David Merritt


Also archived in: arXiv:astro-ph/0403331 v2 17 Mar 2004 Core radii of globular clusters in the Large and Small Magellanic Clouds show an increasing trend with age. We propose that this trend is a dynamical effect resulting from the accumulation of massive stars and stellarmass black holes at the cluster centers. The black holes are remnants of stars with initial masses exceeding ∼ 20 - 25M⊙; as their orbits decay by dynamical friction, they heat the stellar background and create a core. Using analytical estimates and N-body experiments, we show that the sizes of the cores so produced and their growth rates are consistent with what is observed. We propose that this mechanism is responsible for the formation of cores in all globular clusters and possibly in other systems as well (Refer to PDF file for exact formulas).

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Supported by NSF grant AST02-0631, NASA grant NAG5-9046, and grant HST-AR-09519.01-A from STScI. SPZ was supported by the Royal Netherlands Academy of Sciences (KNAW), the Dutch Organization of Science (NWO), and by the Netherlands Research School for Astronomy (NOVA).

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Department, Program, or Center

School of Physics and Astronomy (COS)


RIT – Main Campus