MICROLENSING EVENTS OF THE LMC ARE BETTER EXPLAINED BY STARS WITHIN THE LMC THAN BY MACHOS

The recently reported microlensing events of the LMC have caused much excitement, and have been interpreted as due to ''dark objects'' (MACH Os) in the halo of our Galaxy. It is shown here that stars within the LMC play a dominant role as gravitational lenses and can indeed accoun t for the observed events. For observations within the bar of the LMC, the probability of microlensing being caused by a star within the LMC is found to be similar to 5 X 10(-8). Outside of the bar, the probabi lity of microlensing being caused by a star in the LMC is 4-12 times l ower. The MACHO event (Alcock et al. 1993) and one of the EROS events (Aubourg et al. 1993) lie within the bar for which the probability of microlensing is consistent with being caused by an object within the L MC. If stars within the LMC play a dominant role as lenses, the events should be concentrated towards the center of the LMC. On the other ha nd, if MACHOs play a dominant role as lenses then, for a given number of monitored stars, the events should be uniformly distributed over th e whole area of the LMC. Thus the galactic and the LMC lenses can be s tatistically distinguished in most cases. It is further shown that, un der certain conditions, the light curve of an event caused by a star w ithin the LMC would be different from the one caused by a MACHO. This can also be a distinguishing signature, and seems to have been observe d in case of the MACHO event. The fit discrepancy near the peak which the authors say ''is not yet understood'' is reduced if the event is c aused by an object within the LMC, which further suggests that the len sing is due to a low-mass star within the LMC itself.