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Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| High-precision time-resolved CCD photometry
High-precision time-resolved photometry and detection of low-amplitudestellar oscillations are limited in precision by many factors. The noiseterms for a typical time-series observation contain observational noiseand errors as well as instrumental noise and reduction noise. This paperdescribes some of the problems related to high-precision photometry,especially focusing on CCD photometry both on focused stars (in semi-and noncrowded fields) and defocused field stars. It is shown thatatmospheric transparency variations and instrumental drift are the mainnoise sources at low frequencies (below 1-2 mHz), and that CCDphotometry is the best way of doing differential measurements in orderto detect oscillations at low frequencies. The theoretical descriptionof noise and problems in high-precision photometry is compared with CCDtime-series observations in a noncrowded test field observed with theDanish 1.5-m telescope at ESO La Silla, Chile in 1990. In addition,observations of defocused double stars observed with the Nordic OpticalTelescope in 1991 are described.
| A sample of solar-type stars of known age
A sample of field F and G dwarfs of known ages is presented. All thedwarfs are secondaries of visual binaries in which the temperature andgravity of the hotter primary has been estimated from Stromgrenphotometry, and its age derived from reference to isochrones. This ageis taken to apply to the secondary. Even in the case of F-typesecondaries, which themselves have measured Stromgren indices, it ismuch better to estimate ages from the primaries as it is demonstratedthat use of isochrones to determine age of stars not far evolved fromthe main sequence can lead to significant systematic overestimates ofages when the photometric measurements have typical random errors. Anumber of systems in which photometry is available for both componentshave primaries which appear much younger than the secondaries,suggesting a need for further investigation.
| Estimation of spectral classifications for bright northern stars with interesting Stromgren indices
The purpose of this investigation is to provide spectroscopic observerswith finding lists of potentially interesting objects. From anunpublished UVBY catalogue of 7026 northern stars (mostly brighter than8.3m) 1094 objects with interesting combinations of UVBY indices havebeen selected. Most stars with post-HD classifications have beenexcluded, as well as late F dwarfs belonging to the intermediatepopulation II. For the 792 remaining stars estimated spectralclassifications are given. The techniques and experience from a previouspaper dealing with southern stars have been utilized here. Among thepredicted spectral classifications are 40 OB stars; 262 Ap, Am, or Fmstars; 16 supergiants of types A to G; 110 bright giants of types A to K(class II); 156 double stars or objects with composite spectra; 26 lateF dwarfs; 91 weak-lined dwarf and giant stars of types F to K, includingearly F-type population II field blue stragglers; and a few possiblefield horizontal branch stars, lambda Bootis-type stars, and late-typehalo giants.
| UVBY Bet study of A-and F-type visual binaries. II.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978AJ.....83.1646M&db_key=AST
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Pozíciós és asztrometriai adatok
| Csillagkép: | Ökörhajcsár |
| Rektaszcenzió: | 13h50m20.60s |
| Deklináció: | +21°15'20.2" |
| Vizuális fényesség: | 7.276 |
| Távolság: | 110.132 parszek |
| RA sajátmozgás: | -35.9 |
| Dec sajátmozgás: | 16.5 |
| B-T magnitude: | 8.421 |
| V-T magnitude: | 7.371 |
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