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Description
The Third Catalogue of Nearby Stars (Gliese & Jahreiss, "Preliminary Version of the third Catalogue of Nearby Stars" (CNS3), 1991, catalog <V/70>) includes over 1850 stars which lie north of Dec.= -30{deg} and are either identified as spectral type M, or are unclassified but with an absolute visual magnitude estimate M_V_ > +8.0. Although there is no uniformity in selection criteria, and many of the stars lack basic data (radial velocities, spectral types, accurate photometry), the observational properties of these stars underlie most estimates of the fundamental characteristics of the Galactic Disk. We have obtained optical spectroscopy of 1746 of the 1876 stars -- the remaining 130 are binary companions of brighter stars and inaccessible to our observations. These spectra allow us, first, to exclude 61 stars as either degenerates or as misclassified earlier-type (B-K) stars lying beyond the 25 pc limit; to establish radial velocities accurate to +/-10km/s for all stars confirmed as late-type dwarfs; to determine spectral types and absolute magnitudes from the TiO bandstrength, allowing more accurate distance estimates for stars with inaccurate (or no) trigonometric parallax measurements; and to identify stars with H{alpha} emission (chromospherically active stars) and with strong CaH absorption (perhaps including some metal-poor disk subdwarfs). We have determined the nearby-star luminosity function from complete samples derived by applying both the distance limits defined by Wielen (1974, Highlights of Astron. 3, 395) and by using limits derived from our own analysis. Spectroscopic data for the southern stars (Dec.<-30{deg}) in the PMSU survey are also presented. The data were combined with the data from paper I to obtain a list of all the magnetically active dMe stars in the survey.
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