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ID:
308510.0,
MPI für Astronomie / Publikationen_mpia |
A curious Milky Way satellite in Ursa Major |
Authors: | Zucker, D. B.; Belokurov, V.; Evans, N. W.; Kleyna, J. T.; Irwin, M. J.; Wilkinson, M. I.; Fellhauer, M.; Bramich, D. M.; Gilmore, G.; Newberg, H. J.; Yanny, B.; Smith, J. A.; Hewett, P. C.; Bell, E. F.; Rix, H. W.; Gnedin, O. Y.; Vidrih, S.; Wyse, R. F. G.; Willman, B.; Grebel, E. K.; Schneider, D. P.; Beers, T. C.; Kniazev, A. Y.; Barentine, J. C.; Brewington, H.; Brinkmann, J.; Harvanek, M.; Kleinman, S. J.; Krzesinski, J.; Long, D.; Nitta, A.; Snedden, S. A. | Date of Publication (YYYY-MM-DD): | 2006 | Journal Abbrev.: | The Astrophysical Journal | Volume: | 650 | Start Page: | L41 | End Page: | L44 | Audience: | Not Specified | Abstract / Description: | In this Letter, we study a localized stellar overdensity in the constellation of Ursa Major, first identified in Sloan Digital Sky Survey (SDSS) data and subsequently followed up with Subaru imaging. Its color-magnitude diagram (CMD) shows a well-defined subgiant branch, main sequence, and turnoff, from which we estimate a distance of ~30 kpc and a projected size of ~250×125 pc2. The CMD suggests a composite population with some range in metallicity and/or age. Based on its extent and stellar population, we argue that this is a previously unknown satellite galaxy of the Milky Way, hereby named Ursa Major II (UMa II) after its constellation. Using SDSS data, we find an absolute magnitude of MV~-3.8, which would make it the faintest known satellite galaxy. UMa II's isophotes are irregular and distorted with evidence for multiple concentrations; this suggests that the satellite is in the process of disruption. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. | Free Keywords: | Galaxies: Dwarf; galaxies: individual (Ursa Major II); Galaxies: Local Group | External Publication Status: | published | Document Type: | Article |
Communicated by: | N. N. | Affiliations: | MPI für Astronomie | Identifiers: | URL:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bi...
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