Contents
Images
Upload your image
DSS Images Other Images
Related articles
Host Dynamics and Origin of Palomar-Green QSOs
We present host galaxy velocity dispersions of 12 local (mainlyPalomar-Green) QSOs measured directly from the stellar CO absorptionfeatures in the H band. The mean bulge dispersion of the QSOs in oursample is 186 km s-1 with a standard deviation of 24 kms-1. The measurement of the stellar dispersion in QSOsenables us to place them on observational diagrams such as the localblack hole mass-bulge velocity dispersion relation and the fundamentalplane of early-type galaxies. Concerning the former relation, these QSOshave higher black hole masses than most Seyfert 1 AGNs with similarvelocity dispersions. On the fundamental plane, PG QSOs are locatedbetween the regions occupied by moderate-mass and giant ellipticals. TheQSO bulge and black hole masses, computed from the stellar velocitydispersions, are of order 1011 and 108Msolar, respectively. The Eddington efficiency of their blackholes is on average 0.25, assuming that all of the bolometric luminosityoriginates from the active nucleus. Our data are consistent with otherlines of evidence that Palomar-Green QSOs are related to galaxy mergerswith gas-rich components and that they are formed in a manner similar tothe most massive ultraluminous infrared galaxies, regardless of theirfar-infrared emission. However, PG QSOs seem to have smaller hostdispersions and different formation mechanisms than QSOs withsupermassive black holes of 5×108-109Msolar that accrete at low rates and reside in massivespheroids.Based on observations at the European Southern Observatory, Chile(171.B-0442).
| 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}
| New periodic variables from the Hipparcos epoch photometry
Two selection statistics are used to extract new candidate periodicvariables from the epoch photometry of the Hipparcos catalogue. Theprimary selection criterion is a signal-to-noise ratio. The dependenceof this statistic on the number of observations is calibrated usingabout 30000 randomly permuted Hipparcos data sets. A significance levelof 0.1 per cent is used to extract a first batch of candidate variables.The second criterion requires that the optimal frequency be unaffectedif the data are de-trended by low-order polynomials. We find 2675 newcandidate periodic variables, of which the majority (2082) are from theHipparcos`unsolved' variables. Potential problems with theinterpretation of the data (e.g. aliasing) are discussed.
| Ultraluminous Infrared Mergers: Elliptical Galaxies in Formation?
We report high-quality near-IR spectroscopy of 12 ultraluminous infraredgalaxy mergers (ULIRGs). Our new VLT and Keck data provide ~0.5"resolution, stellar and gas kinematics of these galaxies, most of whichare compact systems in the last merger stages. We confirm that ULIRGmergers are ``ellipticals in formation.'' Random motions dominate theirstellar dynamics, but significant rotation is common. Gasdynamics andstellar dynamics are decoupled in most systems. ULIRGs fall on or nearthe fundamental plane of hot stellar systems, and especially on its lessevolution-sensitive, reff-σ projection. The ULIRGvelocity dispersion distribution, their location in the fundamentalplane, and their distribution of vrotsini/σ closelyresemble those of intermediate-mass (~L*), ellipticalgalaxies with moderate rotation. As a group ULIRGs do not resemble giantellipticals with large cores and little rotation. Our results are ingood agreement with other recent studies indicating that diskyellipticals with compact cores or cusps can form through dissipativemergers of gas-rich disk galaxies while giant ellipticals with largecores have a different formation history. Based on observations at theEuropean Southern Observatory, Chile (ESO 65.N-0266, 65.N-0289), and onobservations at the W. M. Keck Observatory, which is operated as ascientific partnership among the California Institute of Technology, TheUniversity of California, and the National Aeronautics and SpaceAdministration. The Keck Observatory was made possible by the generalfinancial support by the W. M. Keck Foundation.
| 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.
| Groups of stars with common motion in the Galaxy - Groups of red supergiants of the luminosity classes I and II
Not Available
| Mass-losing M supergiants in the solar neighborhood
A list of the 21 mass-losing red supergiants (20 M type, one G type; Lgreater than 100,000 solar luminosities) within 2.5 kpc of the sun iscompiled. These supergiants are highly evolved descendants ofmain-sequence stars with initial masses larger than 20 solar masses. Thesurface density is between about 1 and 2/sq kpc. As found previously,these stars are much less concentrated toward the Galactic center thanW-R stars, which are also highly evolved massive stars. Although withconsiderable uncertainty, it is estimated that the mass return by the Msupergiants is somewhere between 0.00001 and 0.00003 solar mass/sq kpcyr. In the hemisphere facing the Galactic center there is much less massloss from M supergiants than from W-R stars, but, in the anticenterdirection, the M supergiants return more mass than do the W-R stars. Theduration of the M supergiant phase appears to be between 200,000 and400,000 yr. During this phase, a star of initially at least 20 solarmasses returns perhaps 3-10 solar masses into the interstellar medium.
| E. W. Fick Observatory stellar radial velocity measurements. I - 1976-1984
Stellar radial velocity observations made with the large vacuumhigh-dispersion photoelectric radial velocity spectrometer at FickObservatory are reported. This includes nearly 2000 late-type starsobserved during 585 nights. Gradual modifications to this instrumentover its first eight years of operation have reduced the observationalerror for high-quality dip observations to + or - 0.8 km/s.
| Etude pour chaque champ de l'absorption et de la repartition des vitesses radiales EN fonction de la distance.
Not Available
| Mesures de vitesses radiales au spectrographe C de l'Observatoire de Haute Provence
Not Available
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
| Constellation: | はくちょう座 |
| Right ascension: | 21h02m35.11s |
| Declination: | +48°01'50.5" |
| Apparent magnitude: | 6.879 |
| Distance: | 327.869 parsecs |
| Proper motion RA: | 9.5 |
| Proper motion Dec: | 6.6 |
| B-T magnitude: | 9.115 |
| V-T magnitude: | 7.064 |
Catalogs and designations:
|
INHABITED SKY
