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. Beers; J. C. Barentine; H. Brewington; M. Harvanek; J. Krzesinski; D. Long; A. Nitta; S. A. Snedden

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

School of Physics and Astronomy

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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 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.

Original language	English
Number of pages	4
Journal	Astrophysical Journal Letters
Volume	656
Publication status	Published - 10 Feb 2007

Keywords

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

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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., ... Snedden, S. A. (2007). Discovery of an unusual dwarf galaxy in the outskirts of the Milky Way. Astrophysical Journal Letters, 656.

@article{fc12b1da0a394cbb8607ac2f30e1ef30,

title = "Discovery of an unusual dwarf galaxy in the outskirts of the Milky Way",

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 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.",

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

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

year = "2007",

month = feb,

day = "10",

language = "English",

volume = "656",

journal = "Astrophysical Journal Letters",

issn = "2041-8205",

publisher = "American Astronomical Society",

}

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, H-W, 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 Letters, vol. 656.

TY - JOUR

T1 - Discovery of an unusual dwarf galaxy in the outskirts of the Milky Way

AU - Irwin, M. J.

AU - Belokurov, V.

AU - Evans, N. W.

AU - Ryan-Weber, E. V.

AU - de Jong, J. T. A.

AU - Koposov, S.

AU - Zucker, D. B.

AU - Hodgkin, S. T.

AU - Gilmore, G.

AU - Prema, P.

AU - Hebb, L.

AU - Begum, A.

AU - Fellhauer, M.

AU - Hewett, P. C.

AU - Kennicutt, R. C.

AU - Wilkinson, M. I.

AU - Bramich, D. M.

AU - Vidrih, S.

AU - Rix, H. -W.

AU - Beers, T. C.

AU - Barentine, J. C.

AU - Brewington, H.

AU - Harvanek, M.

AU - Krzesinski, J.

AU - Long, D.

AU - Nitta, A.

AU - Snedden, S. A.

PY - 2007/2/10

Y1 - 2007/2/10

N2 - 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.

AB - 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.

KW - galaxies : dwarf

KW - galaxies : individual (Leo)

KW - Local Group

KW - DIGITAL SKY SURVEY

KW - LOCAL GROUP

KW - DATA RELEASE

KW - URSA-MAJOR

KW - SYSTEM

KW - SATELLITE

KW - CALIBRATION

KW - CAMERA

KW - FIELD

UR - https://www.scopus.com/pages/publications/33847397895

M3 - Article

SN - 2041-8205

VL - 656

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

ER -

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

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Keywords

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