Search for nearby stars among proper motion stars selected by optical-to-infrared photometry

I. Discovery of LHS 2090 at spectroscopic distance of pc

¹ Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany e-mail: rdscholz@aip.de
² Thüringer Landessternwarte Tautenburg, 07778 Tautenburg, Germany e-mail: meus@obelix.tls-tautenburg.de
³ Astronomisches Rechen-Institut, Mönchhofstraße 12-14, 69120 Heidelberg, Germany e-mail: hartmut@ari.uni-heidelberg.de

Corresponding author: R.-D. Scholz, rdscholz@aip.de

Received: 1 June 2001
Accepted: 11 June 2001

Abstract

We present the discovery of a previously unknown very nearby star -LHS 2090 at a distance of only pc. In order to find nearby (i.e. pc) red dwarfs, we re-identified high proper motion stars ( arcsec/yr) from the NLTT catalogue (Luyten [CITE]) in optical Digitized Sky Survey data for two different epochs and in the 2MASS data base. Only proper motion stars with large colour index and with relatively bright infrared magnitudes () were selected for follow-up spectroscopy. The low-resolution spectrum of LHS 2090 and its large proper motion (0.79 arcsec/yr) classify this star as an M6.5 dwarf. The resulting spectroscopic distance estimate from comparing the infrared JHK_s magnitudes of LHS 2090 with absolute magnitudes of M6.5 dwarfs is pc assuming an uncertainty in absolute magnitude of ±0.4 mag.