Discovery of an unusual dwarf galaxy in the outskirts of the Milky Way

被引：224

作者：

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, R. C., Jr.

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.

机构：

[1] Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England

[2] Max Planck Inst Astron, D-69117 Heidelberg, Germany

[3] Univ St Andrews, Sch Phys & Astron, N Haug, Scotland

[4] Michigan State Univ, Dept Phys & Astron, E Lansing, MI 48824 USA

[5] Apache Point Observ, Sunspot, NM USA

[6] Cracow Pedag Univ, Mt Suhora Observ, Krakow, Poland

[7] Gemini Observ, Hilo, HI USA

来源：

ASTROPHYSICAL JOURNAL | 2007年 / 656卷 / 01期

关键词：

galaxies : dwarf; galaxies : individual (Leo); Local Group; DIGITAL SKY SURVEY; LOCAL GROUP; DATA RELEASE; URSA-MAJOR; SYSTEM; SATELLITE; CALIBRATION; CAMERA; FIELD;

D O I：

10.1086/512183

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

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 similar to 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 similar to 200 Myr. There is a compact cloud of neutral hydrogen with mass similar to 10(5) M-. and radial velocity + 35 km s(-1) 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.

引用

页码：L13 / L16

页数：4

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