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Kinematics and Luminosity Function of Dwarf Populations in Three Areas of the Calán-ESO Proper-Motion Catalog
We have completed the analysis of a sample of 112 stars in the solarneighborhood taken from the statistically complete Calán-ESOcatalog. From medium-resolution spectroscopy we classified every star,both by direct comparison with spectroscopic standards and by usingspectral indices. The latter also allowed discrimination betweenmain-sequence (MS) dwarfs and subdwarfs. Several useful spectral typeversus color relations were obtained from CCD photometry of the sample(observed magnitudes were dereddened). Distances and absolute magnitudeswere determined. From measured radial velocities and proper motions, wedetermined the kinematics [Galactocentric velocity components (U,V,W)],which allowed the classification of each star as belonging to the diskor halo population. Luminosity functions (LFs) were then obtained usingthe 1/Vmax method for the different populations. The maximumin the LF for MS dwarfs was found to be near MV=12.5+/-0.5,in accord with previous determinations. On the other hand, we found anincrease in the LF of the subdwarf at its faint end, which is in strongdisagreement with determinations by other authors. A mass density of MSdwarfs of ~0.047+/-0.021 Msolar pc-3 was derived,while the contribution of subdwarfs was found to be negligible.Based on observations obtained with the VLT (ESO), project 67.D-0224A.
| 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.
| Calán-ESO Proper-Motion Catalog
The Calán-ESO Proper-Motion Catalog (CE Catalog) contains 542stars with proper motions >=0.2" yr-1, identified in 14ESO areas in the southern hemisphere. Proper motions were measured fromred IIIa-F plates taken 6-16 yr apart. Comparing the CE catalog with theLuyten and the Luyten half-second catalogs, we find that both sufferfrom incompleteness, which is particularly serious (<~40% complete)for mR>~13, where many of the astrophysically interestingobject can be found. Proper motions, coordinates, estimated magnitudes,and finding charts for all objects in the catalog are provided. Based onplates obtained with the Schmidt Camera operated by ESO at La Silla,Chile. Project 64.H-0318.
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Osservazione e dati astrometrici
| Costellazione: | Centauro |
| Ascensione retta: | 14h23m57.72s |
| Declinazione: | -35°29'50.7" |
| Magnitudine apparente: | 9.95 |
| Moto proprio RA: | -67.9 |
| Moto proprio Dec: | -146.7 |
| B-T magnitude: | 10.818 |
| V-T magnitude: | 10.022 |
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