The Populations of Carina. II. Chemical Enrichment
  Chemical abundances are presented for 19 elements in a sample of 63 red
giants in the Carina dwarf spheroidal galaxy (dSph), based on homogeneous
1D/LTE model atmosphere analyses of our own observations (32 stars) and data
available in the literature (a further 31 independent stars). The (Fe)
metallicity and [$\alpha$/Fe] distribution functions have mean values and
dispersions of -1.59 and 0.33 dex ([Fe/H] range: -2.68 to -0.64), and 0.07 and
0.13 dex ([$\alpha$/Fe] range: -0.27 to 0.25), respectively. We confirm the
finding of Venn et al. (2012) that a small percentage (some 10% in the present
investigation) of the sample show clear evidence for significant enrichment by
Type Ia supernovae ejecta. Calcium, with the most accurately determined
abundance of the alpha-elements, shows an asymmetric distribution towards
smaller values of [Ca/Fe] at all [Fe/H], most significantly over -2.0 < [Fe/H]
< -1.0, suggestive of incomplete mixing of the ejecta of Type Ia SNe with the
ambient medium of each of Carina's generations. Approximate
color-magnitude-diagram age estimates are presented for the sample and,
together with our chemical abundances, compared with the results of our
previous synthetic CMD analysis, which reported the details of Carina's four
well-defined populations.
  We searched for the Na-O anti-correlation universally reported in the
Galaxy's globular clusters, and confirm that this phenomenon does not exist in
Carina. We also found that one of the 32 stars in our sample has an extremely
enhanced lithium abundance -- A(Li)$_{\text{NLTE}}$ = +3.36, consistent with
membership of the ~1% group of Li-rich stars in dSph described by Kirby et al.
