New neighbours

VI. Spectroscopy of DENIS nearby stars candidates

¹ GEPI, Observatoire de Paris, 5 place J. Janssen, 92195 Meudon Cedex, France e-mail: francoise.crifo@obspm.fr
² Institute of Astronomy and Astrophysics, Academia Sinica. PO Box 23-141, Taipei 106, Taiwan, ROC
³ University of Hue, Dept. of Physics, 32 Le Loi, Hue, Vietnam
⁴ Laboratoire d'Astrophysique de Grenoble, Université J. Fourier, BP 53, 38041 Grenoble, France
⁵ Canada-France-Hawaii Telescope Corporation, 65-1238 Mamalahoa Highway, Kamuela, HI 96743 USA
⁶ Centre d'Analyse des Images, GEPI, Observatoire de Paris, 61 avenue de l'Observatoire, 75014 Paris, France
⁷ Instituto de Astrofísica de Canarias, C/ Vía Láctea s/n, 38200 La Laguna (Tenerife), Spain
⁸ University of Central Florida, Dept. of Physics, PO Box 162385, Orlando, FL 32816-2385, USA
⁹ CNRS UMR 6091, Observatoire de Besançon, BP 15, 25010 Besançon Cedex, France

Received: 5 March 2005
Accepted: 7 June 2005

Abstract

We present spectra of 36 nearby star candidates and 3 red giant candidates, identified in the DENIS database. 32 of the dwarf candidates are nearby red dwarfs, with spectral types from M 5.5 to M 8.5. Out of 11 targets with low proper motion ( arcsec yr) but a Reduced Proper Motion above an inclusive threshold, 9 are red dwarfs. The 4 contaminants are all reddened F–K main sequence stars, and could have been eliminated by checking for small well-known high latitude molecular clouds. These stars might be of interest as probes of interstellar absorption. For the red dwarfs we derive spectral types and spectroscopic distances, using a new calibration of the PC3 spectral index to absolute magnitudes in the and K photometric bands.
We confirm 2 new members of the 12 pc volume (2 new M 8.5), and one M 7.5 NLTT object closer than 10 pc; and show that one quarter of the stars with photometric distances under 30 pc have too small a proper motion for inclusion in the NLTT catalog.