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Pulkovo compilation of radial velocities for 35495 stars in a common system.
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| Circumnuclear structure and kinematics in the active galaxy NGC 6951
A study is presented of the central structure and kinematics of thegalaxy NGC 6951, by means of broad band B{\arcminIJK} images and highresolution high dispersion longslit spectroscopy, together with archivalHST WFPC2 V and NICMOS2 J and H images. We find that there is littleongoing star formation inside the bar dominated region of the galaxy,except for the circumnuclear ring at 5 arcsec radius. There is someevidence that this star formation occurs in two modes, in bursts andcontinuously, along the ring and inwards, towards the nucleus. Theequivalent width of the Ca Ii triplet absorption lines show that, in themetal rich central region, the continuum is dominated by a population ofred supergiants, while red giants dominate outside. The gaseouskinematics along three slit position angles, and the comparison with thestellar kinematics, suggest the existence of a hierarchy of disks withindisks, whose dynamics are decoupled at the two inner Linblad resonances(ILR), that we find to be located at 180 pc and at 1100 pc. This issupported by the structure seen in the high resolution HST images. Thenucleus is spatially resolved in the emission line ratio [N Ii]/Hα, and in the FWHM of the emission lines, within a radius of1.5{\arcsec}, just inside the innermost ILR. Outside the iILR, thestellar CaT velocity profile is resolved into two different components,associated with the bar and the disk. Several results indicate that thisis a dynamically old system: the little ongoing star formation insidethe bar dominated part of the galaxy, the very large relative amount ofmolecular to total mass within the inner 6 arcsec radius, ~ 25%, and thegeometry of the circumnuclear ring that leads the stellar bar at aposition angle greater than 90°. It is thus possible that a nuclearbar has existed in NGC 6951 that drove the gas towards the nucleus, asin the bars within bars scenario, but that this bar has alreadydissolved by the gas accumulated within the circumnuclear region. Wediscuss the possibility that the kinematical component inside the iILRcould be due to a nuclear outflow produced by the combined effects of SNand SN remnants, or to a nuclear disk, as in the disk within diskscenario that we propose for the fueling of the AGN in NGC 6951. Basedon observations made with the 4.2m William Herschel Telescope operatedby the Isaac Newton Group, and the 2.6m Nordic Optical Telescopeoperated jointly by Denmark, Finland, Iceland, Norway, and Sweden, onthe island of La Palma in the Spanish Observatorio del Roque de losMuchachos of the Instituto de Astrofísica de Canarias. Also basedon observations made with the NASA/ESA Hubble Space Telescope, obtainedfrom the data archive at the ESA Space Telescope European CoordinatingFacility.
| 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.
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Osservazione e dati astrometrici
| Costellazione: | Cigno |
| Ascensione retta: | 20h51m30.70s |
| Declinazione: | +47°42'27.6" |
| Magnitudine apparente: | 7.364 |
| Distanza: | 143.266 parsec |
| Moto proprio RA: | 0.6 |
| Moto proprio Dec: | 24.4 |
| B-T magnitude: | 8.786 |
| V-T magnitude: | 7.482 |
Cataloghi e designazioni:
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