Variable stars in Local Group Galaxies: I. tracing the early chemical enrichment and radial gradients in the Sculptor dSph with RR Lyrae stars

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DOI	Resolve DOI: https://doi.org/10.1093/mnras/stv2014
Author	Search for: Martínez-vázquez, C. E.; Search for: Monelli, M.; Search for: Bono, G.; Search for: Stetson, P. B.¹ ; Search for: Ferraro, I.; Search for: Bernard, E. J.; Search for: Gallart, C.; Search for: Fiorentino, G.; Search for: Iannicola, G.; Search for: Udalski, A.
Name affiliation	National Research Council Canada. Herzberg Astronomy and Astrophysics
Format	Text
Type	Article
Journal title	Monthly Notices of the Royal Astronomical Society
ISSN	0035-8711 1365-2966
Volume	454
Issue	2
Pages	1509–1516
Subject	Kstars: variables: RR Lyrae; galaxies: evolution; galaxies: individual: Sculptor dSph; Local Group; galaxies: stellar content
Abstract	We identified and characterized the largest (536) RR Lyrae (RRL) sample in a Milky Way dSph satellite (Sculptor) based on optical photometry data collected over ∼24 years. The RRLs display a spread in V-magnitude (∼0.35 mag) which appears larger than photometric errors and the horizontal branch (HB) luminosity evolution of a mono-metallic population. Using several calibrations of two different reddening free and metal independent period–Wesenheit relations we provide a new distance estimate μ = 19.62 mag (σμ = 0.04 mag) that agrees well with literature estimates. We constrained the metallicity distribution of the old population, using the MI period–luminosity relation, and we found that it ranges from −2.3 to −1.5 dex. The current estimate is narrower than suggested by low and intermediate spectroscopy of RGBs (Δ [Fe/H]≤ 1.5). We also investigated the HB morphology as a function of the galactocentric distance. The HB in the innermost regions is dominated by red HB stars and by RRLs, consistent with a more metal-rich population, while in the outermost regions it is dominated by blue HB stars and RRLs typical of a metal-poor population. Our results suggest that fast chemical evolution occurred in Sculptor, and that the radial gradients were in place at an early epoch.
Publication date	2015-12-01
Publisher	Oxford University Press
Language	English
Peer reviewed	Yes
NPARC number	23001711
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Record identifier	918adfc7-d2b4-4cff-805f-986ed484d990
Record created	2017-03-21
Record modified	2019-03-12

Date modified:: 2019-05-24

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