N-body models of globular clusters: metallicities, half-light radii and mass-to-light ratios

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N-body models of globular clusters: metallicities, half-light radii and mass-to-light ratios

Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/238555

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Title: N-body models of globular clusters: metallicities, half-light radii and mass-to-light ratios
Author(s): Sippel, Anna C.; Hurley, Jarrod R.; Madrid, Juan P.; Harris, William E.
Abstract: Size differences of ≈20 percent between red (metal-rich) and blue (metal-poor) subpopulations of globular clusters have been observed, generating an ongoing debate as to whether these originate from projection effects or the difference in metallicity. We present direct N-body simulations of metal-rich and metal-poor stellar populations evolved to study the effects of metallicity on cluster evolution. The models start with N = 100000 stars and include primordial binaries. We also take metallicity-dependent stellar evolution and an external tidal field into account. We find no significant difference for the half-mass radii of those models, indicating that the clusters are structurally similar. However, utilizing observational tools to fit half-light (or effective) radii confirms that metallicity effects related to stellar evolution combined with dynamical effects such as mass segregation produce an apparent size difference of 17 per cent on average. The metallicity effect on the overall cluster luminosity also leads to higher mass-to-light ratios for metal-rich clusters.
Publication type: Journal article
Research centre: Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing
Source: Monthly Notices of the Royal Astronomical Society, Vol. 427, no. 1 (Nov 2012), pp. 167-179
Publication year: 2012
FOR Code(s): 0201 Astronomical and Space Sciences
Keyword(s): Globular clusters; Luminosity function; Mass function; Mass-loss rate; Star clusters; Stars evolution
Publisher: Wiley-Blackwell Publishing
ISSN: 0035-8711
Publisher URL: http://dx.doi.org/10.1111/j.1365-2966.2012.21969.x
Peer reviewed