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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.
| Magnitudes of selected stellar occultation candidates for Pluto and other planets, with new predictions for Mars and Jupiter
Occultation predictions for the planets Mars and Jupiter are presentedalong with BVRI magnitudes of 45 occultation candidates for Mars,Jupiter, Saturn, Uranus, and Pluto. Observers can use these magnitudesto plan observations of occultation events. The optical depth of theJovian ring can be probed by a nearly central occultation on 1992 July8. Mars occults an unusually red star in early 1993, and theoccultations for Pluto involving the brightest candidates would possiblyoccur in the spring of 1992 and the fall of 1993.
| Dwarf K and M stars of high proper motion found in a hemispheric survey
A recently completed visual/red spectral region objective-prism surveyof more than half the sky found some 2200 dwarf K and M stars ofnegligible proper motion (Stephenson, 1986). The present paper adds the1800-odd spectroscopically identified dwarfs that did prove to havesignificant proper motions. About half of these had previous spectralclassifications of some sort, especially by Vyssotsky (1952, 1956). Forthe great majority, the present coordinates are more accurate thanprevious data. The paper includes about 50 stars with unpublishedparallaxes, likely to have parallaxes of 0.05 arcsec or more. Combiningthe present data with the first paper suggests that the number oflow-proper-motion stars in that paper was not unreasonable.
| Dwarf K and M stars in the southern hemisphere.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972AJ.....77..486U&db_key=AST
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Basakci |
| Sað Açýklýk: | 12h25m51.03s |
| Yükselim: | -01°06'38.1" |
| Görünürdeki Parlaklýk: | 10.238 |
| Uzaklýk: | 38.402 parsek |
| özdevim Sað Açýklýk: | -311.3 |
| özdevim Yükselim: | -78 |
| B-T magnitude: | 11.978 |
| V-T magnitude: | 10.382 |
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