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We present results of a Chandra High Energy Transmission Grating (HETG)observation of the carbon-rich Wolf-Rayet (WR) star WR48a. These are the firsthigh-resolution spectra of this object in X-rays. Blue-shifted centroids of thespectral lines of about -360 km/s and line widths of 1000 - 1500 km/s (FWHM)were deduced from the analysis of the line profiles of strong emission lines.The forbidden line of Si XIII is strong and not suppressed, indicating that therarefied 10-30 MK plasma forms far from strong sources of far-UV emission, mostlikely in a wind collision zone. Global spectral modeling showed that the X-rayspectrum of WR48a suffered higher absorption in the October 2012 Chandraobservation compared to a previous January 2008 XMM-Newton observation. Theemission measure of the hot plasma in WR48a decreased by a factor ~ 3 over thesame period of time. The most likely physical picture that emerges from theanalysis of the available X-ray data is that of colliding stellar winds in awide binary system with an elliptical orbit. We propose that the unseensecondary star in the system is another WR star or perhaps a luminous bluevariable.

A Chandra Grating Observation of the Dusty Wolf-Rayet Star WR48a