2004A&A...414..503B


Query : 2004A&A...414..503B

2004A&A...414..503B - Astronomy and Astrophysics, volume 414, 503-514 (2004/2-1)

The Sgr dSph hosts a metal-rich population.

BONIFACIO P., SBORDONE L., MARCONI G., PASQUINI L. and HILL V.

Abstract (from CDS):

We report on abundances of O, Mg, Si, Ca and Fe for 10 giants in the Sgr dwarf spheroidal derived from high resolution spectra obtained with UVES at the 8.2 m Kueyen-VLT telescope. The iron abundance spans the range -0.8≲[Fe/H]≲0.0 and the dominant population is relatively metal-rich with [Fe/H]~-0.25. The α/Fe ratios are slightly subsolar, even at the lowest observed metallicities suggesting a slow or bursting star formation rate. From our sample of 12 giants (including the two observed by Bonifacio et al. (2000A&A...359..663B) we conclude that a substantial metal rich population exists in Sgr, which dominates the sample. The spectroscopic metallicities allow one to break the age-metallicity degeneracy in the interpretation of the colour-magnitude diagram (CMD). Comparison of isochrones of appropriate metallicity with the observed CMD suggests an age of 1 Gyr or younger, for the dominant Sgr population sampled by us. We argue that the observations support a star formation that is triggered by the passage of Sgr through the Galactic disc, both in Sgr and in the disc. This scenario has also the virtue of explaining the mysterious ``bulge C stars'' as disc stars formed in this event. The interaction of Sgr with the Milky Way is likely to have played a major role in its evolution.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: atmospheres - galaxies: abundances - galaxies: evolution - galaxies: dwarf - galaxies: individual: Sgr dSph

VizieR on-line data: <Available at CDS (J/A+A/414/503): table1.dat table3.dat>

Simbad objects: 20

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Number of rows : 20
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 NGC 104 GlC 00 24 05.359 -72 04 53.20   5.78 4.09     ~ 3737 0
2 HD 27317 ** 04 16 44.68029 -44 17 37.7911   9.475 9.165 9.613   F6V 10 0
3 * del Tau SB* 04 22 56.0951595936 +17 32 33.049802364 5.56 4.74 3.76 5.56   G9.5IIICN0.5 508 0
4 Cl Melotte 25 OpC 04 29 47 +16 56.9           ~ 2861 0
5 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16155 1
6 [MBC98a] Sgr1 894 * 18 53 36.8601808704 -30 29 54.300971544     18.34     ~ 5 0
7 [MBC98a] Sgr1 709 * 18 53 38.7508616520 -30 29 28.775530500     18.09     ~ 5 0
8 [MBC98a] Sgr1 656 * 18 53 45.7395179424 -30 25 57.496868436     18.04     ~ 5 0
9 [MBC98a] Sgr1 628 * 18 53 47.9306307168 -30 26 14.658690876     18.00     ~ 5 0
10 [MBC98a] Sgr1 717 * 18 53 48.05 -30 29 38.1     18.10     ~ 4 0
11 [BHM2000] 143 * 18 53 48.13 -30 32 00.8     18.15     ~ 7 0
12 [BHM2000] 139 * 18 53 48.6159120264 -30 30 48.951274248     18.33     ~ 7 0
13 [MBC98a] Sgr1 432 * 18 53 50.7810451872 -30 27 27.498335832     17.55     ~ 5 0
14 [MBC98a] Sgr1 635 * 18 53 51.0805040071 -30 26 48.531269445     18.01     ~ 5 0
15 [MBC98a] Sgr1 927 * 18 53 51.7148503867 -30 26 50.872598680     18.39     ~ 5 0
16 [MBC98a] Sgr1 716 * 18 53 52.9946099088 -30 27 12.973805856     18.10     ~ 5 0
17 [MBC98a] Sgr1 867 * 18 53 53.0507039172 -30 27 29.354658232     18.30     ~ 5 0
18 NAME SDG G 18 55 03.1 -30 28 42   4.5 3.6     ~ 1970 2
19 M 54 GlC 18 55 03.33 -30 28 47.5           ~ 1003 0
20 M 2 GlC 21 33 27.02 -00 49 23.7     6.25     ~ 968 1

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2022.08.10-18:57:05

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