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Pulkovo compilation of radial velocities for 35495 stars in a common system.
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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}
| Optical morphology and kinematics of the inner regions of NGC 4736.
The inner regions (R~1-2') of the nearby Sab type galaxy NGC 4736 (M 94)were observed using three different optical techniques: long-slitspectroscopy, CCD surface photometry and imaging spectroscopy,concentrating on the inner ring (R =~50"), which was previously found tobe kinematically and/or morphologically anomalous. A systemic velocityof 311+/-2km/s and a stellar central velocity dispersion of ca.120+/-15km/s were found from the spectra. Curves of radial velocity(v_rad_) versus radius for the stars on one hand and ionised gas on theother show a difference of 40km/s in amplitude. This is satisfactorilyexplained by a relatively simple model for the asymmetric drift of thestars, which assumes a constant ratio of vertical to radial velocitydispersion. In the v_rad_(R) curves for the stars (absorption lines), aca. 50km/s dip is observed to the East to Southeast of the nucleus. Thisfeature is not seen in the emission line results. Comparison of themeasured radial velocities with a model for galaxian rotation indicatesa kinematic major axis position angle for the stars of 105 to 110deg,which is some 10deg lower than previously found. A B-R map shows spiralstructure inside the inner ring, probably defined by dust, ascorroborated by a B-K' map made with a K' image from a third party.Subtraction of the rotationally symmetric component of the inner 50"from the R frame clearly shows an elongated structure in the inner ca.12" of radius, found earlier by others in a K image. The Hαdistribution and velocity field presented here agree well with previousresults. A residual velocity map indicates anomalous velocities in thegas of order 10-15km/s in the South-Eastern ring quadrant, as was alsofound before. Axisymmetric rotation model fits to the Hα velocityfield yield a systemic velocity of 317+/-4km/s, kinematic major axisposition angle within 3deg around 116deg and an essentially constantrotation velocity of 217km/s when fixing the inclination at 31deg forthe inner ring (R in [35", 55"]). When left a free fit parameter, thekinematic inclination of the ionised gas in the inner ring is notwell-determined by these fits. Major axis position angles, bothmorphologic and kinematic, of different galaxian constituents (stars,ionised gas, neutral gas) are compared in detail. Morphologic values arefound to be larger than kinematic ones for any one constituent, by some10deg for stars and for HII gas. Also, both the morphologic andkinematic values from the stellar continuum are lower than those foundfrom Hα and HI, again by some 10deg.
| The Perkins catalog of revised MK types for the cooler stars
A catalog is presented listing the spectral types of the G, K, M, and Sstars that have been classified at the Perkins Observatory in therevised MK system. Extensive comparisons have been made to ensureconsistency between the MK spectral types of stars in the Northern andSouthern Hemispheres. Different classification spectrograms have beengradually improved in spite of some inherent limitations. In thecatalog, the full subclasses used are the following: G0, G5, G8, K0, K1,K2, K3, K4, K5, M0, M1, M2, M3, M4, M5, M6, M7, and M8. Theirregularities are the price paid for keeping the general scheme of theoriginal Henry Draper classification.
| JHK photometry of population I CN-rich field giants
IR JHK photometry has been obtained for a sample of CN-rich field redgiants. It is found that these giants segregate according to metallicityor CN band strength in the (J-H), (H-K) two-color diagram. A delta (H-K)color-excess index is presented, which correlates with the strength ofthe 4215 wavelength CN band as measured by the delta C(m) index of theDDO photometric system (McClure, 1970). The sensitivity of delta (H-K)as a metal abundance indicator is shown to be relatively small. It issuggested that the CN-rich field giants have colors comparable to manyof the metal-rich giants in the Galactic bulge studied by Whitford andRich (1983), although a few of the bulge giants appear to have higherabundances.
| A comparison between Washington and DDO photometry of field red giants
Washington CMT1T2 photometry of a sample of field red giants is comparedwith DDO colors obtained by McClure (1970) and Janes (1975) to determinethe relative sensitivities of the metallicity indices of the twosystems. Washington line-blanketing indices delta(M-T1) and delta(C-M)were derived, and found to correlate very well with each other, inaddition to correlating quite well with the DDO metallicity index.Furthermore, any N/A or C/A abundance variations which may exist amongthe present sample of old disk giants do not appear to significantlyeffect the delta(C-M) index. The study indicates that delta(C-M) shouldprovide a useful photometric metal abundance indicator, and is capableof providing estimates accurate to about + or - 0.2 dex over the Fe/Habundance range of +0.4 to -0.8.
| A spectrophotometric survey of stars along the Milky Way. IV
In the present paper a catalogue of spectrophotometric quantities,spectral types, monochromatic magnitudes and colour equivalents is givenfor all stars brighter than the magnitude m4400 = 10.5 in aregion of the Milky Way in Perseus. No absorption is found for starscloser than about r = 100 pc. The absorbing clouds are situated atdistances closer than 1 kpc and at about 2.5 kpc in the local arm andthe Perseus arm, respectively. The space between the two arms is freefrom absorption. It is also concluded that the Perseus arm continuesbeyond l = 140 deg, containing not only hydrogen gas but also dust to atleast l = 150 deg), while the content of OB stars decreases abruptly atl = 140 deg.
| Scanner Abundance Studies.IV. Observations of Some Strong-Cn and Miscellaneous Evolved Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972ApJ...173..619T&db_key=AST
| Stars with Strong Cyanogen Absorption
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971ApJ...163...75S&db_key=AST
| A photoelectric investigation of strong cyanogen stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75...41M&db_key=AST
| Stellar Spectra in Milky way Regions.VI. a Region in Camelopardalis.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1956ApJS....2..298M&db_key=AST
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| קבוצת-כוכבים: | ג'ירף |
| התרוממות ימנית: | 04h02m39.79s |
| סירוב: | +56°23'04.8" |
| גודל גלוי: | 8.294 |
| מרחק: | 255.754 פארסק |
| תנועה נכונה: | 39.7 |
| תנועה נכונה: | -46.3 |
| B-T magnitude: | 9.719 |
| V-T magnitude: | 8.412 |
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