The mass of the Pleiades |
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| Authors: | Pinfield Jameson & Hodgkin |
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| Institution: | Department of Pure and Applied Physics, The Queen's University of Belfast, Belfast BT7 1NN,;Department of Physics and Astronomy, Leicester University, University Road, Leicester LE1 7RH |
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| Abstract: | A membership catalogue for the Pleiades is divided into four mass bins, and a tidally truncated King profile is fitted to each bin with good agreement with the data. The tidal radius of the cluster is found to be 13.1 pc, and the total mass of the cluster down to the stellar limit is calculated to be 735 M. The spread of stars in each bin, as well as the relaxation and crossing times, shows the Pleiades to be an approximately relaxed cluster with equilibrium between the density and velocity distributions. The cluster kinetic energy and binding energy are consistent with the virial theorem, indicating no large unseen population of brown dwarfs. However, the 1 σ errors in the cluster parameters provide an upper limit to the mass of any brown dwarf population of 131 M, which would show up in deep CCD surveys as ≤ 5.5 brown dwarfs per 10 × 10 arcminute field in the cluster centre. |
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| Keywords: | catalogues celestial mechanics stellar dynamics stars: low-mass brown dwarfs open clusters and associations: individual: Pleiades |
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