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The ACS LCID Project: Quantifying the Delayed Star Formation in Leo A


Cole, AA, The ACS LCID Project: Quantifying the Delayed Star Formation in Leo A, Stellar Populations as Building Blocks of Galaxies, 10-16 December, 2006, La Palma, Spain, pp. 295-299. ISBN 0521863503 (2007) [Non Refereed Conference Paper]


We have obtained deep images of the Local Group dwarf irregular galaxy Leo A using the Hubble Space Telescope Advanced Camera for Surveys. From these images we have constructed the deepest ever color-magnitude diagram (CMD) for an irregular galaxy beyond the Magellanic Clouds. We derive the star-formation rate (SFR) as a function of time over the entire history of the galaxy. We find that over 90% of Leo As star formation has occurred more recently than 8 Gyr ago. Our measurements are not inconsistent with a scenario in which all of the ancient star formation occurred prior to the end of the era of reionization, with subsequent suppression until lookback times corresponding to redshift z 1. However, given Leo As strongly isolated state and its dynamical mass of  108 M, its large gas supply was more likely to have been merely heated than driven out of the galaxy altogether.

Item Details

Item Type:Non Refereed Conference Paper
Keywords:galaxies: dwarf, color-magnitude diagrams, galaxies: evolution
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Cosmology and extragalactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Cole, AA (Associate Professor Andrew Cole)
ID Code:71109
Year Published:2007
Deposited By:Physics
Deposited On:2011-07-07
Last Modified:2011-07-07

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