Abstract
We observed a field in the disk of the LMC on two consecutive nights in search of rapid variable stars. We found two pulsating stars of type RRab and δ Scuti and four binary stars; among the latter we found one sdB or cataclysmic variable below the LMC blue main sequence and three very close binary systems on the main sequence. At least one of the main-sequence binaries, and possibly all three, are the first solar-type (W UMa–type) contact binaries to be detected in any extragalactic system and observed to obey the same MV = MV(log P, B - V) calibration as the Galactic systems. Given the selection effects due to small amplitudes at faint magnitudes, the frequency of such binaries in the disk of the LMC with its large spread in population ages is not inconsistent with that in the disk of our Galaxy and contrasts with the lack of binaries found in earlier observations of the much younger LMC cluster LW 55.
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Footnotes
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Based on data obtained at Las Campanas Observatory, operated by the Carnegie Institution of Washington, during the University of Toronto time allocation.