1998A&A...333..479S


Query : 1998A&A...333..479S

1998A&A...333..479S - Astronomy and Astrophysics, volume 333, 479-496 (1998/5-2)

The galactic globular cluster NGC 1851: its dynamical and evolutionary properties.

SAVIANE I., PIOTTO G., FAGOTTO F., ZAGGIA S., CAPACCIOLI M. and APARICIO A.

Abstract (from CDS):

We have completely mapped the Galactic globular cluster NGC 1851 with large-field, ground-based VI CCD photometry and pre-repair HST/WFPC1 data for the central region. The photometric data set has allowed a V vs. (V-I) colour-magnitude diagram for ∼20500 stars to be constructed. From the apparent luminosity of the horizontal branch (HB) we derive a true distance modulus (m-M)0=15.44±0.20. An accurate inspection of the cluster's bright and blue objects confirms the presence of seven ``supra-HB'' stars, six of which are identified as evolved descendants from HB progenitors. The HB morphology is found to be clearly bimodal, showing both a red clump and a blue tail, which are not compatible with standard evolutionary models. Synthetic Hertzsprung-Russell (HR) diagrams demonstrate that the problem could be solved by assuming a bimodal efficiency of the mass loss along the red giant branch (RGB). With the aid of Kolmogorov-Smirnov statistics we find evidence that the radial distribution of the blue HB stars is different from that of the red HB and supgiant branch (SGB) stars. We give the first measurement of the mean absolute I magnitude for 22 known RR Lyr variables (<MI(RR)≥0.12±0.20mag at a metallicity [Fe/H]=-1.28). The mean absolute V magnitude is <MV(RR)≥0.58±0.20mag, and we confirm that these stars are brighter than those of the zero-age HB (ZAHB). Moreover, we found seven new RR Lyr candidates (six ab type and one c type). With these additional variables the ratio of the two types is now Nc/Nab=0.38. From a sample of 25 globular clusters a new calibration for {DELTA} VbumpHB as a function of cluster metallicity is derived. NGC 1851 follows this general trend fairly well. From a comparison with the theoretical models, we also find some evidence for an age-metallicity relation among globular clusters. We identify 13 blue straggler stars, which do not show any sign of variability. The blue stragglers are less concentrated than the subgiant branch stars with similar magnitudes for r>80arcsec. Finally, a radial dependence of the luminosity function, a sign of mass segregation, is found. Transforming the luminosity function into a mass function (MF) and correcting for mass segregation by means of multi-mass King-Michie models, we find a global MF exponent x0=0.2±0.3.

Abstract Copyright:

Journal keyword(s): stars: evolution - Hertzsprung-Russell (HR) diagram - stars: luminosity function, mass function - stars: Population II - globular clusters: individual: NGC 1851

VizieR on-line data: <Available at CDS (J/A+A/333/479): appen.ps appen.tex cback.ps field1ms.ps xfig.ps>

Nomenclature: Table 7: Cl* NGC 1851 SPF 7-N (Nos 7-1 to 7-7). Table 8: Cl* NGC 1851 SPF 8-NN (Nos 8-1 to 8-13).

