Article (Scientific journals)
First Orbital Solution for the Non-thermal Emitter Cyg OB2 No. 9
Nazé, Yaël; Damerdji, Yassine; Rauw, Grégor et al.
2010In Astrophysical Journal, 719, p. 634-641
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Keywords :
binaries: spectroscopic; stars: early-type; stars: emission-line; Be; stars: individual: Cyg OB2 No. 9; X-rays: stars
Abstract :
[en] After the first detection of its binary nature, the spectroscopic monitoring of the non-thermal radio emitter Cyg OB2 No. 9 (P = 2.4 yr) has continued, doubling the number of available spectra of the star. Since the discovery paper of 2008, a second periastron passage has occurred in 2009 February. Using a variety of techniques, the radial velocities could be estimated and a first, preliminary orbital solution was derived from the He I 5876 line. The mass ratio appears close to unity and the eccentricity is large, i.e., 0.7-0.75. X-ray data from 2004 and 2007 are also analyzed in quest of peculiarities linked to binarity. The observations reveal neither large overluminosity nor strong hardness, but it must be noted that the high-energy data were taken after the periastron passage, at a time where colliding wind emission may be low. Some unusual X-ray variability is however detected, with a 10% flux decrease between 2004 and 2007. To clarify their origin and find a more obvious signature of the wind-wind collision, additional data, taken at periastron and close to it, are needed. Based on observations collected at the Haute-Provence Observatory and with XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Nazé, Yaël  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique observationnelle (sol et espace)
Damerdji, Yassine ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Rauw, Grégor  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Sciences spatiales
Kiminki, D. C.;  Department of Physics & Astronomy, University of Wyoming, Laramie, WY 82070, USA
Mahy, Laurent ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique observationnelle (sol et espace)
Kobulnicky, H. A.;  Department of Physics & Astronomy, University of Wyoming, Laramie, WY 82070, USA
Morel, Thierry  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE)
De Becker, Michaël  ;  Université de Liège - ULiège > 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
Barbieri, C.;  Dipartimento di Astronomia, Universitá degli studi di Padova, vicolo Osservatorio 2, 35122 Padova, Italy
Language :
English
Title :
First Orbital Solution for the Non-thermal Emitter Cyg OB2 No. 9
Publication date :
01 August 2010
Journal title :
Astrophysical Journal
ISSN :
0004-637X
eISSN :
1538-4357
Publisher :
University of Chicago Press, United States - Illinois
Volume :
719
Pages :
634-641
Peer reviewed :
Peer Reviewed verified by ORBi
Commentary :
http://de.arxiv.org/abs/1006.2917
Available on ORBi :
since 13 November 2010

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