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Title: Kinematically Cold Populations at Large Radii in the Draco and Ursa Minor Dwarf Spheroidal Galaxies
Authors: Wilkinson, M. I.
Kleyna, J. T.
Evans, N. W.
Gilmore, G. F.
Irwin, M. J.
Grebel, E. K.
First Published: 12-Jul-2004
Publisher: American Astronomical Society, IOP Publishing
Citation: Astrophysical Journal Letters, 2004, 611 (1), pp.21-24
Abstract: We present projected velocity dispersion profiles for the Draco and Ursa Minor (UMi) dwarf spheroidal galaxies based on 207 and 162 discrete stellar velocities, respectively. Both profiles show a sharp decline in the velocity dispersion outside ~30' (Draco) and ~40' (UMi). New deep photometry of Draco reveals a break in the light profile at ~25'. These data imply the existence of a kinematically cold population in the outer parts of both galaxies. Possible explanations of both the photometric and the kinematic data in terms of both equilibrium and nonequilibrium models are discussed in detail. We conclude that these data challenge the picture of dwarf spheroidal galaxies as simple, isolated stellar systems.
DOI Link: 10.1086/423619
ISSN: 0004-6388
Type: Article
Rights: Archived with reference to SHERPA/RoMEO and publisher website. © 2004. The American Astronomical Society. All rights reserved.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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