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Statistical Constraints for Astrometric Binaries with Nonlinear Motion
Useful constraints on the orbits and mass ratios of astrometric binariesin the Hipparcos catalog are derived from the measured proper motiondifferences of Hipparcos and Tycho-2 (Δμ), accelerations ofproper motions (μ˙), and second derivatives of proper motions(μ̈). It is shown how, in some cases, statistical bounds can beestimated for the masses of the secondary components. Two catalogs ofastrometric binaries are generated, one of binaries with significantproper motion differences and the other of binaries with significantaccelerations of their proper motions. Mathematical relations betweenthe astrometric observables Δμ, μ˙, and μ̈ andthe orbital elements are derived in the appendices. We find a remarkabledifference between the distribution of spectral types of stars withlarge accelerations but small proper motion differences and that ofstars with large proper motion differences but insignificantaccelerations. The spectral type distribution for the former sample ofbinaries is the same as the general distribution of all stars in theHipparcos catalog, whereas the latter sample is clearly dominated bysolar-type stars, with an obvious dearth of blue stars. We point outthat the latter set includes mostly binaries with long periods (longerthan about 6 yr).
| ROSAT High Resolution Imager Identifications of Suspected Stellar Sources from the Einstein Slew Survey
We present analysis of a series of ROSAT High Resolution Imager (HRI)observations of 16 X-ray detections from the Einstein Slew Survey (ESS).The data were taken to resolve ambiguous ESS identifications based onoptical spectroscopy. For 10 of the 16 detections, the previousidentification has been confirmed-six with solar-type stars (spectraltypes F-K), one each with a cataclysmic variable, a B2 V, a dMe star,and one with a BL Lac object. For another detection, two potentialcounterparts are unresolvable even with the HRI. The HRI does resolvetwo other ESS detections into two distinct X-ray sources, but no HRIsource is found for the remaining three X-ray detections. HRI-derivedfluxes are consistent with those measured by the ROSAT All-Sky Surveyfor their 12 common detections, and improved positions are obtained forthese sources. We calculate values of f_X/f_V and L_X for these starswhere possible and find values consistent with those expected forcorresponding spectral types.
| 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.
| The Einstein Slew Survey
A catalog of 819 sources detected in the Einstein IPC Slew Survey of theX-ray sky is presented; 313 of the sources were not previously known asX-ray sources. Typical count rates are 0.1 IPC count/s, roughlyequivalent to a flux of 3 x 10 exp -12 ergs/sq cm s. The sources havepositional uncertainties of 1.2 arcmin (90 percent confidence) radius,based on a subset of 452 sources identified with previously knownpointlike X-ray sources (i.e., extent less than 3 arcmin).Identifications based on a number of existing catalogs of X-ray andoptical objects are proposed for 637 of the sources, 78 percent of thesurvey (within a 3-arcmin error radius) including 133 identifications ofnew X-ray sources. A public identification data base for the Slew Surveysources will be maintained at CfA, and contributions to this data baseare invited.
| La mesure des vitesses radiales au prisme objectif - X - 4e liste de vitesses radiales déterminées au prisme objectif à vision directe
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| Takýmyýldýz: | Tekboynuz |
| Sað Açýklýk: | 06h43m26.89s |
| Yükselim: | +05°50'55.6" |
| Görünürdeki Parlaklýk: | 7.162 |
| Uzaklýk: | 294.118 parsek |
| özdevim Sað Açýklýk: | -17.9 |
| özdevim Yükselim: | -5.6 |
| B-T magnitude: | 8.429 |
| V-T magnitude: | 7.267 |
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