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מאמרים קשורים
Improvement of Hipparcos Proper Motions in Declination
More than a decade elapsed after the HIPPARCOS ESA mission (ESA 1997)observations have been collected. This first astronomical satellitemission was less than 4 years long so that 1991.25 is the epoch of theHIPPARCOS Catalogue. Many other projects have checked or improvedHIPPARCOS data. Also, a long series of ground - based opticalobservations of some stars included in HIPPARCOS Catalogue, made withPhotographic Zenith Tubes (PZT) are useful for the task of improving theproper motions of these stars. The ARIHIP Catalogue (after ACT, TYCHO -2, FK6, GC+HIP, TYC2+HIP) is a combination of the HIPPARCOS and someground - based data, and the ARIHIP proper motions are more accuratethan the HIPPARCOS ones. Here we present a new step of our procedure ofcalculation; between PZT data we added the HIPPARCOS position withsuitable weight - the point with the coordinates (1991.25, 0ŭ0)in our case. The method was applied to 202 stars observed at RichmondPZTs in the course of a few decades. The result is better proper motionsin declination for these HIPPARCOS stars, and a good agreement withARIHIP proper motions (we found 128 common Richmond and ARIHIP stars tocheck our result). Also, we present the result for other 74 Richmondstars which are not found in ARIHIP.
| Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters
The availability of the Hipparcos Catalogue has triggered many kinematicand dynamical studies of the solar neighbourhood. Nevertheless, thosestudies generally lacked the third component of the space velocities,i.e., the radial velocities. This work presents the kinematic analysisof 5952 K and 739 M giants in the solar neighbourhood which includes forthe first time radial velocity data from a large survey performed withthe CORAVEL spectrovelocimeter. It also uses proper motions from theTycho-2 catalogue, which are expected to be more accurate than theHipparcos ones. An important by-product of this study is the observedfraction of only 5.7% of spectroscopic binaries among M giants ascompared to 13.7% for K giants. After excluding the binaries for whichno center-of-mass velocity could be estimated, 5311 K and 719 M giantsremain in the final sample. The UV-plane constructed from these datafor the stars with precise parallaxes (σπ/π≤20%) reveals a rich small-scale structure, with several clumpscorresponding to the Hercules stream, the Sirius moving group, and theHyades and Pleiades superclusters. A maximum-likelihood method, based ona Bayesian approach, has been applied to the data, in order to make fulluse of all the available stars (not only those with precise parallaxes)and to derive the kinematic properties of these subgroups. Isochrones inthe Hertzsprung-Russell diagram reveal a very wide range of ages forstars belonging to these groups. These groups are most probably relatedto the dynamical perturbation by transient spiral waves (as recentlymodelled by De Simone et al. \cite{Simone2004}) rather than to clusterremnants. A possible explanation for the presence of younggroup/clusters in the same area of the UV-plane is that they have beenput there by the spiral wave associated with their formation, while thekinematics of the older stars of our sample has also been disturbed bythe same wave. The emerging picture is thus one of dynamical streamspervading the solar neighbourhood and travelling in the Galaxy withsimilar space velocities. The term dynamical stream is more appropriatethan the traditional term supercluster since it involves stars ofdifferent ages, not born at the same place nor at the same time. Theposition of those streams in the UV-plane is responsible for the vertexdeviation of 16.2o ± 5.6o for the wholesample. Our study suggests that the vertex deviation for youngerpopulations could have the same dynamical origin. The underlyingvelocity ellipsoid, extracted by the maximum-likelihood method afterremoval of the streams, is not centered on the value commonly acceptedfor the radial antisolar motion: it is centered on < U > =-2.78±1.07 km s-1. However, the full data set(including the various streams) does yield the usual value for theradial solar motion, when properly accounting for the biases inherent tothis kind of analysis (namely, < U > = -10.25±0.15 kms-1). This discrepancy clearly raises the essential questionof how to derive the solar motion in the presence of dynamicalperturbations altering the kinematics of the solar neighbourhood: doesthere exist in the solar neighbourhood a subset of stars having no netradial motion which can be used as a reference against which to measurethe solar motion?Based on observations performed at the Swiss 1m-telescope at OHP,France, and on data from the ESA Hipparcos astrometry satellite.Full Table \ref{taba1} is only available in electronic form at the CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/430/165}
| 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.
| Visual multiples. VIII - 1000 MK types
A total of 1000 new classifications are given for stars brighter than B= 8.0 mag in the Aitken double star catalog. The classificationssupplement 865 classifications obtained in 1981 and 1984. Among thenewly discovered stars are 12 new Ap stars, eight Lambda Bootis stars,one Ba II star, and 60 Am stars. A detailed list of the newclassifications is given.
| Cataloged infrared sources in NIPSS data. I - The RSO 1 catalog
A small number of selected near-infrared and visual photographic pairsfrom the Steward Observatory Near Infrared Photographic Sky Survey havebeen examined for content of stars more red than (V-I) of about 2.5magnitudes. A simple manual extraction of these objects was carried outas a part of a preliminary evaluation of survey data and techniques forreducing it; the resulting list has been compiled as the firstinstallment of a Catalog of Red Stellar Objects (Craine et al. 1979).Results of a cross correlation of this catalog with the IRC, AFGL, andEIC infrared catalogs are here presented. The results indicate thatthese photographs may be particularly useful for purposes of opticalidentification of short-wavelength infrared sources to limits muchfainter than represented by presently existing infrared catalogs.
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | פגסוס |
| התרוממות ימנית: | 23h22m28.58s |
| סירוב: | +25°55'06.5" |
| גודל גלוי: | 6.373 |
| מרחק: | 331.126 פארסק |
| תנועה נכונה: | 2.4 |
| תנועה נכונה: | -11.3 |
| B-T magnitude: | 8.404 |
| V-T magnitude: | 6.541 |
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