Astron. Astrophys. Suppl. Ser. 135, 41-56

Searching for very low-mass stars and brown dwarfs with DENIS

X. Delfosse^1,2 - C.G. Tinney³ - T. Forveille¹ - N. Epchtein^4,5 - J. Borsenberger⁶ - P. Fouqué^4,7 - S. Kimeswenger⁸ -
D. Tiphène⁴

Send offprint request: X. Delfosse,
e-mail: Xavier.Delfosse@obs.ujf-grenoble.fr

1 - Observatoire de Grenoble, 414 rue de la Piscine, Domaine Universitaire de S$^{\mathrm t}$ Martin d'Hères, F-38041 Grenoble, France
2 - Observatoire de Genève, CH-1290 Sauverny, Switzerland
3 - Anglo-Australian Observatory, PO Box 296, Epping. N.S.W. 2121, Australia
4 - DESPA, Observatoire de Paris, 5 place J. Janssen, F-92195 Meudon Cedex, France
5 - Observatoire de Nice, BP. 4229, 06304 Nice Cedex 4, France
6 - Institut d'Astrophysique de Paris, 98 bis, Bd. Arago, F-75014 Paris, France
7 - European Southern Observatory, Casilla 19001, Santiago 19, Chile
8 - Institut für Astronomie der Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria

Received June 2; accepted September 23, 1998

Abstract:

We present the results of infrared spectroscopic observations of a sample of very low-mass stars and brown dwarf candidates detected in a 230 square degree area by the DENIS (DEep Near Infrared Southern sky; Epchtein, 1997) survey. We find that objects as faint as the faintest known stars are easily detected by DENIS. This sample also includes three members of the new "L'' dwarf class, one of which was the first confirmed isolated field brown dwarf. As this data represents $\sim 1\%$ of the total DENIS survey area, the completed survey can be expected to have a dramatic impact on the study of the faintest stars and brown dwarfs. In particular, it should detect $\sim$300 of the new and poorly understood "L'' class of dwarfs.

Key words: stars: low-mass,brown dwarfs -- stars: luminosity function, mass function -- infrared: stars -- surveys