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[8.15] On the Star-Formation History of the Large Magellanic Cloud

A.A. Cole (University of Massachusetts, Amherst), T.A. Smecker-Hane (University of California, Irvine), J.S. Gallagher, III (University of Wisconsin-Madison)

Using WFPC2, we have obtained deep images in the V and I passbands of two fields in the central Large Magellanic Cloud. From these data, we have constructed high-quality color-magnitude diagrams that extend to I \approx27 and contain ~70,000 stars each. Our CMDs extend over 2.5 magnitudes below the oldest main-sequence turnoff, which will allow us to determine the complete star-formation history of the two LMC fields with unprecedented accuracy. The fields are near the star clusters SL 336 (disk) and HS 275 (bar). We present our first analysis, focusing on the distance, age, and metallicity of the two fields as derived from the red clump and the red giant, asymptotic giant, and horizontal branches. There is evidence for differing histories of star-formation and/or chemical enrichment between the bar and the inner disk.

Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. Partial funding provided by NSF grant AST-9619460 to TSH.