SCYON Abstract

Received on December 8 2000

Proper motion of very low mass stars and brown dwarfs in the Pleiades cluster

AuthorsE. Moraux1, J. Bouvier1, and J.R. Stauffer2
Affiliation1 Laboratoire d'Astrophysique, Observatoire de Grenoble,
Université Joseph Fourier, B.P. 53, 38041 Grenoble Cedex 9, France
2 SIRTF Science Center, Caltech, Pasadena, CA 91125
Accepted byA\&A


We report proper motion measurements for 25 very-low mass (VLM) star and brown dwarf (BD) candidates of the Pleiades cluster previouslyidentified by Bouvier et al. (1998). Proper motions are measured with an accuracy of 9 mas/yr, compared to an expected tangential motion ofabout 50 mas/yr for Pleiades members. Of the 25 candidates, 15 have a membership probability of 95% or more and 7 are rejected as being field dwarfs. The 3 remaining candidates exhibit independent evidence for membership (lithium absorption or long-term proper motion). From the firm identification of Pleiades VLM and BD members, the cluster's substellar mass function is revised to $dN/dM ~ M-0.5 in the mass range from 0.04 to 0.3MO.