Tartalom
Képek
Kép feltöltése
DSS Images Other Images
Kapcsolódó cikkek
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}
| The Indo-US Library of Coudé Feed Stellar Spectra
We have obtained spectra for 1273 stars using the 0.9 m coudéfeed telescope at Kitt Peak National Observatory. This telescope feedsthe coudé spectrograph of the 2.1 m telescope. The spectra havebeen obtained with the no. 5 camera of the coudé spectrograph anda Loral 3K×1K CCD. Two gratings have been used to provide spectralcoverage from 3460 to 9464 Å, at a resolution of ~1 Å FWHMand at an original dispersion of 0.44 Å pixel-1. For885 stars we have complete spectra over the entire 3460 to 9464 Åwavelength region (neglecting small gaps of less than 50 Å), andpartial spectral coverage for the remaining stars. The 1273 stars havebeen selected to provide broad coverage of the atmospheric parametersTeff, logg, and [Fe/H], as well as spectral type. The goal ofthe project is to provide a comprehensive library of stellar spectra foruse in the automated classification of stellar and galaxy spectra and ingalaxy population synthesis. In this paper we discuss thecharacteristics of the spectral library, viz., details of theobservations, data reduction procedures, and selection of stars. We alsopresent a few illustrations of the quality and information available inthe spectra. The first version of the complete spectral library is nowpublicly available from the National Optical Astronomy Observatory(NOAO) via ftp and http.
| The Pul-3 catalogue of 58483 stars in the Tycho-2 system
A catalogue of positions and proper motions of 58483 stars (Pul-3) hasbeen constructed at the Pulkovo observatory. The Pul-3 is based on theresults of measurements of photographic plates with galaxies (Deutsch'splan). All plates were taken using the Pulkovo Normal Astrograph (thefirst epoch is in the 1950s and the second epoch is in the 1970s).The Pul-3 catalogue contains stars of mainly 12 to 16.5 mag in 146fields with galaxies in the declination zone from -5o to+85o. The Tycho-2 has been used as a reference catalogue.The mean epoch of the Pul-3 is 1963.25. The internal positional accuracyof the Pul-3 catalogue at the mean epoch of observations is ±80mas. The accuracy of the proper motions is mostly within ±3mas/yr to ±12 mas/yr. Comparisons of the Pul-3 with Tycho-2 andARIHIP have been done at the mean epoch of the Pul-3. The Pul-3 externalpositional accuracy relative to Tycho-2 is ±150 mas.The catalogue is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/357
| Observations of Galaxies with the Midcourse Space Experiment
We have imaged eight nearby spiral galaxies with the SPIRIT III infraredtelescope on the Midcourse Space Experiment (MSX) satellite in themid-infrared at 18" resolution at 8.3, 12.1, 14.7, and 21.3 μm. Eachof the eight shows interesting structure not previously detected witholder, lower resolution infrared data sets, such as a resolved nucleusor spiral structure. The MSX data are compared with existing data setsat ultraviolet, optical, and infrared wavelengths, including recentobservations from the Infrared Space Observatory. The infraredstructures in M83 and NGC 5055 show a striking similarity to theultraviolet emission but are less similar to the optical emission.Several point sources with no identified counterparts at otherwavelengths are found near M31, NGC 4945, M83, and M101. Over 200previously known objects are also detected at 8 μm.
| The X-ray view of M 33 after ROSAT
We present a catalogue of 184 X-ray sources within 50' of the nucleus ofthe local group spiral galaxy M 33. The catalogue is derived from ananalysis of the complete set of ROSAT archival data pointed in thedirection of M 33 and contains X-ray position, existence likelihood,count rates and PSPC spectral hardness ratios. To identify the sourcesthe catalog was correlated with previous X-ray catalogues, optical andradio catalogues. In addition sources were classified according to theirX-ray properties. We find seven candidates for supersoft X-ray sources,of which two may be associated with known planetary nebulae in M 33. Themajority of X-ray detected supernova remnants is also detected at radiofrequencies and seen in optical lines. The low overall X-ray detectionrate of optically selected SNRs can probably be attributed to theirexpansion into interstellar matter of low density. Table~2 is onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/373/438
| GPM1 - a catalog of absolute proper motions of stars with respect to galaxies
The description of the first version of the General Compiled Catalogueof Absolute Proper Motions (GPM1) for a sample of HIPPARCOS stars,derived with respect to galaxies within the plan called Catalogue ofFaint Stars (KSZ, Deutch 1952), is presented. The principal aim of theGPM1 construction was to provide absolute proper motions of stars todetermine the rotation of the HIPPARCOS system. The GPM1 cataloguecontains 977 HIPPARCOS Input Catalogue stars with V magnitudes $5^m -11^m in 180 fields north of -25 degrees of declination. The accuracy ofthe proper motions is 8 mas/yr (milliarcseconds per year). Comparison ofproper motions of GPM1 with those of the PPM and ACRS was performed andanalyzed with respect to systematic errors caused by spurious rotationof the FK5 system. The standard errors show that the rotation may bedetermined with an accuracy better than 1 mas/yr. Catalog is onlyavailable in electronic form at the CDS via anonymous ftpcdsarc.u-strasbg.fr or ftp 130.79.128.5.
| GPM - compiled catalogue of absolute proper motions of stars in selected areas of sky with galaxies.
