AIP astronomy picture of the month

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A new neighbour of the Sun, LHS 2090, is discovered from the combination of old high proper motion catalogues with a new near-infrared sky survey (2MASS) and follow-up spectroscopy. The left picture shows the change in position of the newly discovered nearby star. (credit: Digitized Sky Surveys, Palomar Schmidt Telescope). The right figure shows the spectrum of LHS 2090 (obtained at Calar Alto observatory) in comparison with that of the well-known M6.5 dwarf GJ 1111.
( credit: Scholz, Meusinger Jahreiss}

Reason for selection:

A new neighbour of the Sun: LHS 2090 at 6 pc

We present the discovery of a previously unknown very nearby star - LHS 2090 at a distance of only 6 pc. In order to find nearby (i.e. < 25 pc) red dwarfs, we re-identified high proper motion stars ( > 0.18 arcsec/yr) from the NLTT catalogue (Luyten 1979) in optical Digitized Sky Survey data for two different epochs and in the 2MASS data base. Only proper motion stars with large R-Ks colour index and with relatively bright infrared magnitudes (Ks) 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 JHKs magnitudes of LHS2090 with absolute magnitudes of M6.5 dwarfs is 6.0 +- 1.1 pc assuming an uncertainty in absolute magnitude of +- 0.4 mag.

For more information we refer to our paper: Scholz, Meusinger, Jahreiss, A&A, 374 (2001), L12 ( credit: Scholz, Meusinger Jahreiss )