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Публикации по объекту
Observational results for northern and southern (candidate) gamma Doradus stars .
We report on observational results obtained for 78 objects originallyclassified as bona-fide or candidate gamma Doradus stars. For thesouthern objects, we gathered echelle spectra with the CORALIEspectrograph attached to the Euler telescope in 1998-2003 and/orJohnson-Cousins B,V,I_c observations with the MODULAR photometerattached to the 0.5-m SAAO telescope in 1999-2000. For the northernobjects, we obtained Geneva U,B,B_1,B_2,V,V_1,G observations with the P7photometer attached to the 1.2-m Mercator telescope in 2001-2004. Atleast 15 of our objects are binaries, of which 7 are new. For 6binaries, we determined the orbit for the first time. At least 17objects show profile variations and at least 12 objects aremultiperiodic photometric variables. Our results allow us to upgrade 11objects to bona-fide gamma Doradus stars and to downgrade 8 objects toconstant up to the current detection limits. Mode identification isstill ongoing, but so far, only ℓ = 1 and 2 modes have beenidentified.
| A spectroscopic study of southern (candidate) γ Doradus stars. I. Time series analysis
We present the results of a spectroscopic study of 37 southern(candidate) γ Doradus stars based on échelle spectra. Theobserved spectra were cross-correlated with the standard templatespectrum of an F0-type star for easier detection of binary and intrinsicvariations. We identified 15 objects as spectroscopic binaries,including 7 new ones, while another 3 objects are binary suspects. Atleast 12 objects show composite spectra. We could determine the orbitalparameters for 9 binaries, of which 4 turned out to be ellipsoidalvariables. For 6 binaries, we estimated the expected time-base of theorbital variations. Clear profile variations were observed for 17objects, pointing towards stellar pulsation. For 8 of them, we haveevidence that the main spectroscopic and photometric periods coincide.Our results, in combination with prior knowledge from the literature,lead to the classification of 10 objects as new bona fide γDoradus stars, 1 object as a new bona fide δ Scuti star, and 8objects as constant stars. Finally, we determined the projectedrotational velocity by two independent methods. The resulting v sin ivalues range from 3 to 135 {km s-1}. For the bona fideγ Doradus stars, the majority has v sin i below 60 {kms-1}.
| The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of 14 000 F and G dwarfs
We present and discuss new determinations of metallicity, rotation, age,kinematics, and Galactic orbits for a complete, magnitude-limited, andkinematically unbiased sample of 16 682 nearby F and G dwarf stars. Our63 000 new, accurate radial-velocity observations for nearly 13 500stars allow identification of most of the binary stars in the sampleand, together with published uvbyβ photometry, Hipparcosparallaxes, Tycho-2 proper motions, and a few earlier radial velocities,complete the kinematic information for 14 139 stars. These high-qualityvelocity data are supplemented by effective temperatures andmetallicities newly derived from recent and/or revised calibrations. Theremaining stars either lack Hipparcos data or have fast rotation. Amajor effort has been devoted to the determination of new isochrone agesfor all stars for which this is possible. Particular attention has beengiven to a realistic treatment of statistical biases and errorestimates, as standard techniques tend to underestimate these effectsand introduce spurious features in the age distributions. Our ages agreewell with those by Edvardsson et al. (\cite{edv93}), despite severalastrophysical and computational improvements since then. We demonstrate,however, how strong observational and theoretical biases cause thedistribution of the observed ages to be very different from that of thetrue age distribution of the sample. Among the many basic relations ofthe Galactic disk that can be reinvestigated from the data presentedhere, we revisit the metallicity distribution of the G dwarfs and theage-metallicity, age-velocity, and metallicity-velocity relations of theSolar neighbourhood. Our first results confirm the lack of metal-poor Gdwarfs relative to closed-box model predictions (the ``G dwarfproblem''), the existence of radial metallicity gradients in the disk,the small change in mean metallicity of the thin disk since itsformation and the substantial scatter in metallicity at all ages, andthe continuing kinematic heating of the thin disk with an efficiencyconsistent with that expected for a combination