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| Paper: |
Discovery of Carbon Rich X-ray Emission from a Wolf-Rayet Binary θ Muscae |
| Volume: |
361, Active OB-Stars: Laboratories For Stellar and Circumstellar Physics |
| Page: |
500 |
| Authors: |
Sugawara, Y.; Maeda, Y.; Tsuboi, Y.; Yamamoto, A. |
| Abstract: |
With XMM-Newton, we observed a WC6+O9.5 binary θ Muscae (WR48), the second brightest Wolf-Rayet binary in the optical wavelengths, with an orbital period of 19.1375 days. The observation was executed on 20–21 July 2004 with 1.3 days exposure, when the O star was located in front of the WR star. We made X-ray spectra with gratings (RGS 1 and 2), which have superb energy resolution in soft X-ray band (0.35–2.5 keV), and CCD cameras (PN, MOS 1 and 2), which have large effective area up to 10 keV. Strong emission lines from various He-like elements are detected. The spectra are fitted well with a multi-temperature thin-thermal plasma model with an absorbing column of NH = 3 × 1021 cm−2. Carbon is an order of magnitude overabundant than those in the Sun. We detected RRC (Radiative Recombination Continuum) structure from oxygen around 0.87 keV as well as that from carbon around 0.49 keV. This implies the existence of the additional cooler component. All the results indicate that strong wind of the WC star has been widely distributed near and far from the binary system, forming plasma in various temperatures, and radiating X-rays. |
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