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arXiv · 1009.0710

Calibration of radii and masses of open clusters with a simulation

A. Ernst·A. Just·P. Berczik·M. I. Petrov
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Abstract

Context: A recent new approach to apply a simple dynamical mass estimate of tidally limited star clusters is based on the identification of the tidal radius in a King profile with the dynamical Jacobi radius. The application to an unbiased open cluster catalogue yields significantly higher cluster masses compared to the classical methods. Aims: We quantify the bias in the mass determination as function of projection direction and cluster age by analysing a simulated star cluster. Methods: We use direct $N$-body simulations of a star cluster including stellar evolution in an analytic Milky Way potential and apply a best fit to the projected number density of cluster stars. Results: We obtain significantly overestimated star cluster masses which depend strongly on the viewing direction. The overestimation is typically in the range of 10-50 percent and reaches a factor of 3.5 for young clusters. Mass segregation reduces the derived limiting radii systematically.

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A. Ernst, A. Just, P. Berczik, M. I. Petrov. 2010-09-03. Calibration of radii and masses of open clusters with a simulation. https://doi.org/10.1051/0004-6361/201014901

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