CDS comments: T.6 : * 99 (which numbering?), identified as Cl* NGC 1851 STET 368

Simbad objects: 46

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Number of rows : 46
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     ~ 3653 0
2 NGC 362 GlC 01 03 14.26 -70 50 55.6     6.58     ~ 978 0
3 PG 0231+051 WD* 02 33 41.3573346299 +05 18 43.652047965 14.562 15.776 16.096 16.267 16.639 DAO.6 140 0
4 Cl* NGC 1851 SAW V9 LP* 05 14 01.330 -40 02 05.81     13.37     ~ 5 0
5 [LBP2010] 207 RR* 05 14 02.750 -40 02 24.41           ~ 4 0
6 NGC 1851 GlC 05 14 06.76 -40 02 47.6           ~ 1289 0
7 Cl* NGC 1851 W 702 RR* 05 14 09.9016285849 -40 02 12.054461386   16.404 16.039     ~ 8 0
8 Cl* NGC 1851 STET 190 RR? 05 14 10.9566294114 -40 06 09.074079636   16.454 16.119     ~ 7 0
9 [YGN2015] NGC1851 NR 1290 RG* 05 14 19.3511488524 -40 04 23.824040671   15.02 13.30     ~ 10 0
10 UCAC2 31519456 * 15 38 57.6543814623 -00 43 06.456645230 16.079 16.161 16.046 16.078 16.557 ~ 5 0
11 M 80 GlC 16 17 02.41 -22 58 33.9           ~ 648 0
12 M 4 GlC 16 23 35.22 -26 31 32.7           ~ 1724 0
13 NGC 6352 GlC 17 25 29.11 -48 25 19.8   9.95 8.87     ~ 358 0
14 M 75 GlC 20 06 04.841 -21 55 20.14     8.26     ~ 326 0
15 M 30 GlC 21 40 22.12 -23 10 47.5     7.10     ~ 952 0
16 Cl* NGC 1851 SPF 7-1 V*? ~ ~     15.39     ~ 1 0
17 Cl* NGC 1851 SPF 7-2 V*? ~ ~     16.22     ~ 1 0
18 Cl* NGC 1851 SPF 7-3 V*? ~ ~   16.37       ~ 1 0
19 Cl* NGC 1851 SPF 7-4 * ~ ~     16.21     ~ 1 0
20 Cl* NGC 1851 SPF 7-5 V*? ~ ~     15.91     ~ 1 0
21 Cl* NGC 1851 SPF 7-6 V*? ~ ~     15.97     ~ 1 0
22 Cl* NGC 1851 SPF 7-7 V*? ~ ~     16.19     ~ 1 0
23 Cl* NGC 1851 SPF 8-1 * ~ ~     17.60     ~ 1 0
24 Cl* NGC 1851 SPF 8-2 * ~ ~     18.31     ~ 1 0
25 Cl* NGC 1851 SPF 8-3 * ~ ~     18.95     ~ 1 0
26 Cl* NGC 1851 SPF 8-4 * ~ ~   18.40       ~ 1 0
27 Cl* NGC 1851 SPF 8-5 * ~ ~     18.59     ~ 1 0
28 Cl* NGC 1851 SPF 8-6 * ~ ~   18.63       ~ 1 0
29 Cl* NGC 1851 SPF 8-7 * ~ ~     18.11     ~ 1 0
30 Cl* NGC 1851 SPF 8-8 * ~ ~     18.70     ~ 1 0
31 Cl* NGC 1851 SPF 8-9 * ~ ~   18.72       ~ 1 0
32 Cl* NGC 1851 SPF 8-10 * ~ ~     19.13     ~ 1 0
33 Cl* NGC 1851 SPF 8-11 * ~ ~     18.54     ~ 1 0
34 Cl* NGC 1851 SPF 8-12 * ~ ~   17.87       ~ 1 0
35 Cl* NGC 1851 SPF 8-13 * ~ ~     19.12     ~ 1 0
36 Cl* NGC 1851 W 626 * ~ ~   16.343 16.118     ~ 5 0
37 Cl* NGC 1851 W 544 * ~ ~   16.295 16.067     ~ 6 0
38 Cl* NGC 1851 W 586 * ~ ~   16.307 16.054     ~ 5 0
39 Cl* NGC 1851 STET 244 * ~ ~   16.54       ~ 2 0
40 Cl* NGC 1851 STET 368 * ~ ~   16.27 15.90     ~ 3 0
41 Cl* NGC 1851 W 710 * ~ ~   16.18 15.91     ~ 5 0
42 Cl* NGC 1851 W 703 * ~ ~   16.489 16.127     ~ 5 0
43 Cl* NGC 1851 W 688 * ~ ~   16.28 16.03     ~ 6 0
44 Cl* NGC 1851 W 418 * ~ ~   15.919 15.449     ~ 4 0
45 Cl* NGC 1851 W 505 * ~ ~   16.148 15.851     ~ 4 0
46 Cl* NGC 1851 W 647 * ~ ~   16.328 16.111     ~ 5 0

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2021.08.04-00:08:49

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