[en] Using a set of high-resolution spectra, we studied the physical and orbital properties of the O-type binary CPD -41 7733, located in the core of NGC 6231. We report the unambiguous detection of a secondary spectral signature and we derive the first SB2 orbital solution of the system. The period is 5.6815 + 0.0015 days, and the orbit has no significant eccentricity. CPD -41 7733 probably consists of stars of spectral types O8.5 and B3. As for other objects in the cluster, we observe discrepant luminosity classifications while using spectroscopic or brightness criteria. Still, the present analysis suggests that both components display physical parameters close to those of typical O8.5 and B3 dwarfs. We also analyze the X-ray light curves and spectra obtained during six 30 ks XMM-Newton pointings spread over the 5.7 day period. We find no significant variability between the different pointings, nor within the individual observations. The CPD - 41 7733 X- ray spectrum is well reproduced by a three-temperature thermal mekal model with temperatures of 0.3, 0.8, and 2.4 keV. No X-ray overluminosity, resulting, e. g., from a possible wind interaction, is observed. The emission of CPD -41 7733 is thus very representative of typical O-type star X- ray emission.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Sana, H.
Rauw, Grégor ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE)
Gosset, Eric ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE)
Language :
English
Title :
Constraining the fundamental parameters of the O-type binary CPD-41 7733
Publication date :
20 April 2007
Journal title :
Astrophysical Journal
ISSN :
0004-637X
eISSN :
1538-4357
Publisher :
Univ Chicago Press, Chicago, United States - Illinois
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