X-Ray Emission from Massive Stars in Cyg OB2
Date Issued
2015
Author(s)
Rauw, G.
•
Nazé, Y.
•
Wright, N. J.
•
Drake, J. J.
•
•
Prinja, R. K.
•
Peck, L. W.
•
Albacete Colombo, J. F.
•
Herrero, A.
•
Kobulnicky, H. A.
•
•
Vink, J. S.
Description
The Liège team acknowledges support from Belspo through an XMM PRODEX contract, from the FRS/FNRS and from an ARC grant for Concerted Research Actions, financed by the Federation Wallonia-Brussels. N.J.W. was supported by a Royal Astronomical Society research fellowship. Facilities: CXO , XMM .
Abstract
We report on the analysis of the Chandra-ACIS data of O, B, and WR stars in the young association Cyg OB2. X-ray spectra of 49 O-stars, 54 B-stars, and 3 WR-stars are analyzed and for the brighter sources, the epoch dependence of the X-ray fluxes is investigated. The O-stars in Cyg OB2 follow a well-defined scaling relation between their X-ray and bolometric luminosities: {log}\\frac{{L}{{X}}}{{L}{bol}}=-7.2+/- 0.2. This relation is in excellent agreement with the one previously derived for the Carina OB1 association. Except for the brightest O-star binaries, there is no general X-ray overluminosity due to colliding winds in O-star binaries. Roughly half of the known B-stars in the surveyed field are detected, but they fail to display a clear relationship between LX and Lbol. Out of the three WR stars in Cyg OB2, probably only WR 144 is itself responsible for the observed level of X-ray emission, at a very low {log}\\frac{{L}{{X}}}{{L}{bol}}=-8.8+/- 0.2. The X-ray emission of the other two WR-stars (WR 145 and 146) is most probably due to their O-type companion along with a moderate contribution from a wind-wind interaction zone.
Volume
221
Issue
1
Start page
1
Issn Identifier
0067-0049
Ads BibCode
2015ApJS..221....1R
Rights
open.access
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