of spiral arms and giantmolecular clouds. Distinct features in the distribution of the Vcomponent of the space motion are extended in age and metallicity,corresponding to the effects of stochastic spiral waves rather thanclassical moving groups, and may complicate the identification ofthick-disk stars from kinematic criteria. More advanced analyses of thisrich material will require careful simulations of the selection criteriafor the sample and the distribution of observational errors.Based on observations made with the Danish 1.5-m telescope at ESO, LaSilla, Chile, and with the Swiss 1-m telescope at Observatoire deHaute-Provence, France.Complete Tables 1 and 2 are 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/418/989
| Late-type members of young stellar kinematic groups - I. Single stars
This is the first paper of a series aimed at studying the properties oflate-type members of young stellar kinematic groups. We concentrate ourstudy on classical young moving groups such as the Local Association(Pleiades moving group, 20-150Myr), IC 2391 supercluster (35Myr), UrsaMajor group (Sirius supercluster, 300Myr), and Hyades supercluster(600Myr), as well as on recently identified groups such as the Castormoving group (200Myr). In this paper we compile a preliminary list ofsingle late-type possible members of some of these young stellarkinematic groups. Stars are selected from previously established membersof stellar kinematic groups based on photometric and kinematicproperties as well as from candidates based on other criteria such astheir level of chromospheric activity, rotation rate and lithiumabundance. Precise measurements of proper motions and parallaxes takenfrom the Hipparcos Catalogue, as well as from the Tycho-2 Catalogue, andpublished radial velocity measurements are used to calculate theGalactic space motions (U, V, W) and to apply Eggen's kinematic criteriain order to determine the membership of the selected stars to thedifferent groups. Additional criteria using age-dating methods forlate-type stars will be applied in forthcoming papers of this series. Afurther study of the list of stars compiled here could lead to a betterunderstanding of the chromospheric activity and their age evolution, aswell as of the star formation history in the solar neighbourhood. Inaddition, these stars are also potential search targets for directimaging detection of substellar companions.
| Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics
The Catalogue, available at the Centre de Données Stellaires deStrasbourg, consists of 13 573 records concerning the results obtainedfrom different methods for 7778 stars, reported in the literature. Thefollowing data are listed for each star: identifications, apparentmagnitude, spectral type, apparent diameter in arcsec, absolute radiusin solar units, method of determination, reference, remarks. Commentsand statistics obtained from CADARS are given. The Catalogue isavailable 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/qcar?J/A+A/367/521
| FAUST observations in the Fourth Galactic Quadrant*
We analyse UV observations with FAUST of four sky fields in the generaldirection of the Fourth Galactic Quadrant, in which we detect 777 UVsources. This is ~50 per cent more than detected originally by Bowyer etal. We discuss the source detection process and the identification of UVsources with optical counterparts. For the first time in this project weuse ground-based objective-prism information for two of the fields, toselect the best-matching optical objects with which to identify the UVsources. Using this, and correlations with existing catalogues, wepresent reliable identifications for ~75 per cent of the sources. Mostof the remaining sources have assigned optical counterparts but, lackingadditional information, we offer only plausible identifications. Wediscuss the types of objects found, and compare the observed populationwith predictions of our UV Galaxy model.
| A search for new gamma Doradus stars in the Geneva photometric database
We present a study of selected potential gamma Doradus stars observed inthe Geneva photometric system. Eleven stars were monitored at leastduring the last year of functioning of the 70 cm Swiss telescope at LaSilla, leading to about one thousand photometric measurements andpermitting a detailed analysis of these stars. After the analysis, fivestars are thought to be constant stars. We report three new gamma Dorstars. A spectroscopic campaign has been started at La Silla with thenew 1m20 Swiss telescope, equipped with the spectrograph CORALIE, ofwhich we show the results for the selected stars.
