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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}
| 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.
| UBV photometry of stars whose positions are accurately known. VI
Results are presented from UBV photometric observations of 1000 stars ofthe Bright Star Catalogue and the faint extension of the FK5.Observations were carried out between July 1987 and December 1990 withthe 40-cm Cassegrain telescope of the Kvistaberg Observatory.
| Large and Kinematically Unbiased Samples of G- and K-Type Stars. III. Evolved Young Disk Stars in the Bright Star Sample
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1989PASP..101...54E&db_key=AST
| Large and kinematically unbiased samples of G- and K-type stars. II - Observations of evolved stars in the Bright Star sample. III - Evolved young disk stars in the Bright Star sample
Four color and RI observations were obtained for a large sample ofG-type and K-type stars in the Bright Star Catalogue. Data are firstpresented for 110 evolved stars. Photometry of evolved young diskpopulation stars have then been calibrated for luminosity, reddening,and metallicity on the basis of results for members of the Hyades andSirius superclusters. New DDO results are given for 120 stars.
| Spectroscopy and abundances of 88 K giants in Baade's Window
Spectroscopic and photometric observations of 122 stars in the Baade'sWindow region of the Galactic bulge (and of 63 K giant comparison starsin the Galactic disk and globular clusters), obtained using anintensified Reticon detector and a 600-line/mm 5000-A-blazed grating inthe Cassegrain spectrograph (spectral resolution 5 A) of the 2.5-mDuPont telescope at Las Campagnas Observatory during 1980-1984, arereported. The sample selection criteria and data-analysis techniques areexplained, and the data (including line strengths for 34 features andderived abundances for 88 K giants) are presented in extensive tablesand graphs and discussed in detail. It is concluded that the metalabundances in the nuclear-bulge strong-lined giants are significantlygreater than those of the metal-rich giants in the solar neighborhood.
| Photoelectric photometry of selected SAO stars. III
Photometric observations of 131 SAO stars for use in calibrating dataobtained from the Near Infrared Photographic Sky Survey (NIPSS) arereported. The serial numbers of the primary NIPSS program fields inwhich the photometry was done are shown along with the approximateposition of each field and the number of stars observed in each field.The observations are listed, showing the SAO numbers of the programstars, their 1950 equatorial coordinates, the V magnitudes, and the(V-R) and (V-I) color indices. The mean errors in magnitudes and colorindices obtained by averaging deviations from the mean for each star areon the order of 0.02 mag.
| Metal content of K giants in the nuclear bulge of the galaxy
The metallicity of 21 K giants in Baade's (1963) window has beendetermined by comparison of the strengths of strong iron lines and theMg b feature with those in 22 calibration stars having high-resolutionabundance analyses. The (J-K) colors were used to separate the effectsof temperature and metallicity on line strengths. The majority of thestars are super-metal-rich with a mean aggregate forbidden Fe/forbiddenH = 0.29 or 0.44 and an upper extreme forbidden Fe/forbidden H = 0.7 or1.0, depending on the method of extrapolation for stars more metal-richthan any solar neighborhood calibration stars. These values forindividual stars support the super-metal-rich explanation of very stronglines in the spectra of unresolved external galaxies. The minorityfraction of metal-poor stars, for which aggregate forbidden Fe/forbiddenH is about -1.0, includes the progenitors of Baade's RR Lyrae variables.The small-number statistics of the present sample leave the relativeproportion of the metal-poor stars and their possible status as aseparate group uncertain.
| Two-micron objects in the northern Monoceros region.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978PASJ...30..657I&db_key=AST
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Datos observacionales y astrométricos
| Constelación: | Unicornio |
| Ascensión Recta: | 06h37m36.90s |
| Declinación: | +10°51'11.0" |
| Magnitud Aparente: | 6.38 |
| Distancia: | 271.003 parsecs |
| Movimiento Propio en Ascensión Recta: | -39.2 |
| Movimiento Propio en Declinación: | -30.5 |
| B-T magnitude: | 8.15 |
| V-T magnitude: | 6.539 |
Catálogos y designaciones:
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