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The mass-to-light ratio of rich star clusters

Boily, Christian M. ; Fleck, Jean-Julien ; Lançon, Ariane and Renaud, Florent LU (2009) In Astrophysics and Space Science 324(2-4). p.265-269
Abstract
We point out a strong time evolution of the mass-to-light conversion factor, η, commonly used to estimate masses of unresolved star clusters from observed cluster spectrophotometric measures. We present a series of gas-dynamical models, coupled with the Cambridge stellar evolution tracks, to compute line-of-sight velocity dispersions and half-light radii weighted by the luminosity. We explore a range of initial conditions, varying in turn the cluster mass and/or density, and the stellar population’s initial mass function. We find that η, and hence the estimated cluster mass, may increase by as much as a factor of three over time-scales of 50 million yr. We apply these results to an hypothetic cluster mass distribution function (d.f.), and... (More)
We point out a strong time evolution of the mass-to-light conversion factor, η, commonly used to estimate masses of unresolved star clusters from observed cluster spectrophotometric measures. We present a series of gas-dynamical models, coupled with the Cambridge stellar evolution tracks, to compute line-of-sight velocity dispersions and half-light radii weighted by the luminosity. We explore a range of initial conditions, varying in turn the cluster mass and/or density, and the stellar population’s initial mass function. We find that η, and hence the estimated cluster mass, may increase by as much as a factor of three over time-scales of 50 million yr. We apply these results to an hypothetic cluster mass distribution function (d.f.), and show that the d.f. shape may be strongly affected at the low-mass end by this effect. Fitting truncated isothermal (Michie–King) models to the projected light profile leads to over-estimates of the concentration parameter, c, of δ c≈0.3 compared to the same functional fit applied to the projected mass density. (Less)
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author
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publishing date
type
Contribution to journal
publication status
published
subject
keywords
Stellar dynamics, Stars: evolution, Astrophysics - Cosmology and Nongalactic Astrophysics
in
Astrophysics and Space Science
volume
324
issue
2-4
pages
5 pages
publisher
Springer
external identifiers
  • scopus:84895911173
ISSN
0004-640X
DOI
10.1007/s10509-009-0118-3
language
English
LU publication?
no
id
157de64d-644e-458f-b617-5b7092636dfe
date added to LUP
2019-05-21 15:24:45
date last changed
2022-06-21 14:32:12
@article{157de64d-644e-458f-b617-5b7092636dfe,
  abstract     = {{We point out a strong time evolution of the mass-to-light conversion factor, η, commonly used to estimate masses of unresolved star clusters from observed cluster spectrophotometric measures. We present a series of gas-dynamical models, coupled with the Cambridge stellar evolution tracks, to compute line-of-sight velocity dispersions and half-light radii weighted by the luminosity. We explore a range of initial conditions, varying in turn the cluster mass and/or density, and the stellar population’s initial mass function. We find that η, and hence the estimated cluster mass, may increase by as much as a factor of three over time-scales of 50 million yr. We apply these results to an hypothetic cluster mass distribution function (d.f.), and show that the d.f. shape may be strongly affected at the low-mass end by this effect. Fitting truncated isothermal (Michie–King) models to the projected light profile leads to over-estimates of the concentration parameter, c, of δ c≈0.3 compared to the same functional fit applied to the projected mass density.}},
  author       = {{Boily, Christian M. and Fleck, Jean-Julien and Lançon, Ariane and Renaud, Florent}},
  issn         = {{0004-640X}},
  keywords     = {{Stellar dynamics, Stars: evolution, Astrophysics - Cosmology and Nongalactic Astrophysics}},
  language     = {{eng}},
  month        = {{12}},
  number       = {{2-4}},
  pages        = {{265--269}},
  publisher    = {{Springer}},
  series       = {{Astrophysics and Space Science}},
  title        = {{The mass-to-light ratio of rich star clusters}},
  url          = {{http://dx.doi.org/10.1007/s10509-009-0118-3}},
  doi          = {{10.1007/s10509-009-0118-3}},
  volume       = {{324}},
  year         = {{2009}},
}