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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}
| Multi-colour light variation of AGB stars observed with ISO
New visual light curves and infrared multi-epoch photometry arepresented for a sample of AGB-stars spectroscopically observed with ISO.While the ISO work is or will be presented elsewhere, the aim of thispaper is to give an overview of the properties of the light change ofthe objects. This information is crucial for the interpretation of thevaluable ISO material. Using the University of Vienna Twin AutomaticPhotoelectric Telescope (APT) we monitored the stars of our sample inthe photometric bands V and I_C. We present the light curve of eachobject and derive the parameters of the current light change, such asperiod(s) and amplitude. Furthermore we give V-I_C colours and colourvariations for these objects. Our results allow us to derive somegeneral results on semiregular and irregular variables. Only in lessthan 50% of the cases could we confirm the GCVS period. Moreover, we didnot find any pronounced difference between SRb and Lb variables in theregularity of the light curve. The existence of rapid oscillationsindicated by Hipparcos data could not be confirmed. In addition to thevisual light changes we present new near infrared photometry data.Although typically only few data points are available, they can beviewed relative to the better-monitored visual light curves providinginformation on possible phase shifts and differences in amplitude indifferent parts of the spectrum. Furthermore, multi-epoch photometryallows us to derive mean colours for these objects. Based onobservations made with the Carlos Sánchez Telescope operated onthe island of Tenerife by the Instituto de Astrofísica deCanarias (IAC) in the Observatorio del Teide, Izaña. Tables B2 toB5 are only available in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/375/527
| 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 velocities of certain stars previously measured at the David Dunlap Observatory
Not Available
| Accuracy of two-dimensional spectral classes derived through DDO photometry.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977AJ.....82..832Y&db_key=AST
| Photoelectric photometry of selected AG stars in the 25D to 30D zone.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968AJ.....73..187B&db_key=AST
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Группы:
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Наблюдательные данные и астрометрия
| Созвездие: | Волопас |
| Прямое восхождение: | 14h25m54.58s |
| Склонение: | +26°15'55.0" |
| Видимая звёздная величина: | 7.437 |
| Расстояние: | 204.082 парсек |
| Собственное движение RA: | -60.5 |
| Собственное движение Dec: | -35.2 |
| B-T magnitude: | 9.161 |
| V-T magnitude: | 7.58 |
Каталоги и обозначения:
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