2007A&A...466..181C


C.D.S. - SIMBAD4 rel 1.7 - 2020.11.28CET21:58:35

2007A&A...466..181C - Astronomy and Astrophysics, volume 466, 181-189 (2007/4-4)

Whiting 1: the youngest globular cluster associated with the Sagittarius dwarf spheroidal galaxy.

CARRARO G., ZINN R. and MONI BIDIN C.

Abstract (from CDS):

Recently, Carraro (2005ApJ...621L..61C) drew attention to the remarkable star cluster Whiting 1 by showing that it lies about 40kpc from the Sun and is therefore unquestionably a member of the Galactic halo (b=-60.6deg). Its Color Magnitude Diagram (CMD) indicated that Whiting 1 is very young (∼5Gyr) for a globular cluster. It is very likely that Whiting 1 originated in a dwarf galaxy that has since been disrupted by the Milky Way. The main goals of this investigation were to constrain better the age, metallicity, and distance of Whiting 1 and to assess whether it belongs to a stellar stream from the Sagittarius dwarf spheroidal galaxy (Sgr dSph). Deep CCD photometry in the BVI pass-bands obtained with the VLT is used to improve the quality of the CMD and to determine the cluster's luminosity function and surface density profile. High-resolution spectrograms obtained with Magellan are used to measure the cluster's radial velocity and to place limits on its possible metallicity. The measurements of distance and radial velocity are used to test the cluster's membership in the stellar streams from the Sgr dSph. From our CMD of Whiting 1, we derive new estimates for the cluster's age (6.5+1.0–0.5Gyr), metallicity (Z=0.004±0.001, [Fe/H]=-0.65), and distance (29.4+1.8–2.0kpc). From echelle spectrograms of three stars, we obtain -130.6±1.8km/s for the cluster's radial velocity and show from measurements of two infra-red CaII lines that the [Fe/H] of the cluster probably lies in the range -1.1 to -0.4. Both the luminosity function and the surface density profile suggest that the cluster has undergone tidal stripping by the Milky Way. We demonstrate that the position of Whiting 1 on the sky, its distance from the Sun, and its radial velocity are identical to within the errors of both the theoretical predictions of the trailing stream of stars from the Sgr dSph galaxy and the previous observations of the M giant stars that delineate the streams. With the addition of Whiting 1, there is now strong evidence that 6 globular clusters formed within the Sgr dSph. Whiting 1 is particularly interesting because it is the youngest and among the most metal rich. The relatively young age of Whiting 1 demonstrates that this dwarf galaxy was able to form star clusters for a period of at least 6 Gyr, and the age and metallicity of Whiting 1 are consistent with the age-metallicity relationship in the main body of the Sgr dSph. The presence now of Whiting 1 in the Galactic halo provides additional support for the view that the young halo clusters originated in dwarf galaxies that have been accreted by the Milky Way.

Abstract Copyright:

Journal keyword(s): Galaxy: halo - Galaxy: evolution - Galaxy: globular clusters: general - Galaxy: globular clusters: Sgr dSph

Nomenclature: Catalog: [CZM2007] NNNN N=952 among (Nos 1-1649).

Status at CDS : All or part of tables of objects will not be ingested in SIMBAD.

Simbad objects: 26

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Number of rows : 26

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NGC 104 GlC 00 24 05.359 -72 04 53.20   5.78 4.09     ~ 3584 0
2 NGC 288 GlC 00 52 45.24 -26 34 57.4   10 8.13     ~ 932 0
3 [CZM2007] 7 * 02 02 52.70 -03 15 56.2   19.07 18.15   17.16 ~ 1 0
4 [CZM2007] 8 * 02 02 55.20 -03 14 48.7   19.06     17.15 ~ 1 0
5 NAME Whiting 1 GlC 02 02 56.8 -03 15 10           ~ 106 0
6 [CZM2007] 6 * 02 02 57.10 -03 15 07.7   19.28 18.00   16.51 ~ 1 0
7 NAME Sgr Stream St* 02 22 +00.0           ~ 671 0
8 Cl Pal 1 GlC 03 33 20.04 +79 34 51.8   17.2       ~ 203 1
9 NGC 2141 OpC 06 02 55 +10 26.8   10.43 9.4     ~ 115 0
10 NGC 2682 OpC 08 51 18 +11 48.0           ~ 2061 0
11 NAME E 3 GlC 09 20 57.07 -77 16 54.8           ~ 130 0
12 NAME Segue 1 G 10 07 03.2 +16 04 25     15.3     ~ 367 1
13 C 1235-509 GlC 12 38 40.20 -51 09 01.0           ~ 324 0
14 C 1353-269 GlC 13 56 21.702 -27 10 03.00           ~ 104 0
15 NAME Serpens Dwarf GlC 15 16 05.30 -00 06 41.0   15.1       ~ 632 1
16 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11831 0
17 NAME SDG G 18 55 03.1 -30 28 42   4.5 3.6     ~ 1787 2
18 M 54 GlC 18 55 03.33 -30 28 47.5           ~ 918 0
19 Cl Terzan 7 GlC 19 17 43.92 -34 39 27.8           ~ 367 0
20 NGC 6791 OpC 19 20 53 +37 46.3   10.52 9.5     ~ 887 0
21 Cl Arp 2 GlC 19 28 44.11 -30 21 20.3     12.41     ~ 304 0
22 Cl Terzan 8 GlC 19 41 44.41 -33 59 58.1     11.54     ~ 262 0
23 M 71 GlC 19 53 46.49 +18 46 45.1   7.91 6.1     ~ 1028 0
24 M 15 GlC 21 29 58.33 +12 10 01.2   3       ~ 2925 0
25 Cl Pal 12 GlC 21 46 38.84 -21 15 09.4     11.89     ~ 455 0
26 GCl 124 GlC 23 06 44.48 +12 46 19.2   15.6       ~ 234 1

    Equat.    Gal    SGal    Ecl

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2020.11.28-21:58:35

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