2009ApJ...694.1498M


Query : 2009ApJ...694.1498M

2009ApJ...694.1498M - Astrophys. J., 694, 1498-1516 (2009/April-1)

The ACS survey of galactic globular clusters. VII. Relative ages.

MARIN-FRANCH A., APARICIO A., PIOTTO G., ROSENBERG A., CHABOYER B., SARAJEDINI A., SIEGEL M., ANDERSON J., BEDIN L.R., DOTTER A., HEMPEL M., KING I., MAJEWSKI S., MILONE A.P., PAUST N. and REID I.N.

Abstract (from CDS):

The ACS Survey of Galactic globular clusters is a Hubble Space Telescope Treasury program designed to provide a new large, deep, and homogeneous photometric database. Based on observations from this program, we have measured precise relative ages for a sample of 64 Galactic globular clusters by comparing the relative position of the clusters' main-sequence (MS) turnoffs, using MS fitting to cross-compare clusters within the sample. This method provides relative ages to a formal precision of 2%-7%. We demonstrate that the calculated relative ages are independent of the choice of theoretical model. We find that the Galactic globular cluster sample can be divided into two groups–a population of old clusters with an age dispersion of ∼5% and no age-metallicity relation, and a group of younger clusters with an age-metallicity relation similar to that of the globular clusters associated with the Sagittarius dwarf galaxy. These results are consistent with the Milky Way halo having formed in two phases or processes. The first one would be compatible with a rapid (<0.8 Gyr) assembling process of the halo, in which the clusters in the old group were formed. Also these clusters could have been formed before re-ionization in dwarf galaxies that would later merge to build the Milky Way halo as predicted by ΛCDM cosmology. However, the galactocentric metallicity gradient shown by these clusters seems difficult to reconcile with the latter. As for the younger clusters, it is very tempting to argue that their origin is related to their formation within Milky Way satellite galaxies that were later accreted, but the origin of the age-metallicity relation remains unclear.

Abstract Copyright:

Journal keyword(s): Galaxy: evolution - Galaxy: formation - globular clusters: general

