2008ApJ...685L..43K

Query : 2008ApJ...685L..43K

2008ApJ...685L..43K - Astrophys. J., 685, L43-L46 (2008/September-3)

Uncovering extremely metal-poor stars in the Milky Way's ultrafaint dwarf spheroidal satellite galaxies.

KIRBY E.N., SIMON J.D., GEHA M., GUHATHAKURTA P. and FREBEL A.

Abstract (from CDS):

We present new metallicity measurements for 298 individual red giant branch stars in eight of the least luminous dwarf spheroidal galaxies (dSphs) in the Milky Way (MW) system. Our technique is based on medium-resolution Keck DEIMOS spectroscopy coupled with spectral synthesis. We present the first spectroscopic metallicities at [Fe/H]←3.0 of stars in a dwarf galaxy, with individual stellar metallicities as low as [Fe/H]=-3.3. Because our [Fe/H] measurements are not tied to empirical metallicity calibrators and are sensitive to arbitrarily low metallicities, we are able to probe this extremely metal-poor regime accurately. The metallicity distribution of stars in these dSphs is similar to the MW halo at the metal-poor end. We also demonstrate that the luminosity-metallicity relation previously seen in more luminous dSph galaxies (MV=-13.4 to -8.8) extends smoothly down to an absolute magnitude of MV=-3.7. The discovery of extremely metal-poor stars in dSphs lends support to the ΛCDM galaxy assembly paradigm wherein dwarf galaxies dissolve to form the stellar halo of the MW.

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Journal keyword(s): Galaxies: Abundances - Galaxies: Dwarf

Simbad objects: 18

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Number of rows : 18
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 M 31 AGN 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 13622 1
2 MCG-06-07-001 G 02 39 59.3 -34 26 57   9.02 7.4     ~ 1894 1
3 ESO 206-20A G 06 41 36.7 -50 57 58   22.14 11.0 19.47   ~ 1190 0
4 NAME UMa II Galaxy G 08 51 30.0 +63 07 48     13.3     ~ 410 0
5 NAME Leo T G 09 34 53.4 +17 03 05     15.1     ~ 434 0
6 NAME Segue 1 G 10 07 03.2 +16 04 25     15.3     ~ 517 1
7 NAME Sextans dSph LSB 10 13 02.9 -01 36 53   12 10.4     ~ 921 0
8 NAME UMa I Galaxy G 10 34 52.80 +51 55 12.0     14.4     ~ 355 1
9 NAME Willman 1 G 10 49 21.0 +51 03 00     15.2     ~ 345 0
10 NAME UMa Region reg 11 00 +50.0           ~ 333 0
11 NAME Leo IV LSB 11 32 57.0 -00 32 00     15.1     ~ 419 1
12 NAME Coma Dwarf Galaxy G 12 26 59.0 +23 54 15     14.1     ~ 482 1
13 NAME CVn II dSph G 12 57 09.6 +34 19 12     16.1     ~ 287 2
14 NAME CVn I dSph G 13 28 03.5 +33 33 21     13.1     ~ 352 1
15 NAME Bootes II G 13 58 00.0 +12 51 00     15.4     ~ 269 0
16 ACO 2151 ClG 16 05 15.0 +17 44 55           ~ 594 3
17 NAME Hercules Dwarf Galaxy G 16 31 02.0 +12 47 30     14.0     ~ 379 1
18 M 15 GlC 21 29 58.33 +12 10 01.2           ~ 3274 0

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