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A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)
The LSPM catalog is a comprehensive list of 61,977 stars north of theJ2000 celestial equator that have proper motions larger than 0.15"yr-1 (local-background-stars frame). The catalog has beengenerated primarily as a result of our systematic search for high propermotion stars in the Digitized Sky Surveys using our SUPERBLINK software.At brighter magnitudes, the catalog incorporates stars and data from theTycho-2 Catalogue and also, to a lesser extent, from the All-SkyCompiled Catalogue of 2.5 million stars. The LSPM catalog considerablyexpands over the old Luyten (Luyten Half-Second [LHS] and New LuytenTwo-Tenths [NLTT]) catalogs, superseding them for northern declinations.Positions are given with an accuracy of <~100 mas at the 2000.0epoch, and absolute proper motions are given with an accuracy of ~8 masyr-1. Corrections to the local-background-stars propermotions have been calculated, and absolute proper motions in theextragalactic frame are given. Whenever available, we also give opticalBT and VT magnitudes (from Tycho-2, ASCC-2.5),photographic BJ, RF, and IN magnitudes(from USNO-B1 catalog), and infrared J, H, and Ks magnitudes(from 2MASS). We also provide an estimated V magnitude and V-J color fornearly all catalog entries, useful for initial classification of thestars. The catalog is estimated to be over 99% complete at high Galacticlatitudes (|b|>15deg) and over 90% complete at lowGalactic latitudes (|b|>15deg), down to a magnitudeV=19.0, and has a limiting magnitude V=21.0. All the northern starslisted in the LHS and NLTT catalogs have been reidentified, and theirpositions, proper motions, and magnitudes reevaluated. The catalog alsolists a large number of completely new objects, which promise to expandvery significantly the census of red dwarfs, subdwarfs, and white dwarfsin the vicinity of the Sun.Based on data mining of the Digitized Sky Surveys (DSSs), developed andoperated by the Catalogs and Surveys Branch of the Space TelescopeScience Institute (STScI), Baltimore.Developed with support from the National Science Foundation (NSF), aspart of the NASA/NSF NStars program.
| 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 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.
| UBVRI photoelectric photometry of high proper motion stars
UBVRI photoelectric photometry is presented for 269 late spectral type,high proper motion stars belonging to the 'Lowell Proper Motion Survey'and included in the present version of the Hipparcos Input Catalogue.The observations and data reduction are described. The external errorsobtained by comparison of the results with those obtained in otherstudies are presented.
| Photometric parallaxes for selected stars of color class M from the NLTT catalog. III - The declination zone +20 deg to +45 deg
VRI photometry and photometric parallaxes are presented for a sample of787 late-type stars in the NLTT catalog for which no trigonometricparallaxes have been measured. Additional photometry of 108 stars withtrigonometric parallaxes is also presented. For the program stars, 131have pi(ph) of 0.04 arcsec or greater and six of these have pi(ph) of0.10 arcsec or greater. The percentage of subdwarfs among the stars thusfar surveyed is probably less than 3 percent.
| Spectral classification of high-proper-motion stars
Spectral types have been found for about 900 stars of high proper motioncontained in the Lowell Observatory Northern Hemisphere proper-motionstar survey using all blue-region objective prism plates. The spectralclassification criteria are given. About eighty stars of largetangential velocity have been classified using slit spectrograms takenwith a 36-in. reflector. A new calibration of Luyten's absolutemagnitude vs reduced proper motion relation is made, and its dependenceon spectral type is investigated.
| Lowell proper motions II : proper motion survey of the Northern Hemisphere with the 13-inch photographic telescope of the Lowell Observatory
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| 별자리: | 양자리 |
| 적경: | 02h55m41.25s |
| 적위: | +28°07'47.6" |
| 가시등급: | 11.081 |
| 거리: | 36.271 파섹 |
| 적경상의 고유운동: | 269.6 |
| 적위상의 고유운동: | -144.3 |
| B-T magnitude: | 12.771 |
| V-T magnitude: | 11.221 |
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