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The Star Formation History of Leo I

Published online by Cambridge University Press:  25 May 2016

C. Gallart  and
W. L. Freedman
C. Gallart
Affiliation:
Carnegie Observatories. 813 Santa Barbara St. Pasadena CA 91101, USA
W. L. Freedman
Affiliation:
Carnegie Observatories. 813 Santa Barbara St. Pasadena CA 91101, USA

Abstract

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We advance some results of our study of the star formation history of the Local Group dSph galaxy Leo I, obtained through the analysis of its deep HST color-magnitude diagram (CMD) using model CMDs computed from stellar evolutionary models. We conclude that most star formation (≃ 90%) took place in Leo I between 7 and 1 Gyr ago. It seems to have started at a very low rate ≃ 15 Gyr ago and continued, also at a very low rate, from 1 Gyr ago until the present time. A constant Z=0.0004 and a large fraction of binary stars are required to obtain the best agreement with both the distribution of stars across the CMD and with its morphology. An IMF like the one obtained by Kroupa et al. (1993) for the solar neighborhood, or steeper, is compatible with the data.

Type
Part 2: The Database
Information
Symposium - International Astronomical Union , Volume 192: The Stellar Content of Local Group Galaxies , 1999 , pp. 151 - 157
Copyright
Copyright © Astronomical Society of the Pacific 1999 

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