2004A&A...420..911S


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.03CET05:08:25

2004A&A...420..911S - Astronomy and Astrophysics, volume 420, 911-919 (2004/6-4)

The initial helium abundance of the Galactic globular cluster system.

SALARIS M., RIELLO M., CASSISI S. and PIOTTO G.

Abstract (from CDS):

In this paper we estimate the initial He content in about 30% of the Galactic globular clusters (GGCs) from new star counts we have performed on the recently published HST snapshot database of Colour Magnitude Diagrams (Piotto et al., 2002A&A...391..945P). More specifically, we use the so-called R-parameter and estimate the He content from a theoretical calibration based on a recently updated set of stellar evolution models. We performed an accurate statistical analysis in order to assess whether GGCs show a statistically significant spread in their initial He abundances, and whether there is a correlation with the cluster metallicity. As in previous works on the subject, we do not find any significant dependence of the He abundance on the cluster metallicity; this provides an important constraint for models of Galaxy formation and evolution. Apart from GGCs with the bluest Horizontal Branch morphology, the observed spread in the individual helium abundances is statistically compatible with the individual errors. This means that either there is no intrinsic abundance spread among the GGCs, or that this is masked by the errors. In the latter case we have estimated a firm 1σ upper limit of 0.019 to the possible intrinsic spread. In case of the GGCs with the bluest Horizontal Branch morphology we detect a significant spread towards higher abundances inconsistent with the individual errors; this can be fully explained by additional effects not accounted for in our theoretical calibrations, which do not affect the abundances estimated for the clusters with redder Horizontal Branch morphology. In the hypothesis that the intrinsic dispersion on the individual He abundances is zero, taking into account the errors on the individual R-parameter estimates, as well as the uncertainties on the cluster metallicity scale and theoretical calibration, we have determined an initial He abundance mass fraction YGGC=0.250±0.006. This value is in perfect agreement with current estimates based on Cosmic Microwave Background radiation analyses and cosmological nucleosynthesis computations.

Abstract Copyright:

Journal keyword(s): Galaxy: globular clusters: general - Galaxy: evolution - stars: evolution - stars: Population II

