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The ISLANDS project. I. Andromeda XVI, an extremely low mass galaxy not quenched by reionization

Citation

Monelli, M and Martinez-Vazquez, CE and Bernard, EJ and Gallart, C and Skillman, ED and Weisz, DR and Dolphin, AE and Hidalgo, SL and Cole, AA and Martin, NF and Aparicio, A and Cassisi, S and Boylan-Kolchin, M and Mayer, L and McConnachie, A and McQuinn, KBW and Navarro, JF, The ISLANDS project. I. Andromeda XVI, an extremely low mass galaxy not quenched by reionization, Astrophysical Journal, 819, (2) Article 147. ISSN 0004-637X (2016) [Refereed Article]


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© 2016. The American Astronomical Society. All rights reserved.

DOI: doi:10.3847/0004-637X/819/2/147

Abstract

Based on data aquired in 13 orbits of Hubble Space Telescope time, we present a detailed evolutionary history of the M31 dSph satellite Andromeda XVI, including its lifetime star formation history (SFH), the spatial distribution of its stellar populations, and the properties of its variable stars. And XVI is characterized by prolonged star formation activity from the oldest epochs until star formation was quenched ~6 Gyr ago, and, notably, only half of the mass in stars of And XVI was in place 10 Gyr ago. And XVI appears to be a low-mass galaxy for which the early quenching by either reionization or starburst feedback seems highly unlikely, and thus it is most likely due to an environmental effect (e.g., an interaction), possibly connected to a late infall in the densest regions of the Local Group. Studying the SFH as a function of galactocentric radius, we detect a mild gradient in the SFH: the star formation activity between 6 and 8 Gyr ago is significantly stronger in the central regions than in the external regions, although the quenching age appears to be the same, within 1 Gyr. We also report the discovery of nine RR Lyrae (RRL) stars, eight of which belong to And XVI. The RRL stars allow a new estimate of the distance, (m − M)0 = 23.72 ± 0.09 mag, which is marginally larger than previous estimates based on the tip of the red giant branch.

Item Details

Item Type:Refereed Article
Keywords:galaxies: dwarf, galaxies: evolution, galaxies: individual (Andromeda XVI), Local Group, stars: variables: RR Lyrae
Research Division:Physical Sciences
Research Group:Astronomical and Space Sciences
Research Field:Cosmology and Extragalactic Astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Physical Sciences
Author:Cole, AA (Dr Andrew Cole)
ID Code:107647
Year Published:2016
Web of Science® Times Cited:8
Deposited By:Mathematics and Physics
Deposited On:2016-03-21
Last Modified:2017-11-01
Downloads:183 View Download Statistics

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