SCYON Abstract

Received on December 8 2000

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

Authors	E. Moraux¹, J. Bouvier¹, and J.R. Stauffer²
Affiliation	¹ 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 by	A\&A
Contact	moraux@laog.obs.ujf-grenoble.fr
URL	http://www-laog.obs.ujf-grenoble.fr/activites/starform/formation.html
Links	Pleiades

Abstract

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 0.3M_O.