Simbad objects: 54

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Number of rows : 54

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     ~ 3618 0
2 NGC 362 GlC 01 03 14.26 -70 50 55.6     6.58     ~ 965 0
3 NGC 1261 GlC 03 12 16.21 -55 12 58.4     8.63     ~ 439 0
4 NGC 1851 GlC 05 14 06.76 -40 02 47.6   8.80 7.23     ~ 1268 0
5 M 79 GlC 05 24 10.59 -24 31 27.3   9.21 8.16     ~ 730 0
6 NGC 2808 GlC 09 12 03.10 -64 51 48.6   7.77 5.69     ~ 1277 0
7 NGC 3201 GlC 10 17 36.82 -46 24 44.9   9.18 8.24     ~ 747 0
8 NGC 4147 GlC 12 10 06.149 +18 32 31.78   11.45 10.74     ~ 504 0
9 NGC 4372 GlC 12 25 45.43 -72 39 32.7   10.86 9.85     ~ 269 0
10 M 68 GlC 12 39 27.98 -26 44 38.6   10.26 7.96     ~ 897 0
11 NGC 4833 GlC 12 59 33.92 -70 52 35.4   8.72 7.79     ~ 363 0
12 M 53 GlC 13 12 55.25 +18 10 05.4   8.95 7.79     ~ 732 0
13 M 3 GlC 13 42 11.62 +28 22 38.2     6.39     ~ 2298 0
14 NGC 5634 GlC 14 29 37.28 -05 58 35.1   10.69 10.05     ~ 255 0
15 NGC 5694 GlC 14 39 36.52 -26 32 18.0   11.58 10.89     ~ 272 0
16 IC 4499 GlC 15 00 18.57 -82 12 49.6     8.56     ~ 317 0
17 NGC 5824 GlC 15 03 58.612 -33 04 06.70   10.28 9.56     ~ 351 0
18 M 5 GlC 15 18 33.22 +02 04 51.7   7.34 5.95     ~ 1805 0
19 NGC 5927 GlC 15 28 00.69 -50 40 22.9   10.13 8.86     ~ 413 0
20 NGC 5946 GlC 15 35 28.58 -50 39 35.0   11.98 10.72     ~ 170 0
21 NGC 5986 GlC 15 46 03.00 -37 47 11.1     6.92     ~ 317 0
22 M 80 GlC 16 17 02.41 -22 58 33.9           ~ 637 0
23 NGC 6139 GlC 16 27 39.987 -38 50 57.03   11.03 9.68     ~ 184 0
24 M 107 GlC 16 32 31.86 -13 03 13.6   9.96 8.85     ~ 721 0
25 M 13 GlC 16 41 41.634 +36 27 40.75     5.8     ~ 2036 0
26 NGC 6229 GlC 16 46 58.641 +47 31 36.38   9.38 9.86     ~ 323 0
27 M 12 GlC 16 47 14.18 -01 56 54.7   8.52 6.07     ~ 593 0
28 NGC 6235 GlC 16 53 25.36 -22 10 38.8   11.99 7.20     ~ 164 0
29 M 62 GlC 17 01 12.60 -30 06 44.5   8.55 7.39     ~ 528 0
30 M 19 GlC 17 02 37.69 -26 16 04.6   8.45 5.57     ~ 319 1
31 NGC 6284 GlC 17 04 28.747 -24 45 51.22   10.72 7.43     ~ 245 0
32 NGC 6287 GlC 17 05 09.4907827015 -22 42 28.100632364   11.49 10.30     ~ 201 0
33 NGC 6293 GlC 17 10 10.42 -26 34 54.2   9.96 9.02     ~ 248 0
34 NGC 6304 GlC 17 14 32.25 -29 27 43.3   10.33 9.03     ~ 307 0
35 NGC 6342 GlC 17 21 10.14 -19 35 14.7   11.25 10.01     ~ 252 0
36 NGC 6356 GlC 17 23 34.99 -17 48 46.9   10.01 7.42     ~ 324 1
37 NGC 6362 GlC 17 31 54.99 -67 02 54.0   9.72 8.86     ~ 501 0
38 NGC 6388 GlC 17 36 17.461 -44 44 08.34   7.40       ~ 828 1
39 NGC 6441 GlC 17 50 13.06 -37 03 05.2   9.26 8.00     ~ 788 0
40 NGC 6522 GlC 18 03 34.08 -30 02 02.3   10.68 9.48     ~ 469 1
41 NGC 6544 GlC 18 07 20.58 -24 59 50.4   11.36 9.90     ~ 245 0
42 NGC 6569 GlC 18 13 38.88 -31 49 35.2   10.78 9.47     ~ 195 0
43 NGC 6584 GlC 18 18 37.60 -52 12 56.8   10.32 8.17     ~ 253 0
44 NGC 6624 GlC 18 23 40.51 -30 21 39.7           ~ 792 1
45 NGC 6638 GlC 18 30 56.25 -25 29 47.1   10.81 9.68     ~ 199 0
46 M 69 GlC 18 31 23.10 -32 20 53.1   9.32 8.31     ~ 416 1
47 NGC 6642 GlC 18 31 54.23 -23 28 34.1   11.30 10.24     ~ 167 0
48 NGC 6652 GlC 18 35 45.63 -32 59 26.6   10.64 9.75     ~ 362 0
49 M 70 GlC 18 43 12.76 -32 17 31.6   9.76 9.06     ~ 340 0
50 NGC 6717 GlC 18 55 06.04 -22 42 05.3   11.29 10.35     ~ 202 0
51 NGC 6723 GlC 18 59 33.15 -36 37 56.1           ~ 440 0
52 NGC 6760 GlC 19 11 12.06 +01 01 49.7   11.37 9.78     ~ 211 0
53 M 75 GlC 20 06 04.841 -21 55 20.14     8.26     ~ 322 0
54 M 15 GlC 21 29 58.33 +12 10 01.2   3       ~ 2943 0

    Equat.    Gal    SGal    Ecl

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2021.03.03-05:08:25

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