Very low-mass members of the Lupus 3 cloud

¹ Departament d'Astronomia i Meteorologia, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain e-mail: blopez@am.ub.es
² Thüringer Landessternwarte, Sternwarte 5, 07778 Tautenburg, Germany e-mail: jochen@tls-tautenburg.de
³ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany e-mail: mundt@mpia-hd.mpg.de

Received: 2 November 2004
Accepted: 4 May 2005

Abstract

We report on a multi-band survey for very low-mass stars and brown dwarfs in the Lupus 3 cloud with the Wide Field Imager (WFI) at the ESO/MPG 2.2 m telescope on La Silla Observatory (Chile). Our multiband optical photometry is combined with available 2MASS JHK photometry to identify 19 new young stars and 3 brown dwarf candidates as probable members of this star forming region. Our objects are mostly clustered around the cloud core. Stars and brown dwarfs have similar levels of Hα emission, probably a signature of accretion. One object, a brown dwarf candidate, exhibits a near-infrared excess, which may indicate the presence of a disk, but its Hα emission cannot be confirmed due to its faintness in the optical passbands. We also find two visual pairs of probable Lupus 3 members that may be wide binaries.