2025AJ....169...81C

Query : 2025AJ....169...81C

2025AJ....169...81C - Astron. J., 169, 81 (2025/February-0)

On the Age Calibration of Open Clusters Using Red Clump Stars.

CHRISS A.R. and WORTHEY G.

Abstract (from CDS):

In this study, we extend the dust-independent Hatzidimitriou relation between cluster age and dB–R color difference between the red giant branch (RGB) and red clump to younger cluster ages. We perform membership analysis on 14 galactic open clusters using Gaia DR3 astrometry, then compute the difference in color of the RGB and red clump dB–R using Gaia photometry. We also compute dB–R for five fields surrounding Small Magellanic Cloud clusters. We find that the trend derived from older clusters does not extrapolate to younger ages and becomes double valued. We confirm that dB–R is independent of metallicity. Current stellar evolutionary isochrones do not quantitatively reproduce the trend and furthermore predict an increased color gap with a decrease in metallicity that is not echoed in the data. Integrated light models based on current isochrones exaggerate the color change over the ​​​​​​-0.5 < [Fe/H] < 0 interval at the few-percent level.

Abstract Copyright: © 2025. The Author(s). Published by the American Astronomical Society.

Journal keyword(s): Open star clusters - Stellar ages - Red giant clump - Red giant branch - Hertzsprung Russell diagram

Simbad objects: 32

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Number of rows : 32
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NGC 104 GlC 00 24 05.359 -72 04 53.20     4.09     ~ 4158 0
2 NGC 152 OpC 00 32 56.76 -73 06 56.4 13.37 13.05 12.26   11.13 ~ 96 0
3 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 12317 1
4 HW 30 Cl* 00 54 28 -73 37.1           ~ 8 0
5 HW 31 Cl* 00 55 33.74 -74 03 44.1 16.10 15.80 15.23   14.50 ~ 18 0
6 [BS95] 79 As* 00 56 04 -74 02.7           ~ 6 0
7 Bruck 136 Cl* 01 08 39.57 -71 45 35.1 15.44 14.98 14.27   13.09 ~ 9 0
8 NGC 752 OpC 01 56 53.7 +37 45 06           ~ 712 0
9 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 7988 0
10 Cl King 5 OpC 03 14 43.6 +52 41 52           ~ 84 0
11 NGC 1245 OpC 03 14 44.3 +47 14 06   9.16 8.4     ~ 171 0
12 NAME Eridanus Star Cluster GlC 04 24 44.5 -21 11 13           ~ 192 1
13 ESO 32-19 Cl* 04 44 40 -74 15.6   14.18 13.53     ~ 18 0
14 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 19090 0
15 NGC 1978 GlC 05 28 45.330 -66 14 12.04   10.7 10.70     ~ 317 0
16 NAME Hodge 4 GlC 05 32 25.64 -64 44 07.7     13.33     ~ 52 0
17 NGC 2173 GlC 05 57 58 -72 58.7   12.74 11.88     ~ 148 0
18 ESO 121-3 Cl* 06 02 03.32 -60 31 25.6   14.91 14.04     ~ 118 0
19 Cl Melotte 66 OpC 07 26 19.2 -47 41 14   8.73       ~ 213 0
20 Cl Melotte 71 OpC 07 37 31.3 -12 03 42   7.44 7.1     ~ 149 0
21 NGC 2420 OpC 07 38 24.6 +21 34 26   9.0 8.3     ~ 523 0
22 NGC 2477 OpC 07 52 11.4 -38 32 47   6.64 5.8     ~ 314 0
23 NGC 2506 OpC 08 00 02.3 -10 46 22   8.28 7.6     ~ 313 0
24 NGC 2509 OpC 08 00 48.4 -19 03 28     9.3     ~ 39 0
25 NGC 2627 OpC 08 37 13.9 -29 57 04     8.4     ~ 74 0
26 Cl VDBH 49 OpC 08 44 35.7 -35 54 02           ~ 26 0
27 NGC 2682 OpC 08 51 23.5 +11 48 54           ~ 2528 0
28 GCl 17 GlC 11 29 16.80 +28 58 25.0   14.4       ~ 379 1
29 NGC 6208 OpC 16 49 20.5 -53 43 27   8.06 7.2     ~ 94 0
30 NGC 6791 OpC 19 20 52.8 +37 46 40   10.52 9.5     ~ 1120 0
31 Cl Pal 12 GlC 21 46 38.84 -21 15 09.4     11.89     ~ 548 0
32 NGC 7789 OpC 23 57 19.4 +56 43 28   7.68 6.7     ~ 575 0

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