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The LMC Supersoft X-Ray Binary RX J0513.9-6951

David Crampton·J. B. Hutchings·A. P. Cowley·P. C. Schmidtke·T. K. McGrath·D. O'Donoghue·M. K. Harrop-Allin
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Abstract

A detailed analysis of simultaneous photometric and spectroscopic observations of the optical counterpart of the LMC "supersoft" X-ray source RX J0513.9-6951 (identified with HV 5682) is presented. The spectrum is dominated by He II emission lines and H + He II blends; no He I is observed but several higher ionization emission features, especially O VI (3811, 3834, and 5290A) are prominent. Radial velocity measurements suggest a binary period of 0.76 days. If the small velocity amplitude, K~11 km/s, is interpreted as orbital motion, this implies that the binary system contains a somewhat evolved star plus a relatively massive compact object, viewed nearly pole-on. No orbital photometric variations were found, although irregular brightness changes of ~0.3 mag occurred. Unusual emission lines are observed which cannot be identified except as high velocity (4000 km/s) bipolar outflows or jets. These outflows are seen in H and He II at the same positive and negative velocities. They were relatively stable for periods of ~5 days, but their velocities appear to have been ~250 km/s smaller in 1992 than in 1993 or 1994.

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David Crampton, J. B. Hutchings, A. P. Cowley, P. C. Schmidtke, T. K. McGrath, D. O'Donoghue, M. K. Harrop-Allin. 1995-07-07. The LMC Supersoft X-Ray Binary RX J0513.9-6951. https://doi.org/10.1086/176653

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