On the central helium-burning variable stars of the LeoI dwarf spheroidal galaxy

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DOIResolve DOI: http://doi.org/10.1088/2041-8205/759/1/L12
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TypeArticle
Journal titleThe Astrophysical Journal Letters
ISSN2041-8205
Volume759
Issue1
Article numberL12
AbstractWe present a study of short-period, central helium-burning variable stars in the Local Group dwarf spheroidal galaxy LeoI, including 106 RR Lyrae stars and 51 Cepheids. So far, this is the largest sample of Cepheids and the largest Cepheids to RR Lyrae ratio found in such a kind of galaxy. Comparison with other Local Group dwarf spheroidals, Carina and Fornax, shows that the period distribution of RR Lyrae stars is quite similar, suggesting similar properties of the parent populations, whereas the Cepheid period distribution in LeoI peaks at longer periods (P ∼ 1.26days instead of ∼0.5days) and spans over a broader range, from 0.5 to 1.78days. Evolutionary and pulsation predictions indicate, assuming a mean metallicity peaked within -1.5 ≲ [Fe/H] ≲ -1.3, that the current sample of LeoI Cepheids traces a unique mix of anomalous Cepheids (blue extent of the red-clump, partially electron-degenerate central helium-burning stars) and short-period classical Cepheids (blue-loop, quiescent central helium-burning stars). Current evolutionary prescriptions also indicate that the transition mass between the two different groups of stars is M HeF ∼2.1 M ⊙, and it is constant for stars metal-poorer than [Fe/H] ∼-0.7. Finally, we briefly outline the different implications of the current findings on the star formation history of LeoI. © 2012. The American Astronomical Society. All rights reserved.
Publication date
LanguageEnglish
AffiliationNational Science Infrastructure; National Research Council Canada
Peer reviewedYes
NPARC number21270056
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Record identifier1f304354-70bd-4ae9-bade-9a0daddac470
Record created2013-12-16
Record modified2016-05-09
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