Search for nearby stars among proper motion stars selected by optical-to-infrared photometry. I. Discovery of LHS 2090 at spectroscopic distance of d=6pc

TL;DR

This paper reports the discovery of a new nearby star, LHS 2090, at approximately 6 parsecs away, identified through proper motion and photometric analysis, expanding our knowledge of local stellar populations.

Contribution

The study introduces a method combining optical-to-infrared photometry and proper motion data to identify previously unknown nearby red dwarfs, exemplified by LHS 2090.

Findings

LHS 2090 is an M6.5 dwarf at about 6 parsecs.

Proper motion and photometry effectively identify nearby stars.

LHS 2090's spectroscopic distance confirms its proximity.

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 \cite{luyten7980}) in optical Digitized Sky Survey data for two different epochs and in the 2MASS data base. Only proper motion stars with large $R-K_s$ colour index and with relatively bright infrared magnitudes ($K_s<10$) 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 $JHK_s$ 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.