SCYON Abstract

Received on January 22 2008

The Distribution of Stellar Mass in the Pleiades

AuthorsJoseph M. Converse and Steven W. Stahler
AffiliationBerkeley Astronomy Dept Berkeley, CA 94720
Accepted byAstrophysical Journal
Contactjconverse@astro.berkeley.edu
URL
Links Pleiades

Abstract

As part of an effort to understand the origin of open clusters, we present a statistical analysis of the currently observed Pleiades. Starting with a photometric catalog of the cluster, we employ a maximum likelihood technique to determine the mass distribution of its members, including single stars and both components of binary systems. We find that the overall binary fraction for unresolved pairs is 68 percent. Extrapolating to include resolved systems, this fraction climbs to about 76 percent, significantly higher than the accepted field-star result. Both figures are sensitive to the cluster age, for which we have used the currently favored value of 125 Myr. The primary and secondary masses within binaries are correlated, in the sense that their ratios are closer to unity than under the hypothesis of random pairing. We map out the spatial variation of the cluster's projected and three-dimensional mass and number densities. Finally, we revisit the issue of mass segregation in the Pleiades. We find unambiguous evidence of segregation, and introduce a new method for quantifying it.