2009A&A...502..817A


Query : 2009A&A...502..817A

2009A&A...502..817A - Astronomy and Astrophysics, volume 502, 817-832 (2009/8-2)

The photometric evolution of dissolving star clusters. II. Realistic models. Colours and M/L ratios.

ANDERS P., LAMERS H.J.G.L.M. and BAUMGARDT H.

Abstract (from CDS):

Evolutionary synthesis models are the primary means of constructing spectrophotometric models of stellar populations, and deriving physical parameters from observations compared with these models. One of the basic assumptions of evolutionary synthesis models has been the time-independence of the stellar mass function, apart from the successive removal of high-mass stars by stellar evolution. However, dynamical simulations of star clusters in tidal fields have demonstrated that the mass function can be changed by the preferential removal of low-mass stars from clusters. We combine the results of dynamical simulations of star clusters in tidal fields with our evolutionary synthesis code GALEV. We extend the models to consider the total cluster disruption time as additional parameter. Following up on our earlier work, which was based on simplifying assumptions, we reanalyse the mass-function evolution found in N-body simulations of star clusters in tidal fields, parametrise it as a function of age and total disruption time of the cluster, and use this parametrisation to compute GALEV models as a function of age, metallicity, and total cluster disruption time. We study the impact of cluster dissolution on colours (which generally become redder) and magnitudes (which become fainter) of star clusters, their mass-to-light ratios (which can deviate by a factor of ∼2-4 from predictions of standard models without cluster dissolution), and quantify the effect of the altered integrated photometry on cluster age determination. In most cases, clusters appear to be older than they are, where the age difference can range from 20% to 200%. By comparing our model results with observed M/L ratios for old compact objects in the mass range 104.5-108M, we find a strong discrepancy for objects more massive than 107M, such that observed M/L ratios are higher than predicted by our models. This could be caused either by differences in the underlying stellar mass function or be an indication of the presence of dark matter in these objects. Less massive objects are well described by the models.

Abstract Copyright:

Journal keyword(s): Galaxy: globular clusters: general - Galaxy: open clusters and associations: general - galaxies: star clusters - methods: data analysis

VizieR on-line data: <Available at CDS (J/A+A/502/817): filelist.dat mag/* mass/* ori/*>

Simbad objects: 19

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Number of rows : 19
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 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 11546 1
2 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9993 1
3 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 15675 1
4 NGC 2257 Cl* 06 30 12 -64 19.6   13.24 12.62     ~ 208 0
5 NGC 2419 GlC 07 38 08.51 +38 52 54.9     10.05     ~ 863 0
6 NAME Vir I ClG 12 26 32.1 +12 43 24   10.00 8.49     ~ 6133 0
7 [CHA90] 114 G 12 30 45.91 +12 25 01.5   20.77 20.11     ~ 26 0
8 [PLP2016] 187.747336+12.356404 GlC 12 30 59.3678219155 +12 21 23.049345963   21.20 20.11     ~ 21 0
9 M 68 GlC 12 39 27.98 -26 44 38.6   10.26 7.96     ~ 922 0
10 NAME Centaurus A Sy2 13 25 27.61509104 -43 01 08.8056025   8.18 6.84 6.66   ~ 4153 3
11 M 3 GlC 13 42 11.62 +28 22 38.2     6.39     ~ 2343 0
12 NGC 5286 GlC 13 46 26.81 -51 22 27.3   9.18 8.31     ~ 393 0
13 NAME Serpens Dwarf GlC 15 16 05.30 -00 06 41.0   15.1       ~ 664 1
14 M 5 GlC 15 18 33.22 +02 04 51.7   7.34 5.95     ~ 1845 0
15 NGC 6366 GlC 17 27 44.24 -05 04 47.5           ~ 277 0
16 NAME Galactic Center gam 17 45 39.60213 -29 00 22.0000           ~ 12560 0
17 NGC 6535 GlC 18 03 50.51 -00 17 51.5   11.35 9.85     ~ 262 0
18 M 54 GlC 18 55 03.33 -30 28 47.5           ~ 973 0
19 M 2 GlC 21 33 27.02 -00 49 23.7     6.25     ~ 945 1

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2021.12.07-06:53:01

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