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Session 66 - Galaxies.
Display session, Thursday, June 11
Atlas Ballroom,

[66.16] HST/WFPC2 Observations of Stellar Populations in the LMC Field

M. Geha, J. Holtzman (NMSU), WFPC2 IDT

We have analyzed three HST fields in the outer disk of the Large Magellanic Clouds at different azimuthal positions to determine the star formation history in these regions. We do not detect any strongly significant differences in the stellar populations of the three fields based on the morphologies of the color-magnitude diagrams and the luminosity functions, suggesting similar star formation histories in these regions. We compare the observed stellar population with those predicted from several simple star formation histories suggested in the literature. The only model validated by the observations is one in which the star formation rate is roughly constant for most of the LMC's history and then increases by a factor of three about 2 Gyr ago. Such a model has roughly equal numbers of stars older and younger than 4 Gyr, and thus is not dominated by young stars. An analysis of the lower main sequence in our fields does not support the suggestion of Zaritsky amp; Lin (AJ 114:2545) for an intervening stellar population towards the LMC.

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