A substellar mass function for Alpha Persei^*

¹ Laboratorio de Astrofísica Espacial y Física Fundamental, INTA, PO Box 50727, 28080 Madrid, Spain
² Laboratoire d'Astrophysique, Observatoire de Grenoble, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France e-mail: jerome.bouvier@obs.ujf-grenoble.fr
³ IPAC, California Institute of Technology, Pasadena, CA 91125, USA e-mail: stauffer@ipac.caltech.edu
⁴ Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany e-mail: nlodieu@aip.de,mjm@aip.de

Corresponding author: D. Barrado y Navascués, barrado@laeff.esa.es

Received: 18 March 2002
Accepted: 28 August 2002

Abstract

We present a deep, wide-field optical survey of the young stellar cluster Alpha Per, in which we have discovered a large population of candidate brown dwarfs. Subsequent infrared photometric follow-up shows that the majority of them are probable or possible members of the cluster, reaching to a minimum mass of 0.035 . We have used this list of members to derive the luminosity and mass functions of the substellar population of the cluster (, when expressed in the mass spectrum form ) and compared its slope to the value measure for the Pleiades. This comparison indicates that the two cluster mass functions are, indeed, very similar.