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Issue A&A
Volume 374, Number 2, August I 2001
Page(s) L12 - L15
Section Letters
DOI 10.1051/0004-6361:20010811



A&A 374, L12-L15 (2001)
DOI: 10.1051/0004-6361:20010811

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

I. Discovery of LHS 2090 at spectroscopic distance of $\mathsf{{\vec d} \sim 6}$ pc
R.-D. Scholz1, H. Meusinger2 and H. Jahreiß3

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

(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 d=6 pc. In order to find nearby (i.e. d < 25 pc) red dwarfs, we re-identified high proper motion stars ( $\mu > 0.18$ arcsec/yr) from the NLTT catalogue (Luyten 1979-1980) in optical Digitized Sky Survey data for two different epochs and in the 2MASS data base. Only proper motion stars with large $R-K_{\rm s}$ colour index and with relatively bright infrared magnitudes ( $K_{\rm s}< 10$) 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 $JHK_{\rm s}$ magnitudes of LHS 2090 with absolute magnitudes of M6.5 dwarfs is $6.0\pm1.1$ pc assuming an uncertainty in absolute magnitude of $\pm$0.4 mag.


Key words: astrometry and celestial mechanics: astrometry -- astronomical data base: surveys -- stars: late-type -- stars: low mass, brown dwarfs

Offprint request: R.-D. Scholz, rdscholz@aip.de

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© ESO 2001


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