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Kinematics of Hipparcos Visual Binaries. II. Stars with Ground-Based Orbital Solutions
This paper continues kinematical investigations of the Hipparcos visualbinaries with known orbits. A sample, consisting of 804 binary systemswith orbital elements determined from ground-based observations, isselected. The mean relative error of their parallaxes is about 12% andthe mean relative error of proper motions is about 4%. However, even 41%of the sample stars lack radial velocity measurements. The computedGalactic velocity components and other kinematical parameters are usedto divide the stars with known radial velocities into kinematical agegroups. The majority (92%) of binaries from the sample are thin diskstars, 7.6% have thick disk kinematics and only two binaries have halokinematics. Among them, the long-period variable Mira Ceti has a verydiscordant {Hipparcos} and ground-based parallax values. From the wholesample, 60 stars are ascribed to the thick disk and halo population.There is an urgent need to increase the number of the identified halobinaries with known orbits and substantially improve the situation withradial velocity data for stars with known orbits.
| Photographic astrometry of binary and proper-motion stars
Plate series obtained at the 61-cm Sproul refractor of SwarthmoreCollege were processed during the time October 1982 to December 1983.Parts of some plate series had been measured previously. The presentinvestigation involves an evaluation of the entire material, taking intoaccount 58 trigonometric parallaxes and 14 binary-star mass ratios.Table I lists the parallax results. The measured components of theannual motion are to three decimals of arc seconds. A summary of themass-ratio results is provided in a second table. All observed objectsare briefly discussed.
| Some enigmatic binary stars. I
Historical measurements of components of binary star systems at timesexhibit evidence for incompatible interpretations. A short period andstrong eccentricity can equally be a long period with feebleeccentricity. Furthermore, measurements have been made indicating bothdirect and retrograde motions of the components. It has sometimes beenfound that the observations of contradicting evidence have been made ofa second binary system near the system first measured. Note is taken ofthe objects ADS 1959 - A 1818, ADS 2051 - HU 539, ADS 5515 - A 512, ADS5671 - BU 1022, ADS 6001 - A 1963, and ADS 7550 - A 2561, which maypossibly be combinations of two or even three binary clusters observedat different times. Tables are presented of data thus far measured ofeach system.
| Mesures d'étoiles doubles faites au réfracteur de 38 cm de l'Observatoire de Nice
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