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Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| 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}
| POX 52: A Dwarf Seyfert 1 Galaxy with an Intermediate-Mass Black Hole
We describe new optical images and spectra of POX 52, a dwarf galaxywith an active nucleus that was originally detected in the POXobjective-prism survey. While POX 52 was originally thought to be aSeyfert 2 galaxy, the new data reveal an emission-line spectrum verysimilar to that of the dwarf Seyfert 1 galaxy NGC 4395, with broadcomponents to the permitted line profiles, and we classify POX 52 as aSeyfert 1 galaxy. The host galaxy appears to be a dwarf elliptical, andits brightness profile is best fit by a Sérsic model with anindex of 3.6+/-0.2 and a total magnitude of MV=-17.6.Applying mass-luminosity-line width scaling relations to estimate theblack hole mass from the broad Hβ line width and nonstellarcontinuum luminosity, we findMBH~1.6×105Msolar. The stellarvelocity dispersion in the host galaxy, measured from the Ca IIλ8498, 8542 lines, is 36+/-5 km s-1, also suggestiveof a black hole mass of order 105Msolar. Furthersearches for active nuclei in dwarf galaxies can provide uniqueconstraints on the demographics of black holes in the mass range below106Msolar.
| A Wide-Angle Astrometric Standard in the Moscow Zenith Zone
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| Stellar Spectra in Milky way REGIONS.III.A Region in Cepheus-Lacerta
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1955ApJS....2...75M&db_key=AST
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| Takýmyýldýz: | Kertenkele |
| Sað Açýklýk: | 22h13m03.61s |
| Yükselim: | +52°55'16.7" |
| Görünürdeki Parlaklýk: | 8.233 |
| Uzaklýk: | 381.679 parsek |
| özdevim Sað Açýklýk: | -32.9 |
| özdevim Yükselim: | 27.1 |
| B-T magnitude: | 9.763 |
| V-T magnitude: | 8.36 |
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