On the mass-radius relation of hot stellar systems

Gieles, M., Baumgardt, H., Heggie, D. C. and Lamers, H. J. G. L. M. (2010) On the mass-radius relation of hot stellar systems. Monthly Notices of the Royal Astronomical Society: Letters, 408 1: L16-L20. doi:10.1111/j.1745-3933.2010.00919.x

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Author Gieles, M.
Baumgardt, H.
Heggie, D. C.
Lamers, H. J. G. L. M.
Title On the mass-radius relation of hot stellar systems
Journal name Monthly Notices of the Royal Astronomical Society: Letters   Check publisher's open access policy
ISSN 1745-3933
1745-3925
Publication date 2010-10
Sub-type Article (original research)
DOI 10.1111/j.1745-3933.2010.00919.x
Open Access Status File (Publisher version)
Volume 408
Issue 1
Start page L16
End page L20
Total pages 5
Place of publication Oxford, United Kingdom
Publisher Oxford University Press
Collection year 2011
Language eng
Formatted abstract
Most globular clusters have half-mass radii of a few pc with no apparent correlation with their masses. This is different from elliptical galaxies, for which the Faber-Jackson relation suggests a strong positive correlation between mass and radius. Objects that are somewhat in between globular clusters and low-mass galaxies, such as ultracompact dwarf galaxies, have a mass-radius relation consistent with the extension of the relation for bright ellipticals. Here we show that at an age of 10 Gyr a break in the mass-radius relation at ~ 106 M⊙ is established because objects below this mass, i.e. globular clusters, have undergone expansion driven by stellar evolution and hard binaries. From numerical simulations we find that the combined energy production of these two effects in the core comes into balance with the flux of energy that is conducted across the half-mass radius by relaxation. An important property of this 'balanced' evolution is that the cluster half-mass radius is independent of its initial value and is a function of the number of bound stars and the age only. It is therefore not possible to infer the initial mass-radius relation of globular clusters, and we can only conclude that the present day properties are consistent with the hypothesis that all hot stellar systems formed with the same mass-radius relation and that globular clusters have moved away from this relation because of a Hubble time of stellar and dynamical evolution. © 2010 The Authors. Journal compilation © 2010 RAS.
Keyword Methods: numerical
Globular clusters: general
Galaxies: fundamental parameters
Galaxies: star clusters
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
Official 2011 Collection
 
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Created: Sun, 07 Nov 2010, 00:04:22 EST