| Two-colour photometry for 9473 components of close Hipparcos double and multiple stars
Using observations obtained with the Tycho instrument of the ESAHipparcos satellite, a two-colour photometry is produced for componentsof more than 7 000 Hipparcos double and multiple stars with angularseparations 0.1 to 2.5 arcsec. We publish 9473 components of 5173systems with separations above 0.3 arcsec. The majority of them did nothave Tycho photometry in the Hipparcos catalogue. The magnitudes arederived in the Tycho B_T and V_T passbands, similar to the Johnsonpassbands. Photometrically resolved components of the binaries withstatistically significant trigonometric parallaxes can be put on an HRdiagram, the majority of them for the first time. Based on observationsmade with the ESA Hipparcos satellite.
| Candidate Main-Sequence Stars with Debris Disks: A New Sample of Vega-like Sources
Vega-like sources are main-sequence stars that exhibit IR fluxes inexcess of expectations for stellar photospheres, most likely due toreradiation of stellar emission intercepted by orbiting dust grains. Wehave identified a large sample of main-sequence stars with possibleexcess IR radiation by cross-correlating the Michigan Catalog ofTwo-dimensional Spectral Types for the HD Stars with the IRAS FaintSource Survey Catalog. Some 60 of these Vega-like sources were not foundduring previous surveys of the IRAS database, the majority of whichemployed the lower sensitivity Point Source Catalog. Here, we providedetails of our search strategy, together with a preliminary examinationof the full sample of Vega-like sources.
| Line profile variations in gamma Doradus.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996MNRAS.281.1315B&db_key=AST
| The Stellar Content of Star Stream I
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996AJ....111.1615E&db_key=AST
| A catalog of far-ultraviolet point sources detected with the fast FAUST Telescope on ATLAS-1
We list the photometric measurements of point sources made by the FarUltraviolet Space Telescope (FAUST) when it flew on the ATLAS-1 spaceshuttle mission. The list contains 4698 Galactic and extragalacticobjects detected in 22 wide-field images of the sky. At the locationssurveyed, this catalog reaches a limiting magnitude approximately afactor of 10 fainter than the previous UV all-sky survey, TDl. Thecatalog limit is approximately 1 x 10-14 ergs A sq cm/s,although it is not complete to this level. We list for each object theposition, FUV flux, the error in flux, and where possible anidentification from catalogs of nearby stars and galaxies. Thesecatalogs include the Michigan HD (MHD) and HD, SAO, the HIPPARCOS InputCatalog, the Position and Proper Motion Catalog, the TD1 Catalog, theMcCook and Sion Catalog of white dwarfs, and the RC3 Catalog ofGalaxies. We identify 2239 FAUST sources with objects in the stellarcatalogs and 172 with galaxies in the RC3 catalog. We estimate thenumber of sources with incorrect identifications to be less than 2%.
| Ca II H and K Filter Photometry on the UVBY System. II. The Catalog of Observations
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....109.2828T&db_key=AST
| 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.
| The position corrections of 1400 stars observed with PA II in San Juan.
Not Available
| Photometry and Line Profile Variations of the Peculiar Variable Gamma-Doradus
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1994MNRAS.267..103B&db_key=AST
| Second astrolabe catalogue of Santiago.
Positions for 350 FK5 and 164 FK5 Extension stars as determined with theDanjon astrolabe of Santiago and differences astrolabe-catalogue aregiven for Equinox J2000.0 and for the mean observation epoch of eachstar. The average mean error in alpha is +/-0.005s and +/-0.07" indelta. The mean epoch of observation of the catalogue is J1979.96.
