Annu. Rev. Astron. Astrophys. 1989. 27: 139-59
Copyright © 1989 by . All rights reserved

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5.13 Leo I

The two dwarf elliptical galaxies in Leo are both about three times as distant as Sculptor, and consequently they have not been as thoroughly studied. Leo I has had the further disadvantage of lying so close in the sky to the star Regulus that it is difficult to work on without concern for scattered light, or even without saturating whatever detector is being used. A color-magnitude diagram has been published for its giants by Fox & Pritchet (42), who showed that its dominant population is of old, red stars.

Hodge & Wright (73) found a large population of anomalous Cepheids, which they interpreted to indicate a significant fraction of stars more massive than the turnoff. A carbon star was reported by Aaronson et al. (6), and subsequent searches by Azzopardi et al. (9, 10) have turned up an additional 18. As discussed by Richer & Westerlund (103), Aaronson et al. (6), and others, the relative number of carbon stars is correlated with the heavy-element abundances in a galaxy. Leo I's large number of carbon stars goes along with its low abundances. [Suntzeff et al. (120) derive [Fe/H] = -1.5 ± 0.25.]