We present a simple test that can distinguish between the light curves of candidate microlensing events and those of some dwarf nova eruptions that have a similar morphology. We find that the distribution of the amplitudes versus durations of ordinary dwarf nova eruptions is significantly different from that exhibited by the main body of 53 microlensing candidates discovered by the MACHO and OGLE collaborations. The most serious source of potential contamination may be due to old novae that exhibit dwarf nova outbursts. By adopting the current estimates for the space density of such old novae, we find that a significant fraction of the microlensing candidates could be cataclysmic variables.
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