| The Hyades supercluster in the FK5
The members of the Hyades supercluster brighter than about M(V) = + 4mag and contained in the FK5, or having nearly FK5 quality propermotions, show a convergent point of (A,D) = (6h, + 6.5 deg). The Hyadescluster stars in the FK5 have a mean distance of 46.7 pc. Thesupercluster, as well as the Hyades and Praesepe cluster, populationsrepresent at least three age groups. Standard models indicate ages of 3to 4, 6, and 8 x 10 exp 8 yr, whereas model ages with convectiveovershoot are nearly twice this. Most of the Am and USPC stars in thesupercluster are of the same age. The Ap stars mark the onset of shellhydrogen burning. The photometry of the red giants confirms the agespread and indicates a weakening of CN strength with age. Attention iscalled to the need for further study of NGC 2423 as an effectiveprolusion to understanding the evolution of the supercluster.
| Fifth fundamental catalogue. Part 2: The FK5 extension - new fundamental stars
The mean positions and proper motions for 3117 new fundamental starsessentially in the magnitude range about 4.5 to 9.5 are given in thisFK5 extension. Mean apparent visual magnitude is 7.2 and is on average2.5 magnitudes fainter then the basic FK5 which has a mean magnitude of4.7. (The basic FK5 gives the mean positions and proper motions for theclassical 1535 fundamental stars). The following are discussed: theobservational material, reduction of observations, star selection, andthe system for the FK5 extension. An explanation and description of thecatalog are given. The catalog of 3117 fundamental stars for the equinoxand epoch J2000.0 and B1950.0 is presented. The parallaxes and radialvelocities for 22 extension stars with large forecasting effects aregiven. Catalogs used in the compilation of the FK5 fundamental catalogare listed.
| Photometric variations in AP stars observable at La Silla in November and December
Photometric observations of 13 Ap stars made at the European SouthernObservatory at La Silla during November 1977 and December 1978 arereported. Observations were made in the uvby with the four-channelphotometer at the 40-cm telescope in November, and with the one-channelphotometer at the 50-cm telescope in December. Light variations withperiods from 0.724 to 4.64 days are obtained for 11 of the stars,including the Hg-Mn star HR 2202, which was believed not to vary.Extremely small variations are observed in Upsilon 4 Eri, with apossible period of 0.51 days, although the two Mn components are likelyto vary independently. HR 1800 was not observed to vary over two-weekobservation period. The stars 20 Eri, HR 1194, Alpha Dor, 11 Ori and HD36916 are also noted to exhibit relatively large variations for Apstars.
| The chemical evolution of the solar neighborhood. I - A bias-free reduction technique and data sample
The possible ways of measuring the age-metallicity relation for thegalactic disk in the neighborhood of the sun are discussed. It is shownthat the use of a field star sample chosen on the basis of effectivetemperature introduces a bias which results in a monotonic increase inthe metal abundance of the disk with time. However, if theage-metallicity relation for the disk can be shown to satisfy certaincriteria, the bias introduced in such a sample can be neglected: thegalactic disk apparently satisfies the criteria. It is concluded that asample analyzed through the use of uvby and H(beta) photometry inconjunction with a self-consistent set of theoretical isochronesprovides the least biased, most accurate estimate of the age-metallicityrelation for the disk.
| Study of the F-type 1 MK spectral types.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975AJ.....80..637M&db_key=AST
| Luminosity and velocity distribution of high-luminosity red stars. III. Old-disk-population giants
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973PASP...85..542E&db_key=AST
| Classification of Some Bright F-Type Stars with Unusual Spectra
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973PASP...85..328M&db_key=AST
| Variability of A and F main sequence stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971A&A....12..223J&db_key=AST
| Spectral types and luminosities of B, A and F southern stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1957MNRAS.117..449D&db_key=AST
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Группы:
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Наблюдательные данные и астрометрия
| Созвездие: | Золотая Рыба |
| Прямое восхождение: | 04h18m40.00s |
| Склонение: | -52°51'36.0" |
| Видимая звёздная величина: | 6.09 |
| Расстояние: | 74.129 парсек |
| Собственное движение RA: | 47.1 |
| Собственное движение Dec: | 74.2 |
| B-T magnitude: | 6.672 |
| V-T magnitude: | 6.159 |
Каталоги и обозначения:
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INHABITED SKY
