Color-magnitude diagram constraints on the metallicities, ages, and star formation history of the stellar populations in the carina dwarf spheroidal galaxy

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DOIResolve DOI: http://doi.org/10.1088/0004-637X/805/2/103
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TypeArticle
Journal titleThe Astrophysical Journal
ISSN0004-637X
Volume805
Issue2
Article number103
Subjectgalaxies; abundances; dwarf; individual(Carina); stellar content; globular clusters; individual(M3, M92); stars evolution
AbstractVictoria-Regina isochrones for -0.4≤ [α/Fe] ≤ +0.4 and a wide range in [Fe/H], along with complementary zero-age horizontal branch (ZAHB) loci, have been applied to the colormagnitude diagram (CMD) of Carina. The color transformations that we have used have been calibrated so that isochrones provide excellent fits to the [(B - V)0 Mv] diagrams of M3 and M92 when well supported estimates of the globular cluster (GC) reddenings and metallicities are assumed. The adopted distance moduli, for both the GCs and Carina, are based on our ZAHB models, which are able to reproduce the old horizontal branch (HB) component (as well as the luminosity of the HB clump) of the dwarf spheroidal galaxy quite welleven if it spans a range in [Fe/H] of ∼1.5 dex, provided that [α/Fe] varies with [Fe/H] in approximately the way that has been derived spectroscopically. Ages derived here agree reasonably well with those found previously for the old and intermediate-age turnoff (TO) stars, as well as for the period of negligible star formation (SF) activity (∼610 Gyr ago). CMD simulations have been carried out for the faintest TO and subgiant stars. They indicate a clear preference for SF that lasted several Gyr instead of a short burst, with some indication that ages decrease with increasing [Fe/H]. In general, stellar models that assume spectroscopic metallicities provide satisfactory fits to the observations, including the thin giant branch of Carina, though higher oxygen abundances than those implied by the adopted values of [α/Fe] would have favorable consequences.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); NRC Herzberg Institute of Astrophysics
Peer reviewedYes
NPARC number21277059
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Record identifierb2cf7157-89b5-4372-a529-4f3ab00adf3a
Record created2015-11-10
Record modified2016-07-18
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