Astronomy and Astrophysics – Astrophysics
Scientific paper
2002-03-18
Astronomy and Astrophysics
Astrophysics
2 tables, 7 figures
Scientific paper
10.1086/340307
We have used the excellent sensitivity of XMM-Newton to obtain the first high-quality X-ray spectrum of a Wolf-Rayet (WR) star which is not known to be a member of a binary system. Our target, the nitrogen-type star WR 110 (= HD 165688) was also observed and detected with the VLA at four different frequencies. The radio data are in excellent agreement with that expected for free-free wind emission. and the ionized mass-loss rate is derived. The X-ray emission measure distribution shows a dominant contribution from cool plasma at kT$_{cool}$ = 0.5 keV (6 MK) which is only weakly absorbed. We argue that this cool emission originates at hundreds of radii if the wind is spherical and homogeneous and derive shock velocities and the X-ray filling factor using radiative shock models. A surprising result is the unambiguous detection of a hard X-ray component clearly seen in the hard-band images and the spectra. This hard component accounts for about half of the observed flux and can be acceptably fitted by a hot optically thin thermal plasma or a power-law model. If the emission is thermal, then a temperature kT$_{hot}$ $\geq$ 3 keV is derived. Such high temperatures are not predicted by current instability-driven wind shock models. We examine several alternatives and show that the hard emission could be accounted for by the WR wind shocking onto a close stellar companion which has so far escaped detection. However, until persuasive evidence for binarity is found we are left with the intriguing possibility that the hard X-ray emission is produced entirely by the Wolf-Rayet star.
Guedel Manuel
Schmutz Werner
Skinner Stephen Lee
Zhekov Svetozar A.
No associations
LandOfFree
XMM-Newton Detection of Hard X-ray Emission in the Nitrogen-Type Wolf-Rayet Star WR110 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with XMM-Newton Detection of Hard X-ray Emission in the Nitrogen-Type Wolf-Rayet Star WR110, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and XMM-Newton Detection of Hard X-ray Emission in the Nitrogen-Type Wolf-Rayet Star WR110 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-576268