AAS 203rd Meeting, January 2004
Session 105 Dwarf, Irregular, LUM IR and Starburst Galaxies
Oral, Wednesday, January 7, 2004, 2:00-3:30pm, Regency VII

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[105.06] Chemical Evolution and Star-Formation History of the Large Magellanic Cloud

A.A. Cole (Kapteyn Astronomical Institute), T.A. Smecker-Hane (University of California, Irvine), J.S. Gallagher (University of Wisconsin--Madison), E. Tolstoy (Kapteyn Astronomical Institute)

As the nearest galaxy of significant size, the Large Magellanic Cloud is a critical laboratory in which to look for answers to challenging questions of the formation, history, and chemical evolution of galaxies. However, the history of its field star formation and chemical evolution are not yet known with high precision or spatiotemporal resolution. We have used the WFPC2 camera aboard the Hubble Space Telescope to create deep color-magnitude diagrams containing ~105 stars for three fields in the disk and central bar of the LMC. The CMDs are supplemented by chemical abundance information for more than 600 red giants in the same fields obtained from measurements of the near-infrared calcium II triplet lines. Both the CMDs and the metallicity distributions show strong differences between the stellar populations of the inner disk (within 2 kpc of the center), and the center of the bar. A consistent picture is achieved if star formation in the inner disk has been roughly constant or slightly declining over the past 10 Gyr, while the bar experienced a significant increase in star formation rate some 3-5 Gyr ago. The mean metallicity of red giants in the bar is higher than those in the disk, most likely owing to their younger age, coupled with a metallicity that increases with time.

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.