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Symposium 241

Abstract details

The Recent Star Formation Histories of Nearby Galaxies
Evan Skillman

Recent (< 0.5 Gyr) star formation histories have a large impact on the observable properties of galaxies. Using HST/ACS we have constructed spatially resolved star formation histories of M81 group dwarf galaxies with a time resolution of roughly 30 Myr over the last 500 Myr. We have designed a sample of ten galaxies spanning ranges of 6 magnitudes in luminosity, 1000 in current star formation rate, and 0.5 dex in metallicity. The ACS observations allow us to directly observe the strength and spatial relationships of all of the recent star formation in these galaxies. These observations are complemented by high-quality ancillary data {e.g., Spitzer, UV/optical/H-alpha/NIR, VLA HI}. Our resolved star formation maps will be compared with star formation rates inferred from H-alpha, UV, and IR observations - allowing an independent calibration of these techniques. Given the ranges in metallicity, these observations will provide calibrations of stellar evolution tracks for young, low metallicity stars. These observations will also enable us to construct prescriptions of how star formation and feedback depend on metallicity, size, gas content, and current star formation rates in galaxies. Finally, I will describe the ANGST (ACS Nearby Galaxies Survey Treasury Program) and ANGRRR (Archive of Nearby Galaxies: Reduce, Reuse, Recycle) HST programs.

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