[en] We summarize the results of a multiwavelength observing campaign on the massive eclipsing binary CPD-41° 7742, another remarkable object in the young open cluster NGC 6231. Our campaign relies on high resolution echelle spectroscopy, narrow-band optical photometry, and XMM-Newton X-ray observations. Combined with the spectroscopic analysis, the light curve analysis provides a direct measurement of the masses and sizes of the system components. However, the most outstanding results come from the XMM observations. Our 180 ks campaign towards NGC 6231, and CPD-41° 7742, provides an unprecedented phase coverage of such a close early-type binary. The EPIC-MOS light curves almost fully cover the 2.4 day period of the system and the brightness of the object is sufficient to yield a time resolution as tight as 1 ks. The X-ray flux presents clear variations along the orbit, that we interpret as the signature of an unusual wind interaction. We indeed expect that, in this O+B system, the dominant primary wind crashes into the secondary surface, leading to a wind-photosphere interaction. As a strong support to our interpretation, we provide a geometrical model that associates an extra X-ray emission to the secondary inner surface. Though quite simple, the present model matches the main features of the X-ray light curve.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Sana, H.; Institut d'Astrophysique et de Géophysique, Liège University, Allée du 6 Aout 17, Bat. B5c, B-4000 Liège, Belgium) AB(Institut d'Astrophysique et de Géophysique, Liège University, Allée du 6 Aout 17, Bat. B5c, B-4000 Liège, Belgium) AC(Institut d'Astrophysique et de Géophysique, Liège University, Allée du 6 Aout 17, Bat. B5c, B-4000 Liège, Belgium) AD(Sternberg Astronomical Institute, Moscow State University, Universitetskii pr., 13, 119899 Moscow, Russia) AE(Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200 B, B-3001 Leuven, Belgium) AF(Institut d'Astrophysique et de Géophysique, Liège University, Allée du 6 Aout 17, Bat. B5c, B-4000 Liège, Belgium) AG(Institut d'Astrophysique et de Géophysique, Liège University, Allée du 6 Aout 17, Bat. B5c, B-4000 Liège, Belgium
Gosset, Eric ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE)
Rauw, Grégor ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE) - Sciences spatiales
Antokhina, E.
Royer, P.
Manfroid, Jean ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO)
Vreux, Jean-Marie ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO)
Language :
English
Title :
CPD-41° 7742: an unusual wind interaction
Publication date :
01 November 2005
Audience :
International
Main work title :
Massive Stars and High-Energy Emission in OB Associations