Simbad objects: 77

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Number of rows : 77
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     ~ 3748 0
2 NGC 288 GlC 00 52 45.24 -26 34 57.4   10 8.13     ~ 991 0
3 NGC 362 GlC 01 03 14.26 -70 50 55.6     6.58     ~ 1019 0
4 NGC 1261 GlC 03 12 16.21 -55 12 58.4     8.63     ~ 476 0
5 Cl Pal 1 GlC 03 33 20.04 +79 34 51.8   17.2       ~ 225 1
6 NAME E 1 GlC 03 55 02.5 -49 36 52           ~ 192 0
7 NAME CL ERID 1 GlC 04 24 44.5 -21 11 13           ~ 169 1
8 Cl Pal 2 GlC 04 46 05.91 +31 22 53.4   15       ~ 163 0
9 NGC 1851 GlC 05 14 06.76 -40 02 47.6           ~ 1341 0
10 M 79 GlC 05 24 10.59 -24 31 27.3   9.21 8.16     ~ 769 0
11 NAME Mon R2 HII 06 07 47.58 -06 22 42.6           ~ 702 2
12 NGC 2298 GlC 06 48 59.41 -36 00 19.1   10.77 8.89     ~ 465 0
13 NAME CMa Dwarf Galaxy G 07 12.6 -27 40     -0.1     ~ 198 1
14 NGC 2808 GlC 09 12 03.10 -64 51 48.6           ~ 1345 0
15 NAME E 3 GlC 09 20 57.07 -77 16 54.8           ~ 151 0
16 NAME Sextans C GlC 10 05 30.96 +00 04 15.4   15.5 13.9     ~ 310 1
17 NGC 3201 GlC 10 17 36.82 -46 24 44.9           ~ 804 0
18 GCl 17 GlC 11 29 16.80 +28 58 25.0   14.4       ~ 335 1
19 NGC 4147 GlC 12 10 06.149 +18 32 31.78   11.45 10.74     ~ 542 0
20 M 68 GlC 12 39 27.98 -26 44 38.6   10.26 7.96     ~ 942 0
21 NGC 4833 GlC 12 59 33.92 -70 52 35.4   8.72 7.79     ~ 389 0
22 M 53 GlC 13 12 55.25 +18 10 05.4   8.95 7.79     ~ 780 0
23 NGC 5053 GlC 13 16 27.09 +17 42 00.9     9.96     ~ 584 0
24 NGC 5139 GlC 13 26 47.28 -47 28 46.1   6.12 5.33     ~ 3264 0
25 M 3 GlC 13 42 11.62 +28 22 38.2     6.39     ~ 2384 0
26 NGC 5286 GlC 13 46 26.81 -51 22 27.3   9.18 8.31     ~ 408 0
27 NGC 5466 GlC 14 05 27.29 +28 32 04.0   10.5 9.70     ~ 785 0
28 M 5 GlC 15 18 33.22 +02 04 51.7   7.34 5.95     ~ 1887 0
29 NGC 5927 GlC 15 28 00.69 -50 40 22.9   10.13 8.86     ~ 434 0
30 ESO 224-8 OpC 15 39 05.4 -50 03 02           ~ 61 0
31 NGC 5986 GlC 15 46 03.00 -37 47 11.1     6.92     ~ 341 0
32 GCl 38 GlC 16 10 59.00 +14 57 42.0           ~ 347 0
33 Cl Lynga 7 GlC 16 11 03.65 -55 19 04.0           ~ 103 0
34 UGC 10310 IG 16 16 17.9000468088 +47 02 43.128874644   14.9       ~ 133 0
35 M 80 GlC 16 17 02.41 -22 58 33.9           ~ 673 0
36 M 4 GlC 16 23 35.22 -26 31 32.7           ~ 1771 0
37 NGC 6101 GlC 16 25 48.12 -72 12 07.9   10.90 10.08     ~ 268 0
38 NGC 6144 GlC 16 27 13.86 -26 01 24.6   10.55 9.63     ~ 226 0
39 M 107 GlC 16 32 31.86 -13 03 13.6   9.96 8.85     ~ 753 0
40 M 13 GlC 16 41 41.634 +36 27 40.75     5.8     ~ 2115 0
41 M 12 GlC 16 47 14.18 -01 56 54.7   8.52 6.07     ~ 629 0
42 M 10 GlC 16 57 09.05 -04 06 01.1     4.98     ~ 749 0
43 ClG 1710-2507 ClG 17 13 39 -25 11.1           ~ 15 0
44 NGC 6304 GlC 17 14 32.25 -29 27 43.3   10.33 9.03     ~ 332 0
45 M 92 GlC 17 17 07.39 +43 08 09.4     6.52     ~ 2006 0
46 NGC 6352 GlC 17 25 29.11 -48 25 19.8   9.95 8.87     ~ 371 0
47 NGC 6366 GlC 17 27 44.24 -05 04 47.5           ~ 287 0
48 NGC 6362 GlC 17 31 54.99 -67 02 54.0   9.72 8.86     ~ 540 0
49 NGC 6388 GlC 17 36 17.461 -44 44 08.34   7.40       ~ 867 1
50 NGC 6397 GlC 17 40 42.09 -53 40 27.6     5.17     ~ 1892 1
51 NGC 6441 GlC 17 50 13.06 -37 03 05.2   9.26 8.00     ~ 835 0
52 NGC 6496 GlC 17 59 03.68 -44 15 57.4   9.96       ~ 208 0
53 NGC 6535 GlC 18 03 50.51 -00 17 51.5   11.35 9.85     ~ 271 0
54 NGC 6541 GlC 18 08 02.36 -43 42 53.6   8.06 7.32     ~ 350 1
55 NGC 6584 GlC 18 18 37.60 -52 12 56.8   10.32 8.17     ~ 268 0
56 NGC 6624 GlC 18 23 40.51 -30 21 39.7           ~ 833 1
57 M 69 GlC 18 31 23.10 -32 20 53.1   9.32 8.31     ~ 440 1
58 NGC 6652 GlC 18 35 45.63 -32 59 26.6   10.64 9.75     ~ 397 0
59 M 22 GlC 18 36 23.94 -23 54 17.1   7.16 6.17     ~ 1304 0
60 M 70 GlC 18 43 12.76 -32 17 31.6   9.76 9.06     ~ 357 0
61 NAME SDG G 18 55 03.1 -30 28 42   4.5 3.6     ~ 1988 2
62 M 54 GlC 18 55 03.33 -30 28 47.5           ~ 1007 0
63 NGC 6717 GlC 18 55 06.04 -22 42 05.3   11.29 10.35     ~ 224 0
64 NGC 6723 GlC 18 59 33.15 -36 37 56.1           ~ 473 0
65 NGC 6752 GlC 19 10 52.11 -59 59 04.4   6.96 6.28     ~ 1910 0
66 M 56 GlC 19 16 35.57 +30 11 00.5   8.90       ~ 397 0
67 Cl Terzan 7 GlC 19 17 43.92 -34 39 27.8           ~ 402 0
68 M 55 GlC 19 39 59.71 -30 57 53.1     6.49     ~ 813 0
69 Cl Terzan 8 GlC 19 41 44.41 -33 59 58.1     11.54     ~ 296 0
70 M 71 GlC 19 53 46.49 +18 46 45.1   7.91 6.1     ~ 1078 0
71 NGC 6934 GlC 20 34 11.37 +07 24 16.1   10.48 9.75     ~ 393 0
72 M 72 GlC 20 53 27.70 -12 32 14.3   9.95 8.96     ~ 397 0
73 M 15 GlC 21 29 58.33 +12 10 01.2   3       ~ 3037 0
74 M 2 GlC 21 33 27.02 -00 49 23.7     6.25     ~ 972 1
75 M 30 GlC 21 40 22.12 -23 10 47.5     7.10     ~ 987 0
76 Cl Pal 12 GlC 21 46 38.84 -21 15 09.4     11.89     ~ 492 0
77 NAME Monoceros Stream St* ~ ~           ~ 339 0

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2022.09.28-02:45:21

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