Volume 416, Number 3, March IV 2004
|Page(s)||L17 - L20|
|Published online||09 March 2004|
Letter to the Editor
Discovery of very nearby ultracool dwarfs from DENIS*
Laboratoire d'Astrophysique de Grenoble, Université Joseph Fourier, 38041 Grenoble Cedex 9, France e-mail: firstname.lastname@example.org
2 Instituto de Astrofísica de Canarias, via Láctea, 38200 La Laguna, Tenerife, Spain e-mail: email@example.com
3 CFHT Corporation, 68–1238 Mamalahoa Highway, Kamuela, HI 96743, USA
Corresponding author: T. R. Kendall, firstname.lastname@example.org
Accepted: 7 February 2004
We report new spectroscopic results, obtained with UKIRT/CGS4, of a sample of 14 candidate ultracool dwarfs selected from the DENIS (Deep Near-Infrared Survey of the Southern Sky) database. A further object, selected from the 2MASS Second Incremental Release, was observed at a later epoch with the same instrument. Six objects are already known in the literature; we re-derive their properties. A further four prove to be very nearby (10 pc) mid-to-late L-dwarfs, three unknown hitherto, two of which are almost certainly substellar. These findings increase the number of L-dwarfs known within ~10 pc by ~25%. The remainder of the objects discussed here are early L or very late M-type dwarfs lying between ~45 and 15 pc and are also new to the literature. Spectral types have been derived by direct comparison with J-, H- and K- band spectra of known template ultracool dwarfs given by Leggett et al. For the known objects, we generally find agreement to within ~1 subclass with previously derived spectral types. Distances are determined from the most recent MJ vs. spectral type calibrations, and together with our derived proper motions yield kinematics for most targets consistent with that expected for the disk population; for three probable late M-dwarfs, membership of a dynamically older population is postulated. The very nearby L-type objects discussed here are of great interest for future studies of binarity and parallaxes.
Key words: stars: low mass, brown dwarfs / stars: late-type / stars: kinematics / stars: distances / infrared: stars / surveys
© ESO, 2004
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