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Hydra II: A Faint and Compact Milky Way Dwarf Galaxy Found in the Survey of the Magellanic Stellar History

Martin, NF, Nidever, DL, Besla, G, Olsen, K, Walker, AR, Vivas, AK, Gruendl, RA, Kaleida, CC, Muñoz, RR, Blum, RD, Saha, A, Conn, BC, Bell, EF, Chu, YH, Cioni, MRL, De Boer, TJL, Gallart, C, Jin, S, Kunder, A, Majewski, SR, Martinez-Delgado, D, Monachesi, A, Monelli, M, Monteagudo, L, Noël, NED, Olszewski, EW, Stringfellow, GS, Van Der Marel, RP and Zaritsky, D (2015) Hydra II: A Faint and Compact Milky Way Dwarf Galaxy Found in the Survey of the Magellanic Stellar History Astrophysical Journal Letters, 804 (1).

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Abstract

© 2015. The American Astronomical Society. All rights reserved.We present the discovery of a new dwarf galaxy, Hydra II, found serendipitously within the data from the ongoing Survey of the Magellanic Stellar History conducted with the Dark Energy Camera on the Blanco 4 m Telescope. The new satellite is compact (rh = 68 ± 11 pc) and faint (MV = -4.8 ± 0.3), but well within the realm of dwarf galaxies. The stellar distribution of Hydra II in the color-magnitude diagram is well-described by a metal-poor ([Fe/H] = -2.2) and old (13 Gyr) isochrone and shows a distinct blue horizontal branch, some possible red clump stars, and faint stars that are suggestive of blue stragglers. At a heliocentric distance of 134 ± 10 kpc, Hydra II is located in a region of the Galactic halo that models have suggested may host material from the leading arm of the Magellanic Stream. A comparison with N-body simulations hints that the new dwarf galaxy could be or could have been a satellite of the Magellanic Clouds.

Item Type: Article
Subjects : Physics
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
AuthorsEmailORCID
Martin, NFUNSPECIFIEDUNSPECIFIED
Nidever, DLUNSPECIFIEDUNSPECIFIED
Besla, GUNSPECIFIEDUNSPECIFIED
Olsen, KUNSPECIFIEDUNSPECIFIED
Walker, ARUNSPECIFIEDUNSPECIFIED
Vivas, AKUNSPECIFIEDUNSPECIFIED
Gruendl, RAUNSPECIFIEDUNSPECIFIED
Kaleida, CCUNSPECIFIEDUNSPECIFIED
Muñoz, RRUNSPECIFIEDUNSPECIFIED
Blum, RDUNSPECIFIEDUNSPECIFIED
Saha, AUNSPECIFIEDUNSPECIFIED
Conn, BCUNSPECIFIEDUNSPECIFIED
Bell, EFUNSPECIFIEDUNSPECIFIED
Chu, YHUNSPECIFIEDUNSPECIFIED
Cioni, MRLUNSPECIFIEDUNSPECIFIED
De Boer, TJLUNSPECIFIEDUNSPECIFIED
Gallart, CUNSPECIFIEDUNSPECIFIED
Jin, SUNSPECIFIEDUNSPECIFIED
Kunder, AUNSPECIFIEDUNSPECIFIED
Majewski, SRUNSPECIFIEDUNSPECIFIED
Martinez-Delgado, DUNSPECIFIEDUNSPECIFIED
Monachesi, AUNSPECIFIEDUNSPECIFIED
Monelli, MUNSPECIFIEDUNSPECIFIED
Monteagudo, LUNSPECIFIEDUNSPECIFIED
Noël, NEDUNSPECIFIEDUNSPECIFIED
Olszewski, EWUNSPECIFIEDUNSPECIFIED
Stringfellow, GSUNSPECIFIEDUNSPECIFIED
Van Der Marel, RPUNSPECIFIEDUNSPECIFIED
Zaritsky, DUNSPECIFIEDUNSPECIFIED
Date : 1 May 2015
Identification Number : https://doi.org/10.1088/2041-8205/804/1/L5
Copyright Disclaimer : © 2015. The American Astronomical Society. All rights reserved.
Uncontrolled Keywords : Galaxies: individual (Hydra II) ; Local Group; Magellanic Clouds
Depositing User : Symplectic Elements
Date Deposited : 30 Mar 2017 14:50
Last Modified : 30 Mar 2017 14:50
URI: http://epubs.surrey.ac.uk/id/eprint/813861

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