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The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of 14 000 F and G dwarfs
We present and discuss new determinations of metallicity, rotation, age,kinematics, and Galactic orbits for a complete, magnitude-limited, andkinematically unbiased sample of 16 682 nearby F and G dwarf stars. Our63 000 new, accurate radial-velocity observations for nearly 13 500stars allow identification of most of the binary stars in the sampleand, together with published uvbyβ photometry, Hipparcosparallaxes, Tycho-2 proper motions, and a few earlier radial velocities,complete the kinematic information for 14 139 stars. These high-qualityvelocity data are supplemented by effective temperatures andmetallicities newly derived from recent and/or revised calibrations. Theremaining stars either lack Hipparcos data or have fast rotation. Amajor effort has been devoted to the determination of new isochrone agesfor all stars for which this is possible. Particular attention has beengiven to a realistic treatment of statistical biases and errorestimates, as standard techniques tend to underestimate these effectsand introduce spurious features in the age distributions. Our ages agreewell with those by Edvardsson et al. (\cite{edv93}), despite severalastrophysical and computational improvements since then. We demonstrate,however, how strong observational and theoretical biases cause thedistribution of the observed ages to be very different from that of thetrue age distribution of the sample. Among the many basic relations ofthe Galactic disk that can be reinvestigated from the data presentedhere, we revisit the metallicity distribution of the G dwarfs and theage-metallicity, age-velocity, and metallicity-velocity relations of theSolar neighbourhood. Our first results confirm the lack of metal-poor Gdwarfs relative to closed-box model predictions (the ``G dwarfproblem''), the existence of radial metallicity gradients in the disk,the small change in mean metallicity of the thin disk since itsformation and the substantial scatter in metallicity at all ages, andthe continuing kinematic heating of the thin disk with an efficiencyconsistent with that expected for a combination of spiral arms and giantmolecular clouds. Distinct features in the distribution of the Vcomponent of the space motion are extended in age and metallicity,corresponding to the effects of stochastic spiral waves rather thanclassical moving groups, and may complicate the identification ofthick-disk stars from kinematic criteria. More advanced analyses of thisrich material will require careful simulations of the selection criteriafor the sample and the distribution of observational errors.Based on observations made with the Danish 1.5-m telescope at ESO, LaSilla, Chile, and with the Swiss 1-m telescope at Observatoire deHaute-Provence, France.Complete Tables 1 and 2 are only available in electronic form at the CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/989
| 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.
| On the multiperiodicity of the δ Scuti star BDS 1269A (VW Arietis). The fifth campaign of STEPHI network in 1993.
This paper reports on the fifth STEPHI multi-site photometric campaignin 1993 devoted to the δ Scuti star BDS 1269A (VW Ari). Theobservation yielded a data set of 150.7 hours. Our analysis has resultedin 7 identified frequencies. These frequencies exhibit threecouple-frequency character, and also fit the previous investigationsquite well. An attempt to identify the pulsation modes is made, but noequidistant evidence can be detected, and a second-order effect forrotational splitting has to be considered to explain the complicatednature of BDS 1269A.
| Stroemgren photometry of F- and G-type stars brighter than V = 9.6. I. UVBY photometry
Within the framework of a large photometric observing program, designedto investigate the Galaxy's structure and evolution, Hβ photometryis being made for about 9000 stars. As a by-product, supplementary uvbyphotometry has been made. The results are presented in a cataloguecontaining 6924 uvby observations of 6190 stars, all south ofδ=+38deg. The overall internal rms errors of one observation(transformed to the standard system) of a program star in the interval6.5
| Multiple Frequencies Pulsation of the Delta-Scuti Variable BDS:1269A
Not Available
| KPNO lunar occultation summary. I
The results of a program to photoelectrically record lunar occultationsat KPNO are described. The program emphasizes the observation of knownor suspected double/multiple stars as well as the observation of starswith resolvable angular diameters.
| Photoelectric observations of lunar occultations. XI
Occultation observations of 466 events are presented. These includediameter measures of Aldebaran under very bad conditions and a gooddiameter measure of 82 Vir. The list includes 91 reappearances andobservations of 34 double or multiple stars, both new and previouslyknown. The inconsistencies of the observations of Kui 88 are discussed.Further observations are most desirable.
| The unique visual binary BDS 1269
Results are reported for uvby photoelectric photometry of the unusualvisual binary BDS 1269, whose components strongly differ in metalabundance. It is found that the metal-deficient primary, HD 15165,pulsates in a beat mode, that the largest amplitude is greater than 0.12mag, and that the primary period is about 0.16 day. The absolute visualmagnitude of HD 15165 is estimated to be approximately 0.9. The resultsindicate that HD 15165 has the luminosity and pulsational properties ofa Delta Scuti-type star or (less likely) a dwarf Cepheid. The origin ofthe binary system is briefly considered.
| Observations of BDS 1269, a metal-deficient del SCT star.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976PASP...88..251S&db_key=AST
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Observation and Astrometry data
| Constellation: | Κριός |
| Right ascension: | 02h26m11.09s |
| Declination: | +10°38'16.1" |
| Apparent magnitude: | 7.325 |
| Proper motion RA: | 83.7 |
| Proper motion Dec: | -257.1 |
| B-T magnitude: | 8.003 |
| V-T magnitude: | 7.381 |
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