Probing the early chemical evolution of the Sculptor dSph with purely old stellar tracers
Date Issued
2016
Author(s)
Martínez-Vázquez, C. E.
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Gallart, C.
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Bernard, E. J.
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Stetson, P. B.
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Walker, A. R.
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Abstract
We present the metallicity distribution of a sample of 471 RR Lyrae (RRL) stars in the Sculptor dSph, obtained from the I-band period-luminosity relation. It is the first time that the early chemical evolution of a dwarf galaxy is characterized in such a detailed and quantitative way, using photometric data alone. We find a broad metallicity distribution (full width at half-maximum equals to 0.8 dex) that is peaked at [Fe/H] ≃ -1.90 dex, in excellent agreement with literature values obtained from spectroscopic data. Moreover, we are able to directly trace the metallicity gradient out to a radius of ∼55 arcmin. We find that in the outer regions (r > ∼32 arcmin) the slope of the metallicity gradient from the RRLs (-0.025 dex arcmin-1) is comparable to the literature values based on red giant (RG) stars. However, in the central part of Sculptor, we do not observe the latter gradients. This suggests that there is a more metal-rich and/or younger population in Sculptor that does not produce RRLs. This scenario is strengthened by the observation of a metal-rich peak in the metallicity distribution of RG stars by other authors, which is not present in the metallicity distribution of the RRLs within the same central area.
Volume
461
Issue
1
Start page
L41
Issn Identifier
0035-8711
Ads BibCode
2016MNRAS.461L..41M
Rights
open.access
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