ORBi: Sana H. - The massive star binary fraction in young open clusters

Reference : The massive star binary fraction in young open clusters - I. NGC 6231 revisited


	Document type :	Scientific journals : Article
	Discipline(s) :	Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
	To cite this reference:	http://hdl.handle.net/2268/2684

Title :	The massive star binary fraction in young open clusters - I. NGC 6231 revisited
Language :	English
Author, co-author :	Sana, H. [> > > >]
	Gosset, Eric [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE) >]
	Nazé, Yaël [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Sciences spatiales >]
	Rauw, Grégor [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE) - Sciences spatiales >]
	Linder, Natacha [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE) >]
Publication date :	2008
Journal title :	Monthly Notices of the Royal Astronomical Society
Publisher :	Blackwell Publishing
Volume :	386
Issue/season :	1
Pages :	447-460
Audience :	International
ISSN :	0035-8711
City :	Oxford
Country :	United Kingdom
Keywords :	[en] binaries : general ; binaries : spectroscopic ; stars : early-type ; open clusters and associations : individual : NGC 6231 ; open clusters and associations : individual : Sco OB1 ; binaries : close
Abstract :	[en] We present the results of a long-term high-resolution spectroscopy campaign on the O-type stars in NGC 6231. We revise the spectral classification and multiplicity of these objects and we constrain the fundamental properties of the O-star population. Almost three quarters of the O-type stars in the cluster are members of a binary system. The minimum binary fraction is 0.63, with half the O-type binaries having an orbital period of the order of a few days. The eccentricities of all the short-period binaries are revised downward, and henceforth match a normal period-eccentricity distribution. The mass ratio distribution shows a large preference for O + OB binaries, ruling out the possibility that, in NGC 6231, the companion of an O-type star is randomly drawn from a standard initial mass function. Obtained from a complete and homogeneous population of O-type stars, our conclusions provide interesting observational constraints to be confronted with the formation and early evolution theories of O-stars.
Target :	Researchers ; Professionals
Permalink :	http://hdl.handle.net/2268/2684
DOI :	10.1111/j.1365-2966.2008.13037.x
Other URL :	http://fr.arxiv.org/abs/0707.2847

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