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Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-30871

Belokurov, V; Walker, M G; Evans, N W; Gilmore, G; Irwin, M J; Mateo, M; Mayer, L; Olszewski, E; Bechtold, J; Pickering, T (2009). The discovery of Segue 2: a prototype of the population of satellites of satellites. Monthly Notices of the Royal Astronomical Society, 397(4):1748-1755.

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We announce the discovery of a new Milky Way satellite Segue 2 found in the data of the Sloan Extension for Galactic Understanding and Exploration (SEGUE). We followed this up with deeper imaging and spectroscopy on the Multiple Mirror Telescope (MMT). From this, we derive a luminosity of Mv=−2.5 , a half-light radius of 34 pc and a systemic velocity of ∼−40 km s−1 . Our data also provide evidence for a stream around Segue 2 at a similar heliocentric velocity, and the SEGUE data show that it is also present in neighbouring fields. We resolve the velocity dispersion of Segue 2 as 3.4 km s−1 and the possible stream as ∼7 km s−1 . This object shows points of comparison with other recent discoveries, Segue 1, Boo II and Coma. We speculate that all four objects may be representatives of a population of satellites of satellites – survivors of accretion events that destroyed their larger but less dense parents. They are likely to have formed at redshifts z > 10 and are good candidates for fossils of the reionization epoch.


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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute for Computational Science
Dewey Decimal Classification:530 Physics
Uncontrolled Keywords:galaxies: dwarf; galaxies: individual: Segue 2; Local Group
Date:August 2009
Deposited On:25 Feb 2010 19:49
Last Modified:05 Apr 2016 13:56
Funders:Alfred P. Sloan Foundation
Additional Information:The attached file is a preprint (accepted version) of an article published in Monthly Notices of the Royal Astronomical Society. The definitive version is available at www3.interscience.wiley.com
Publisher DOI:10.1111/j.1365-2966.2009.15106.x
Related URLs:http://arxiv.org/abs/0903.0818

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