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The chemical evolution of subpopulations in the Carina dwarf spheroidal

Published online by Cambridge University Press:  08 November 2005

A. Koch
Affiliation:
Astronomical Institute of the University of Basel, Venusstr. 7, 4102 Binningen, Switzerland email: koch@astro.unibas.ch
M. Wilkinson
Affiliation:
Institute of Astronomy, Cambridge University, Madingley Road, Cambridge CB3 0HA, UK
E.K. Grebel
Affiliation:
Astronomical Institute of the University of Basel, Venusstr. 7, 4102 Binningen, Switzerland email: koch@astro.unibas.ch
D. Harbeck
Affiliation:
University of California, Space Sciences Laboratory, 7 Gauss Way, Berkeley, CA 940720
J. Kleyna
Affiliation:
Institute for Astronomy, University of Hawaii, 260 Woodlawn Drive, Honolulu, HI 96822
R. Wyse
Affiliation:
The John Hopkins University, 3701 San Martin Drive, Baltimore, MD 21218
G. Gilmore
Affiliation:
Institute of Astronomy, Cambridge University, Madingley Road, Cambridge CB3 0HA, UK
W. Evans
Affiliation:
Institute of Astronomy, Cambridge University, Madingley Road, Cambridge CB3 0HA, UK
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Abstract

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We present the observed metallicity distribution for 437 red giants in the Carina dwarf spheroidal (dSph) galaxy that was derived from FLAMES medium-resolution spectroscopy of the near-infrared Ca triplet (CaT). We find a mean [Fe/H] of −1.7, dex and a full spread in metallicities of at least one dex. Most of this width is due to the occurrence of three populations at different [Fe/H], which are likely to be related to the three star forming (SF) episodes that governed Carina's evolution and also correlate with peaks in the age-distribution. Both the lack of any correlation between stellar colour and metallicity and a comparison of the metallicities with chemical evolution models, which suggest a major role of infalling gas, contribute to the detailed understanding of Carina's evolutionary history. Moreover, we find a mild dependence of metallicity on radial location, reflected in a shift of the distribution's peak towards the metal poor end in the outer regions.

Type
Contributed Papers
Copyright
© 2005 International Astronomical Union