The Acs lcid project. VII. the blue stragglers population in the isolated dsph galaxies Cetus and Tucana

M. Monelli; S. Cassisi; M. Mapelli; E. J. Bernard; A. Aparicio; E. D. Skillman; P. B. Stetson; C. Gallart; S. L. Hidalgo; L. Mayer; E. Tolstoy

doi:10.1088/0004-637X/744/2/157

The Acs lcid project. VII. the blue stragglers population in the isolated dsph galaxies Cetus and Tucana

M. Monelli, S. Cassisi, M. Mapelli, E. J. Bernard, A. Aparicio, E. D. Skillman, P. B. Stetson, C. Gallart, S. L. Hidalgo, L. Mayer, E. Tolstoy

Physics and Astronomy (Twin Cities)

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32 Scopus citations

Abstract

We present the first investigation of the Blue Straggler star (BSS) population in two isolated dwarf spheroidal galaxies of the Local Group, Cetus and Tucana. Deep Hubble Space Telescope/Advanced Camera for Surveys photometry allowed us to identify samples of 940 and 1214 candidates, respectively. The analysis of the star formation histories of the two galaxies suggests that both host a population of BSSs. Specifically, if the BSS candidates are interpreted as young main sequence stars, they do not conform to their galaxy's age-metallicity relationship. The analysis of the luminosity function and the radial distributions supports this conclusion, and suggests a non-collisional mechanism for the BSS formation, from the evolution of primordial binaries. This scenario is also supported by the results of new dynamical simulations presented here. Both galaxies coincide with the relationship between the BSS frequency and the absolute visual magnitude M_V found by Momany etal. If this relationship is confirmed by larger sample, then it could be a valuable tool to discriminate between the presence of BSSs and galaxies hosting truly young populations.

Original language	English (US)
Article number	157
Journal	Astrophysical Journal
Volume	744
Issue number	2
DOIs	https://doi.org/10.1088/0004-637X/744/2/157
State	Published - Jan 10 2012

Keywords

Galaxy: stellar content
Local Group
blue stragglers
galaxies: evolution
galaxies: individual (Cetus dSph, Tucana dSph)

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10.1088/0004-637X/744/2/157

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title = "The Acs lcid project. VII. the blue stragglers population in the isolated dsph galaxies Cetus and Tucana",

abstract = "We present the first investigation of the Blue Straggler star (BSS) population in two isolated dwarf spheroidal galaxies of the Local Group, Cetus and Tucana. Deep Hubble Space Telescope/Advanced Camera for Surveys photometry allowed us to identify samples of 940 and 1214 candidates, respectively. The analysis of the star formation histories of the two galaxies suggests that both host a population of BSSs. Specifically, if the BSS candidates are interpreted as young main sequence stars, they do not conform to their galaxy's age-metallicity relationship. The analysis of the luminosity function and the radial distributions supports this conclusion, and suggests a non-collisional mechanism for the BSS formation, from the evolution of primordial binaries. This scenario is also supported by the results of new dynamical simulations presented here. Both galaxies coincide with the relationship between the BSS frequency and the absolute visual magnitude MV found by Momany etal. If this relationship is confirmed by larger sample, then it could be a valuable tool to discriminate between the presence of BSSs and galaxies hosting truly young populations.",

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author = "M. Monelli and S. Cassisi and M. Mapelli and Bernard, {E. J.} and A. Aparicio and Skillman, {E. D.} and Stetson, {P. B.} and C. Gallart and Hidalgo, {S. L.} and L. Mayer and E. Tolstoy",

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doi = "10.1088/0004-637X/744/2/157",

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T1 - The Acs lcid project. VII. the blue stragglers population in the isolated dsph galaxies Cetus and Tucana

AU - Monelli, M.

AU - Cassisi, S.

AU - Mapelli, M.

AU - Bernard, E. J.

AU - Aparicio, A.

AU - Skillman, E. D.

AU - Stetson, P. B.

AU - Gallart, C.

AU - Hidalgo, S. L.

AU - Mayer, L.

AU - Tolstoy, E.

PY - 2012/1/10

Y1 - 2012/1/10

N2 - We present the first investigation of the Blue Straggler star (BSS) population in two isolated dwarf spheroidal galaxies of the Local Group, Cetus and Tucana. Deep Hubble Space Telescope/Advanced Camera for Surveys photometry allowed us to identify samples of 940 and 1214 candidates, respectively. The analysis of the star formation histories of the two galaxies suggests that both host a population of BSSs. Specifically, if the BSS candidates are interpreted as young main sequence stars, they do not conform to their galaxy's age-metallicity relationship. The analysis of the luminosity function and the radial distributions supports this conclusion, and suggests a non-collisional mechanism for the BSS formation, from the evolution of primordial binaries. This scenario is also supported by the results of new dynamical simulations presented here. Both galaxies coincide with the relationship between the BSS frequency and the absolute visual magnitude MV found by Momany etal. If this relationship is confirmed by larger sample, then it could be a valuable tool to discriminate between the presence of BSSs and galaxies hosting truly young populations.

AB - We present the first investigation of the Blue Straggler star (BSS) population in two isolated dwarf spheroidal galaxies of the Local Group, Cetus and Tucana. Deep Hubble Space Telescope/Advanced Camera for Surveys photometry allowed us to identify samples of 940 and 1214 candidates, respectively. The analysis of the star formation histories of the two galaxies suggests that both host a population of BSSs. Specifically, if the BSS candidates are interpreted as young main sequence stars, they do not conform to their galaxy's age-metallicity relationship. The analysis of the luminosity function and the radial distributions supports this conclusion, and suggests a non-collisional mechanism for the BSS formation, from the evolution of primordial binaries. This scenario is also supported by the results of new dynamical simulations presented here. Both galaxies coincide with the relationship between the BSS frequency and the absolute visual magnitude MV found by Momany etal. If this relationship is confirmed by larger sample, then it could be a valuable tool to discriminate between the presence of BSSs and galaxies hosting truly young populations.

KW - Galaxy: stellar content

KW - Local Group

KW - blue stragglers

KW - galaxies: evolution

KW - galaxies: individual (Cetus dSph, Tucana dSph)

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The Acs lcid project. VII. the blue stragglers population in the isolated dsph galaxies Cetus and Tucana

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