학술논문
Discovery of an Unusual Dwarf Galaxy in the Outskirts of the Milky Way
Document Type
Working Paper
Author
Irwin, M. J.; Belokurov, V.; Evans, N. W.; Ryan-Weber, E. V.; de Jong, J. T. A.; Koposov, S.; Zucker, D. B.; Hodgkin, S. T.; Gilmore, G.; Prema, P.; Hebb, L.; Begum, A.; Fellhauer, M.; Hewett, P. C.; Kennicutt, Jr., R. C.; Wilkinson, M. I.; Bramich, D. M.; Vidrih, S.; Rix, H. -W.; Beers, T. C.; Barentine, J. C.; Brewington, H.; Harvanek, M.; Krzesinski, J.; Long, D.; Nitta, A.; Snedden, S. A.
Source
Astrophys.J.656:L13-L16,2007
Subject
Language
Abstract
In this Letter, we announce the discovery of a new dwarf galaxy, Leo T, in the Local Group. It was found as a stellar overdensity in the Sloan Digital Sky Survey Data Release 5 (SDSS DR5). The color-magnitude diagram of Leo T shows two well-defined features, which we interpret as a red giant branch and a sequence of young, massive stars. As judged from fits to the color-magnitude diagram, it lies at a distance of about 420 kpc and has an intermediate-age stellar population with a metallicity of [Fe/H]= -1.6, together with a young population of blue stars of age of 200 Myr. There is a compact cloud of neutral hydrogen with mass roughly 10^5 solar masses and radial velocity 35 km/s coincident with the object visible in the HIPASS channel maps. Leo T is the smallest, lowest luminosity galaxy found to date with recent star-formation. It appears to be a transition object similar to, but much lower luminosity than, the Phoenix dwarf.
Comment: Ap J (Letters) in press, the subject of an SDSS press release today
Comment: Ap J (Letters) in press, the subject of an SDSS press release today