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Sixth Catalogue of Fundamental Stars (FK6). Part III. Additional fundamental stars with direct solutions
The FK6 is a suitable combination of the results of the HIPPARCOSastrometry satellite with ground-based data, measured over a longinterval of time and summarized mainly in the FK5. Part III of the FK6(abbreviated FK6(III)) contains additional fundamental stars with directsolutions. Such direct solutions are appropriate for single stars or forobjects which can be treated like single stars. Part III of the FK6contains in total 3272 stars. Their ground-based data stem from thebright extension of the FK5 (735 stars), from the catalogue of remainingSup stars (RSup, 732 stars), and from the faint extension of the FK5(1805 stars). From the 3272 stars in Part III, we have selected 1928objects as "astrometrically excellent stars", since their instantaneousproper motions and their mean (time-averaged) ones do not differsignificantly. Hence most of the astrometrically excellent stars arewell-behaving "single-star candidates" with good astrometric data. Thesestars are most suited for high-precision astrometry. On the other hand,354 of the stars in Part III are Δμ binaries in the sense ofWielen et al. (1999). Many of them are newly discovered probablebinaries with no other hitherto known indication of binarity. The FK6gives, besides the classical "single-star mode" solutions (SI mode),other solutions which take into account the fact that hidden astrometricbinaries among "apparently single-stars" introduce sizable "cosmicerrors" into the quasi-instantaneously measured HIPPARCOS proper motionsand positions. The FK6 gives, in addition to the SI mode, the "long-termprediction (LTP) mode" and the "short-term prediction (STP) mode". TheseLTP and STP modes are on average the most precise solutions forapparently single stars, depending on the epoch difference with respectto the HIPPARCOS epoch of about 1991. The typical mean error of anFK6(III) proper motion in the single-star mode is 0.59 mas/year. This isa factor of 1.34 better than the typical HIPPARCOS errors for thesestars of 0.79 mas/year. In the long-term prediction mode, in whichcosmic errors are taken into account, the FK6(III) proper motions have atypical mean error of 0.93 mas/year, which is by a factor of about 2better than the corresponding error for the HIPPARCOS values of 1.83mas/year (cosmic errors included).
| The Optical Gravitational Lensing Experiment. UBVI Photometry of Stars in Baade's Window
We present UBVI photometry for 8530 stars in Baade's Window obtainedduring the OGLE-II microlensing survey. Among these are over onethousand red clump giants. 1391 of them have photometry with errorssmaller than 0.04, 0.06, 0.12, and 0.20 mag in the I, V, B, and U-band,respectively. We constructed a map of interstellar reddening. Thecorrected colors of the red clump giants: (U-B)_0, (B-V)_0, and (V-I)_0are very well correlated, indicating that a single parameter determinesthe observed spread of their values, reaching almost 2 mag in the(U-B)_0. It seems most likely that heavy element content is the dominantparameter, but it is possible that another parameter: the age (or mass)of a star moves it along the same trajectory in the color-color diagramas the metallicity. The current ambiguity can be resolved with spectralanalysis, and our catalog may be useful as a finding list of red clumpgiants. We point out that these K giants are more suitable for a fairdetermination of the distribution of metallicity than brighter M giants.We also present a compilation of UBVI data for 308 red clump giants nearthe Sun, for which Hipparcos parallaxes are more accurate than 10%.Spectral analysis of their metallicity may provide information about thelocal metallicity distribution as well as the extent to which mass (age)of these stars affects their colors. It is remarkable that in spite of anumber of problems, stellar models agree with observations at the0.1-0.2 mag level, making red clump giants not only the best calibratedbut also the best understood standard candle.
| Improved Mean Positions and Proper Motions for the 995 FK4 Sup Stars not Included in the FK5 Extension
Not Available
| UBVRI photometry of FK4 and FK4 supplement stars
Photometric UBVRI observations of 172 Southern Hemisphere stars of theFK4 and FK4-Supplement catalogs, obtained using a dry-ice-cooledphotomultiplier on the 50-cm telescope at ESO on 37 nights during1982-1983 are reported. The data are presented in tables and graphs andbriefly characterized.
| Hyades and Sirius supercluster members brighter than magnitude (V) 7.1. II - Right ascension six to twelve hours
The present star sample is contained in the Bright Star Catalogue andits Supplement, augmented with a further supplement of 788 stars foundduring various observing programs over the past 40 years. Accurate,four-color and H-beta, or (RI), photometry is available for most of thesupercluster members. The criteria for membership are the comparisons ofthe proper motion, radial velocity, and luminosity obtained from thesupercluster parameters with the observed motions and the luminosityderived from the photometric parameters. New proper motions, based onall available catalogs, have been derived for the additional 788 starsdiscussed here, as well as all supercluster members.
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| Takýmyýldýz: | Ucan Balik |
| Sað Açýklýk: | 08h44m42.75s |
| Yükselim: | -74°47'16.9" |
| Görünürdeki Parlaklýk: | 6.659 |
| Uzaklýk: | 124.533 parsek |
| özdevim Sað Açýklýk: | -4 |
| özdevim Yükselim: | 11.6 |
| B-T magnitude: | 8.238 |
| V-T magnitude: | 6.79 |
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