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The ISLAnds Project. III. Variable stars in six Andromeda dwarf spheroidal galaxies

Citation

Martinez-Vazquez, CE and Monelli, M and Bernard, EJ and Gallart, C and Stetson, PB and Skillman, ED and Bono, G and Cassisi, S and Fiorentino, G and McQuinn, KBW and Cole, AA and McConnachie, AW and Martin, NF and Dolphin, AE and Boylan-Kolchin, M and Aparicio, A and Hidalgo, SL and Weisz, DR, The ISLAnds Project. III. Variable stars in six Andromeda dwarf spheroidal galaxies, Astrophysical Journal, 850, (2) Article 137. ISSN 0004-637X (2017) [Refereed Article]


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Copyright 2017 The American Astronomical Society

DOI: doi:10.3847/1538-4357/aa9381

Abstract

We present a census of variable stars in six M31 dwarf spheroidal satellites observed with the Hubble Space Telescope. We detect 870 RR Lyrae (RRL) stars in the fields of And I (296), II (251), III (111), XV (117), XVI (8), and XXVIII (87). We also detect a total of 15 Anomalous Cepheids, three eclipsing binaries, and seven field RRL stars compatible with being members of the M31 halo or the Giant Stellar Stream. We derive robust and homogeneous distances to the six galaxies using different methods based on the properties of the RRL stars. Working with the up-to-date set of Period-Wesenheit (I, BI) relations published by Marconi et al., we obtain distance moduli of μ 0 = [24.49, 24.16, 24.36, 24.42, 23.70, 24.43] mag (respectively), with systematic uncertainties of 0.08 mag and statistical uncertainties <0.11 mag. We have considered an enlarged sample of 16 M31 satellites with published variability studies, and compared their pulsational observables (e.g., periods and amplitudes) with those of 15 Milky Way satellites for which similar data are available. The properties of the (strictly old) RRL in both satellite systems do not show any significant difference. In particular, we found a strikingly similar correlation between the mean period distribution of the fundamental RRL pulsators (RRab) and the mean metallicities of the galaxies. This indicates that the old RRL progenitors were similar at the early stage in the two environments, suggesting very similar characteristics for the earliest stages of evolution of both satellite systems.

Item Details

Item Type:Refereed Article
Keywords:galaxies: dwarf, galaxies: stellar content, stars: variable
Research Division:Physical Sciences
Research Group:Astronomical and Space Sciences
Research Field:Galactic Astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Physical Sciences
Author:Cole, AA (Associate Professor Andrew Cole)
ID Code:123471
Year Published:2017
Deposited By:Mathematics and Physics
Deposited On:2018-01-09
Last Modified:2018-04-27
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