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UvbyHbeta_ photometry of main sequence A type stars.
We present Stroemgren uvby and Hbeta_ photometry for a set of575 northern main sequence A type stars, most of them belonging to theHipparcos Input Catalogue, with V from 5mag to 10mag and with knownradial velocities. These observations enlarge the catalogue we began tocompile some years ago to more than 1500 stars. Our catalogue includeskinematic and astrophysical data for each star. Our future goal is toperform an accurate analysis of the kinematical behaviour of these starsin the solar neighbourhood.
| 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.
| Radial-velocity measurements. V - Ground support of the HIPPARCOS satellite observation program
The paper presents data on 1070 radial velocity measurements of starsdistributed in 39 fields measuring 4 deg x 4 deg. The PPO series ofFehrenbach et al. (1987) and Duflot et al. (1990) is continued using theFehrenbach objective prism method.
| The distribution of periods of the magnetic A-type stars
Four-color (uvby) photoelectric observations are used to obtain periodsfor several Ap stars with v sin i less than 10 km/sec. The derivedperiods are 69.0 days for HD 5797, 10.61 days for HD 22374, 69 days forHT 3724, and 5.07 days for HD 115708. The magnetic field strengthsmeasured from Zeeman spectrograms of 33 Lib vary with a period of 23.26days. Photoelectric and Zeeman spectroscopic observations yield a periodof 525 days for HD 2453. Evidence is given that suggests that HR 4816may vary on a time scale of 10 years. The present observations, combinedwith results published previously, make it possible to derive thedistribution of periods for the cool (non-Si) Ap-type stars. It isargued that the data support the hypothesis that the period of variationis to be identified in all cases with the period of rotation, and thatthe existence of Ap stars with extremely long periods is due to the lossof angular momentum through some form of magnetic braking.
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