Discovery of an unusual dwarf galaxy in the outskirts of the milky way

M. J. Irwin, V. Belokurov, N. W. Evans, E. V. Ryan-Weber, J. T A De Jong, S. Koposov, D. B. Zucker, S. T. Hodgkin, G. Gilmore, P. Prema, L. Hebb, A. Begum, M. Fellhauer, P. C. Hewett, R. C. Kennicutt, M. I. Wilkinson, D. M. Bramich, S. Vidrih, H. W. Rix, T. C. BeersJ. C. Barentine, H. Brewington, M. Harvanek, J. Krzesinski, D. Long, A. Nitta, S. A. Snedden

Research output: Contribution to journalArticle

213 Citations (Scopus)

Abstract

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 ∼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 ∼200 Myr. There is a compact cloud of neutral hydrogen with mass ∼105 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.

Original languageEnglish
JournalAstrophysical Journal
Volume656
Issue number1 II
DOIs
Publication statusPublished - 10 Feb 2007
Externally publishedYes

Fingerprint

color-magnitude diagram
dwarf galaxies
diagram
luminosity
Phoenix (AZ)
blue stars
young population
massive stars
radial velocity
metallicity
star formation
hydrogen
galaxies
young

Keywords

  • Galaxies: dwarf
  • Galaxies: individual (Leo)
  • Local group

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Irwin, M. J., Belokurov, V., Evans, N. W., Ryan-Weber, E. V., De Jong, J. T. A., Koposov, S., ... Snedden, S. A. (2007). Discovery of an unusual dwarf galaxy in the outskirts of the milky way. Astrophysical Journal, 656(1 II). https://doi.org/10.1086/512183

Discovery of an unusual dwarf galaxy in the outskirts of the milky way. / 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.; 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.

In: Astrophysical Journal, Vol. 656, No. 1 II, 10.02.2007.

Research output: Contribution to journalArticle

Irwin, MJ, Belokurov, V, Evans, NW, Ryan-Weber, EV, De Jong, JTA, Koposov, S, Zucker, DB, Hodgkin, ST, Gilmore, G, Prema, P, Hebb, L, Begum, A, Fellhauer, M, Hewett, PC, Kennicutt, RC, Wilkinson, MI, Bramich, DM, Vidrih, S, Rix, HW, Beers, TC, Barentine, JC, Brewington, H, Harvanek, M, Krzesinski, J, Long, D, Nitta, A & Snedden, SA 2007, 'Discovery of an unusual dwarf galaxy in the outskirts of the milky way', Astrophysical Journal, vol. 656, no. 1 II. https://doi.org/10.1086/512183
Irwin MJ, Belokurov V, Evans NW, Ryan-Weber EV, De Jong JTA, Koposov S et al. Discovery of an unusual dwarf galaxy in the outskirts of the milky way. Astrophysical Journal. 2007 Feb 10;656(1 II). https://doi.org/10.1086/512183
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. ; 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. / Discovery of an unusual dwarf galaxy in the outskirts of the milky way. In: Astrophysical Journal. 2007 ; Vol. 656, No. 1 II.
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