2006ApJ...650L..41Z

Query : 2006ApJ...650L..41Z

2006ApJ...650L..41Z - Astrophys. J., 650, L41-L44 (2006/October-2)

A curious Milky Way satellite in Ursa Major.

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. and SNEDDEN S.A.

Abstract (from CDS):

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 ∼250x125 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.

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Journal keyword(s): Galaxies: Dwarf - galaxies: individual (Ursa Major II) - Galaxies: Local Group

Simbad objects: 14

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Number of rows : 14
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NAME Andromeda IX G 00 52 53.0 +43 11 45     16.3     ~ 176 1
2 NAME Andromeda X G 01 06 33.70 +44 48 15.8     16.6     ~ 125 1
3 Cl Pal 1 GlC 03 33 20.04 +79 34 51.8   17.2       ~ 267 1
4 NAME HVC Complex A HVC 08 36 +64.4           ~ 138 0
5 NAME UMa II Galaxy G 08 51 30.0 +63 07 48     13.3     ~ 410 0
6 NAME UMa I Galaxy G 10 34 52.80 +51 55 12.0     14.4     ~ 355 1
7 NAME Willman 1 G 10 49 21.0 +51 03 00     15.2     ~ 345 0
8 Cl Ruprecht 106 GlC 12 38 40.20 -51 09 01.0           ~ 413 0
9 NAME NGP reg 12 51 26.275 +27 07 41.70           ~ 1274 0
10 NAME CVn I dSph G 13 28 03.5 +33 33 21     13.1     ~ 352 1
11 NAME Bootes Dwarf Spheroidal Galaxy G 14 00 00.0 +14 30 00     12.8     ~ 491 0
12 Z 318-18 G 15 09 08.0 +67 13 21   13.60 10.6     ~ 1459 0
13 NAME Orphan Stream St* 19 09 -23.           ~ 281 0
14 NAME Local Group GrG ~ ~           ~ 9325 0

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