ORBi: Rauw Grégor - 9 Sagittarii: uncovering an O-type spectroscopic binary with an 8.6 year period

Reference : 9 Sagittarii: uncovering an O-type spectroscopic binary with an 8.6 year period


	Document type :	Scientific journals : Article
	Discipline(s) :	Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
	To cite this reference:	http://hdl.handle.net/2268/125972

Title :	9 Sagittarii: uncovering an O-type spectroscopic binary with an 8.6 year period
Language :	English
Author, co-author :	Rauw, Grégor [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Sciences spatiales >]
	Sana, H. [Sterrenkundig Instituut "Anton Pannekoek", Universiteit van Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands]
	Spano, M. [Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290, Sauverny, Switzerland]
	Gosset, Eric [Université de Liège - ULg > > GAPHE : Astrophysique observationnelle (sol et espace) >]
	Mahy, Laurent [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Sciences spatiales >]
	De Becker, Michaël [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO) >]
	Eenens, P. [Departamento de Astronomia, Universidad de Guanajuato, Apartado 144, 36000, Guanajuato, GTO, Mexico)]
Publication date :	1-Jun-2012
Journal title :	Astronomy and Astrophysics
Publisher :	EDP Sciences
Volume :	542
Pages :	A95
Audience :	International
ISSN :	0004-6361
e-ISSN :	1432-0746
City :	Les Ulis
Country :	France
Keywords :	[en] stars: early-type ; binaries: spectroscopic ; stars: fundamental parameters ; stars: massive ; stars: individual: 9 Sgr
Abstract :	[en] Context. The O-type object 9 Sgr is a well-known synchrotron radio emitter. This feature is usually attributed to colliding-wind binary systems, but 9 Sgr was long considered a single star. <BR /> Aims: We have conducted a long-term spectroscopic monitoring of this star to investigate its multiplicity and search for evidence for wind-wind interactions. <BR /> Methods: Radial velocities are determined and analysed using various period search methods. Spectral disentangling is applied to separate the spectra of the components of the binary system. <BR /> Results: We derive the first ever orbital solution of 9 Sgr. The system is found to consist of an O3.5 V((f[SUP]+[/SUP])) primary and an O5-5.5 V((f)) secondary moving around each other on a highly eccentric (e = 0.7), 8.6 year orbit. The spectra reveal no variable emission lines that could be formed in the wind interaction zone in agreement with the expected properties of the interaction in such a wide system. <BR /> Conclusions: Our results provide further support to the paradigm of synchrotron radio emission from early-type stars being a manifestation of interacting winds in a binary system. Based on observations collected at the European Southern Observatory (La Silla, Chile and Cerro Paranal, Chile) and the San Pedro Mártir observatory (Mexico).Appendix A is available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A>The reduced spectra are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/542/A95">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/542/A95</A>
Permalink :	http://hdl.handle.net/2268/125972
DOI :	10.1051/0004-6361/201219254
Other URL :	http://adsabs.harvard.edu/abs/2012A%26A...542A..95R
	http://de.arxiv.org/abs/1205.3314

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