, Ian D. [> > > >]
	Walborn, Nolan R. [> > > >]
	Lennon, Danny J. [> > > >]
	Puls, Joachim [> > > >]
	Nazé, Yaël [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE) >]
	Annuk, K. [> > > >]
	Antokhin, I. [> > > >]
	Bohlender, D. [> > > >]
	Bond, H. [> > > >]
	Donati, J. F. [> > > >]
	Georgiev, L. [> > > >]
	Gies, D. [> > > >]
	Harmer, D. [> > > >]
	Herrero, A. [> > > >]
	Kolka, I. [> > > >]
	McDavid, D. [> > > >]
	Morel, Thierry [Katholieke Universiteit Leuven, Departement Natuurkunde en Sterrenkunde, Instituut voor Sterrenkunde, Celestijnenlaan 200D, 3001 Leuven, Belgium > > > >]
	Negueruela, I. [> > > >]
	Rauw, Grégor [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE) >]
	Reig, P. [> > > >]
Publication date :	21-Oct-2007
Journal title :	Monthly Notices of the Royal Astronomical Society
Publisher :	Blackwell Publishing
Volume :	381
Issue/season :	2
Pages :	433-446
Audience :	International
ISSN :	0035-8711
City :	Oxford
Keywords :	[en] stars : binaries : spectroscopic ; stars : early-type ; stars : individual : HD 191612 ; stars : magnetic fields ; stars : rotation
Abstract :	[en] 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 lambda 4686 angstrom emission) are essentially constant in line strength, but are variable in velocity, establishing a double-lined binary orbit with P-orb = 1542 d, e = 0.45. We conduct a model-atmosphere analysis of the spectrum, and find that the system is consistent with a similar to O8 giant with a similar to 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.
Target :	Researchers ; Professionals
Permalink :	http://hdl.handle.net/2268/1835
DOI :	10.1111/j.1365-2966.2007.12178.x
Other URL :	http://arxiv.org/abs/0707.0594

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