Hydra II: a faint and compact milky way dwarf galaxy found in the survey of the magellanic stellar history
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 (r_h = 68 ± 11 pc) and faint (M_V = -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 |
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Additional information | Date of Acceptance: 31/03/2015 |
Keywords | galaxies: individual (hydra ii), local group, magellanic clouds |
Date Deposited | 15 May 2025 12:55 |
Last Modified | 31 May 2025 00:00 |
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