Reference : XMM-Newton high-resolution X-ray spectroscopy of the Wolf-Rayet object WR 25 in the C...
Scientific journals : Letter to the editor
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
XMM-Newton high-resolution X-ray spectroscopy of the Wolf-Rayet object WR 25 in the Carina OB1 association
Raassen, A. J. J. [> > > >]
van der Hucht, K. A. [> > > >]
Mewe, R. [> > > >]
Antokhin, I. [> > > >]
Rauw, Grégor mailto [Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE) >]
Vreux, Jean-Marie mailto [Université de Liège - ULiège > Département d'astrophysique]
Schmutz, W. [> > > >]
Gudel, M. [> > > >]
Astronomy and Astrophysics
E D P Sciences
Yes (verified by ORBi)
Les Ulis Cedexa
[en] stars : individual : WR25 ; stars : early-type ; stars : Wolf-Rayet ; stars : binaries : general ; stars : abundances ; X-rays : stars
[en] We report the analysis of the first high-resolution X-ray spectra of the Wolf-Rayet (WR) object WR25 (HD 93162, WN6ha+O4f) obtained with the reflection Grating spectrometers (RGS) and the European photon imaging cameras (EPIC-MOS and PN) CCD spectrometers on board the XMM-Newton satellite. The spectrum exhibits bright emission lines of the H- and He-like ions of Ne, Mg, Si and S, as well as Fe XVIII to Fe XX and Fe XXV lines. Line fluxes have been measured. The RGS and e pi c spectra have been simultaneously fitted to obtain self-consistent temperatures, emission measures, and elemental abundances. Strong absorption by the dense WR stellar wind and the interstellar medium (ISM) is observed equivalent to N-H = 7x10(21) cm(-2). Multi-temperature (DEM) fitting yields two dominant components around temperatures of 7.0 and 32 MK, respectively. The XMM intrinsic (i.e. unabsorbed, corrected for the stellar wind absorption and the absorption of ISM) X-ray luminosity of WR25 is L-x(0.5-10 keV) = 1.3x10(34) erg s(-1), and L-x(0.5-10 keV) = 0.85 x 10(34) erg s(-1), (when correcting for the ISM only) assuming d = 3.24 kpc. The obtained chemical abundances are subsolar, except for S. This may be real, but could equally well be due to a weak coupling to the continuum, which is strongly influenced by the absorption column density and the subtracted background. The expected high N-abundance, as observed in the optical wavelength region, could not be confirmed due to the strong wind absorption, blocking out its spectral signature. The presence of the Fe XXV emission-line complex at similar to6.7 keV is argued as being indicative for colliding winds inside a WR+O binary system.

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