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Improved Astrometry and Photometry for the Luyten Catalog. II. Faint Stars and the Revised Catalog
We complete construction of a catalog containing improved astrometry andnew optical/infrared photometry for the vast majority of NLTT starslying in the overlap of regions covered by POSS I and by the secondincremental Two Micron All Sky Survey (2MASS) release, approximately 44%of the sky. The epoch 2000 positions are typically accurate to 130 mas,the proper motions to 5.5 mas yr-1, and the V-J colors to0.25 mag. Relative proper motions of binary components are measured to 3mas yr-1. The false-identification rate is ~1% for11<~V<~18 and substantially less at brighter magnitudes. Theseimprovements permit the construction of a reduced proper-motion diagramthat, for the first time, allows one to classify NLTT stars intomain-sequence (MS) stars, subdwarfs (SDs), and white dwarfs (WDs). We inturn use this diagram to analyze the properties of both our catalog andthe NLTT catalog on which it is based. In sharp contrast to popularbelief, we find that NLTT incompleteness in the plane is almostcompletely concentrated in MS stars, and that SDs and WDs are detectedalmost uniformly over the sky δ>-33deg. Our catalogwill therefore provide a powerful tool to probe these populationsstatistically, as well as to reliably identify individual SDs and WDs.
| The Palomar/MSU Nearby Star Spectroscopic Survey.II.The Southern M Dwarfs and Investigation of Magnetic Activity
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996AJ....112.2799H&db_key=AST
| The Palomar/MSU Nearby-Star Spectroscopic Survey. I. The Northern M Dwarfs -Bandstrengths and Kinematics
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....110.1838R&db_key=AST
| The luminosity function at the end of the main sequence: Results of a deep, large-area, CCD survey for cool dwarfs
The luminosity function at the end of the main sequence is determinedfrom V, R, and I data taken by the charge coupled devices (CCD)/TransitInstrument, a dedicated telescope surveying an 8.25 min wide strip ofsky centered at delta = +28 deg, thus sampling Galactic latitudes of +90deg down to -35 deg. A selection of 133 objects chosen via R - I and V -I colors has been observed spectroscopically at the 4.5 m MultipleMirror Telescope to assess contributions by giants and subdwarfs and toverify that the reddest targets are objects of extremely late spectralclass. Eighteen dwarfs of type M6 or later have been discovered, withthe latest being of type M8.5. Data used for the determination of theluminosity function cover 27.3 sq. deg down to a completeness limit of R= 19.0. This luminosity function, computed at V, I, and bolometricmagnitudes, shows an increase at the lowest luminosities, correspondingto spectral types later than M6- an effect suggested in earlier work byReid & Gilmore and Legget & Hawkins. When the luminosityfunction is segregated into north Galactic and south Galactic portions,it is found that the upturn at faint magnitudes exists only in thesouthern sample. In fact, no dwarfs with MI is greater thanor equal to 12.0 are found within the limiting volume of the 19.4 sq degnorthern sample, in stark contrast to the smaller 7.9 sq deg area atsoutherly latitudes where seven such dwarfs are found. This fact,combined with the fact that the Sun is located approximately 10-40 pcnorth of the midplane, suggests that the latest dwarfs are part of ayoung population with a scale height much smaller than the 350 pc valuegenerally adopted for other M dwarfs. These objects comprise a youngpopulation either because the lower metallicities prevelant at earlierepochs inhibited the formation of late M dwarfs or because the oldercounterparts of this population have cooled beyond current detectionlimits. The latter scenario would hold if these late-type M dwarfs aresubstellar. The luminosity function data together with an empiricalderivation of the mass-luminosity relation (from Henry & McCarthy)are used to compute a mass function independent of theory. This massfunction increases toward the end of the main sequence, but the observeddensity of M dwarfs is still insufficient to account for the missingmass. If the increases seen in the luminosity and mass functions areindicative of a large, unseen, substellar population, brown dwarfs mayyet add significantly to the mass of the Galaxy.
| Preliminary Version of the Third Catalogue of Nearby Stars
Not Available
| New subdwarfs. IV - UBV photometry of 1690 high-proper-motion stars
A photometric list of 1690 stars of known high proper motion is used tosearch for potential high-velocity stars of various metallicity valuesin order to find candidates for trigonometric programs on subdwarfs andto enlarge the sample with which to study the relation between stellarkinematics and metal abundance. A list of 113 stars with tangentialspace velocities of 300 km/s or greater is obtained, the highesttangential velocity relative to the sun being 630 km/s. By using thevariation of the tangential velocity with longitude and adopting thegalactic rotation at the solar circle to be 220 km/s, the rotation ofthe subdwarf system is estimated at 0 + or - 50 km/s from the transversevelocity alone, in agreement with determinations based on other methods.
| G. P. Kuiper's spectral classifications of proper-motion stars
Spectral classifications are listed for over 3200 stars, mainly of largeproper motion, observed and classified by Kuiper during the years1937-1944 at the Yerkes and McDonald Observatories. While Kuiper himselfpublished many of his types, and while improved classifications are nowavailable for many of these stars, much of value remains. For many ofthe objects, no other spectral data exist.
| Spectral types for proper motion stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975AJ.....80..239B&db_key=AST
| Lowell proper motions III : proper motion survey of the Northern Hemisphere with the 13-inch photographic telescope of the Lowell Observatory
Not Available
| New proper-motion stars, (fourth list)
Not Available
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