Letter to the Editor

Discovery of a widely separated binary system of very low mass stars

¹ Institute of Astronomy and Astrophysics, Academia Sinica, PO Box 23-141, Taipei 106, ROC, Taiwan e-mail: pbngoc@asiaa.sinica.edu.tw
² Instituto de Astrofísica de Canarias, C/ vía Láctea s/n, 38200 La Laguna (Tenerife), Spain
³ University of Central Florida, Dept. of Physics, PO Box 162385, Orlando, FL 32816-2385, USA
⁴ CNRS UMR6091, Observatoire de Besançon, BP 1615, 25010 Besançon Cedex, France
⁵ Canada-France-Hawaii Telescope Corporation, 65-1238 Mamalahoa Highway, Kamuela, HI 96743, USA
⁶ Laboratoire d'Astrophysique de Grenoble, Université J. Fourier, BP 53, 38041 Grenoble, France

Received: 3 June 2005
Accepted: 3 July 2005

Abstract

We report our discovery of a nearby wide binary system, LP 714-37 AB. Phan-Bao et al. identified LP 714-37 as a mid-M dwarf during a cross-identification of the NLTT and DENIS catalogues. Our CCD images resolve the system into a binary with a projected angular separation of 1.8´´, or 33 AU, and low-resolution optical spectra give spectral types of M5.5 (LP 714-37A) and M7.5 (LP 714-37B). This makes LP 714-37 AB one of very few widely separated (separation >30 AU) very low-mass binary systems known in the field, and we discuss it in the context of the multiplicity properties of very low-mass stars and brown dwarfs.