Publication Date:
2014-06-13
Description:
We present a new version of the fast star cluster evolution code Evolve Me A Cluster of StarS ( emacss ). While previous versions of emacss reproduced clusters of single-mass stars, this version models clusters with an evolving stellar content. Stellar evolution dominates early evolution, and leads to: (1) reduction of the mean mass of stars due to the mass loss of high-mass stars; (2) expansion of the half-mass radius; (3) for (nearly) Roche Volume filling clusters, the induced escape of stars. Once sufficient relaxation has occurred (~=10 relaxation times-scales), clusters reach a second, ‘balanced’ state whereby the core releases energy as required by the cluster as a whole. In this state: (1) stars escape due to tidal effects faster than before balanced evolution; (2) the half-mass radius expands or contracts depending on the Roche volume filling factor; and (3) the mean mass of stars increases due to the preferential ejection of low-mass stars. We compare the emacss results of several cluster properties against N -body simulations of clusters spanning a range of initial number of stars, mass, half-mass radius, and tidal environments, and show that our prescription accurately predicts cluster evolution for this data base. Finally, we consider applications for emacss , such as studies of galactic globular cluster populations in cosmological simulations.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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