Not Available
| A Deep X-Ray Image of M33
A 50.4 ks ROSAT Position Sensitive Proportional Counter image of thenearby spiral galaxy M33 reveals 37 sources within 15' of the nucleusbrighter than 7 x 10^35^ ergs s^-1^. There are at least 13 additionalsources farther from the nucleus, most of which are likely to beassociated with M33 as well. Most of the bright sources that had beendetected with Einstein in the same region are still visible. The bulk ofthe sources in the galaxy are associated with Population I tracers.Several of the sources are time variable. There are 10 sources in theimage that lie within 20" of optically identified supernova remnants(SNRs) in M33. The spectra of these sources are soft compared with mostother sources of comparable brightness, and therefore it is likely thatmost of these X-ray sources are SNRs. Based on the identification ofsources in M33, it appears likely that ROSAT hardness ratios of thistype can be used to separate SNRs and compact sources in other nearbynormal galaxies as well. The northern and the southern spiral arms ofM33 appear as diffuse features in the X-ray image. There is additionaldiffuse (or unresolved source) emission throughout the inner portions ofM33. The diffuse emission is softer than the faint point sources and theSNRs in the survey, and is well fitted in terms of a bremsstrahlungspectrum with kT ~ 0.4 keV and log N_H_ ~ 20.6.
| 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.
| A detailed study of a very late WN star in M 33.
We present the first quantitative analysis of a M 33 Wolf-Rayet star,the Ofpe/WN9 candidate MCA1-B (Willis et al. 1992). From new higherresolution observations analysed with the Wolf-Rayet standard model, wereclassify MCA1-B as WN9 and find its stellar parameters (T_*_=29kK,T_eff_=19kK, log L/Lsun_=5.8, log˙(M)/Msun_/yr=-4.0, vinfinity_=420km/s) to bevery similar to the LMC WN9 stars (Crowther et al. 1995a), and R84 inparticular. Chemical abundances (H/He=2.6, N/He=0.003, C/N<0.1) arealso comparable to R84 indicating a similar evolutionary status(probable dormant LBV) and metallicity (Z~0.008) consistent with itslocation in the outer regions of M 33.
| A critical appraisal of published values of (Fe/H) for K II-IV stars
'Primary' (Fe/H) averages are presented for 373 evolved K stars ofluminosity classes II-IV and (Fe/H) values beween -0.9 and +0.21 dex.The data define a 'consensus' zero point with a precision of + or -0.018 dex and have rms errors per datum which are typically 0.08-0.16dex. The primary data base makes recalibration possible for the large(Fe/H) catalogs of Hansen and Kjaergaard (1971) and Brown et al. (1989).A set of (Fe/H) standard stars and a new DDO calibration are given whichhave rms of 0.07 dex or less for the standard star data. For normal Kgiants, CN-based values of (Fe/H) turn out to be more precise than manyhigh-dispersion results. Some zero-point errors in the latter are alsofound and new examples of continuum-placement problems appear. Thushigh-dispersion results are not invariably superior to photometricmetallicities. A review of high-dispersion and related work onsupermetallicity in K III-IV star is also given.
| The galactic foreground reddening in the direction of the nearby triangulum galaxy M33
Observations of 314 stars with the uvby-beta photometric system are usedto establish the reddening in the direction of the nearby Triangulumgalaxy M33. Color excesses are obtained for 151 A and F type stars in a1 deg radius centered around the galaxy. A color excess of E(b-y) =0.057 mag /E(B-V) = 0.077 mag/ is obtained for a distance modulus m - M= 10. A secondary result of this investigation is the discovery of sixsuspected variable stars, as well as ten observations of V Triangulum, aBeta Lyrae eclipsing variable.
| A Preliminary Photoelectric Sequence in the Galaxy M33 of the Local Group
Abstract image available at:http://adsabs.harvard.edu/abs/1974ApJ...191...63S
| Determination of atmospheric parameters for G and K giants by means of photoelectric indices.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971A&A....15..123H&db_key=AST
| Catalog of Indidual Radial Velocities, 0h-12h, Measured by Astronomers of the Mount Wilson Observatory
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJS...19..387A&db_key=AST
|
Új cikk hozzáadása
Kapcsolódó hivatkozások
- - (nincs kapcsolódó hivatkozás) -
Új link hozzáadása
Besorolás csoportokba:
|
Pozíciós és asztrometriai adatok
| Csillagkép: | Északi Háromszög |
| Rektaszcenzió: | 01h31m46.67s |
| Deklináció: | +30°37'29.2" |
| Vizuális fényesség: | 8.081 |
| Távolság: | 440.529 parszek |
| RA sajátmozgás: | 73.4 |
| Dec sajátmozgás: | -37.6 |
| B-T magnitude: | 9.394 |
| V-T magnitude: | 8.19 |
Katalógusok és elnevezések:
|
