Extraordinarily Hot X-Ray Emission from the O9 Emission-Line Star HD 119682

Abstract

We present new optical and X-ray observations to show that the X-ray source 1 WGA J1346.5–6255 previously associated with the SNR G309.2–0.6 can be unequivocally identified with the emission line star HD 119682 located in the foreground open cluster NGC 5281. Images from Chandra in the X-ray band as well as from Magellan in the narrow optical H-alpha band show a coincidence of the source positions within 0.5". The X-ray source appears extremely hot for an OB-star identified as of O9.7e type. XMM-Newton spectra show plasma temperatures of 1 keV and 8 keV with an X-ray luminosity of 6.2E32 +/-0.1E32 erg/s. The optical and X-ray properties are very reminiscent of the prototype emission line star Gamma-Cas. We discuss the ramifications of this similarity with respect to very early type emission line stars as a new class of hard X-ray sources.