Long-Term Variations of the Black-Hole Binary LMC X-3
Abstract
Recent analysis of X-ray data from HEAO-1 and Ginga shows that the X-ray luminosity of the black-hole binary LMC X-3, long known to be highly variable, is modulated with either a double-peaked ~200-day period or a single-peaked ~100-day period. Because the variation is so regular, it seems likely that the periodicity is related to some "clock" in the system, such as a precessing accretion disk similar to those in Her X-1 or SS433. From the X-ray data alone, it is not clear what the most appropriate physical model for this variability is. Selected ultraviolet observations at certain phases in the long-term cycle may allow us to discriminate been various models of the accretion disk. Seven short-wavelength archival spectra are available, but because LMC X-3 varies throughout the 1.7-day orbital cycle, the existing data are insufficient to separate these two very different variations (orbital and long-term). We wish to obtain IUE spectra at selected long-period phases, but always observing at the same orbital phase. This will allow us to study the long-term variations without interference from the orbital changes.
- Publication:
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IUE Proposal
- Pub Date:
- 1991
- Bibcode:
- 1991iue..prop.3952C