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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
| Measuring the Fundamental Parameters of Hot Hydrogen-Rich White Dwarfs
This review considers the observations of hot, hydrogen-rich white dwarfstars, with particular reference to measurements of temperature, surfacegravity and composition. Spectroscopic data from a variety of wavelengthranges are required for this work and, in particular, the importantcontributions from optical, ultraviolet and extreme ultraviolet studiesare discussed. Using the values of Teff and log g determinedfor an individual white dwarf, estimates of mass and radius might bederived from the theoretical mass-radius relation. The issue of theaccuracy of the theoretical mass-radius calculations and the prospectsfor making empirical tests using observational data are outlined.
| An Archive of IUE Low-Dispersion Spectra of the White Dwarf Stars
We have produced an archive of the ultraviolet low-dispersion spectrafor the full set of white dwarf stars observed with the InternationalUltraviolet Explorer (IUE) satellite over the course of its 18 yrmission. This archive contains the spectra of 322 individual degeneratestars which have been processed to optimize the signal-to-noise for eachstar. In particular, all spectra have been corrected for residualtemporal and thermal effects and placed on the Hubble Space TelescopeFaint Object Spectrograph absolute flux scale using procedures describedby Massa & Fitzpatrick. Wherever possible, multiple observations ofindividual stars have been co-added to further enhance signal-to-noiseand have been combined into a single spectrum including the full 1150 to3150 Å wavelength region observed by IUE. The contents of thisspectral archive are described and the details of data reductionprocedures are provided, along with the url for access to the electronicfiles of the processed spectra.
| Resolving Sirius-like binaries with the Hubble Space Telescope
We present initial results from a Hubble Space Telescope ultravioletimaging survey of stars known to have hot white dwarf companions whichare unresolved from the ground. The hot companions, discovered throughtheir EUV or UV emission, are hidden by the overwhelming brightnesses ofthe primary stars at visible wavelengths. Out of 17 targets observed, wehave resolved eight of them with the Wide Field Planetary Camera 2,using various ultraviolet filters. Most of the implied orbital periodsfor the resolved systems are hundreds to thousands of years, but in atleast three cases (56 Persei, ζ Cygni and RE J1925-566) it shouldbe possible to detect the orbital motions within the next few years, andthey may eventually yield new dynamically determined masses for thewhite dwarf components. The 56 Persei and 14 Aurigae systems are foundto be quadruple and quintuple, respectively, including the known opticalcomponents as well as the newly resolved white dwarf companions. Themild barium star ζ Cygni, known to have an 18-year spectroscopicperiod, is marginally resolved. All of these newly resolved Sirius-typebinaries will be useful in determining gravitational redshifts andmasses of the white dwarf components.
| Research Note Hipparcos photometry: The least variable stars
The data known as the Hipparcos Photometry obtained with the Hipparcossatellite have been investigated to find those stars which are leastvariable. Such stars are excellent candidates to serve as standards forphotometric systems. Their spectral types suggest in which parts of theHR diagrams stars are most constant. In some cases these values stronglyindicate that previous ground based studies claiming photometricvariability are incorrect or that the level of stellar activity haschanged. Table 2 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/367/297
| A Catalog of Spectroscopically Identified White Dwarfs
A catalog of 2249 white dwarfs which have been identifiedspectroscopically is presented complete through 1996 April. Thiscompilation is the fourth edition of the Villanova Catalog ofSpectroscopically Identified White Dwarfs. For each degenerate star, thefollowing data entries with references are provided: (1) a catalogcoordinate designation or WD number, in order of right ascension; (2)the right ascension and declination for epoch 1950.0; (3) the spectraltype based upon the new system; (4) a catalog symbol denoting binarymembership; (5) a list of most names known to exist for a given star;(6) proper motion and position angle; (7) broadband UBV photometry, V,B-V, U-B (8) multichannel spectrophotometry, v(MC), g-r (9)Strömgren narrowband photometry, y, b-y, u-b (10) an absolutevisual magnitude based upon the best available color-magnitudecalibration or trigonometric parallax; (11) the observed radial velocityuncorrected for gravitational redshift or solar motion; and (12) thetrigonometric parallax with mean error when available. Notes for unusualor peculiar stars and a coded Reference Key alphabetized by the firstauthor's last name are presented, as well as an expanded tablecross-referencing all names to the catalog WD number. An introductionand full descriptions of the entries are provided in the text.
| The ROSAT all-sky survey catalogue of optically bright main-sequence stars and subgiant stars
We present X-ray data for all main-sequence and subgiant stars ofspectral types A, F, G, and K and luminosity classes IV and V listed inthe Bright Star Catalogue that have been detected as X-ray sources inthe ROSAT all-sky survey; several stars without luminosity class arealso included. The catalogue contains 980 entries yielding an averagedetection rate of 32 percent. In addition to count rates, sourcedetection parameters, hardness ratios, and X-ray fluxes we also listX-ray luminosities derived from Hipparcos parallaxes. The catalogue isalso available in electronic form via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| The White-Dwarf Companions of 56 Persei and HR 3643
We have obtained low-dispersion IUE spectra of the stars 56 Persei (F4V) and HR 3643 (F7 II), as part of a survey of late-type stars with a1565A flux excess in the TD-1 ultraviolet sky survey. The IUE spectrumof each star reveals the presence of a hot white dwarf companion. We fitthe Ly-alpha profile and ultraviolet continuum using pure hydrogenmodels, but the distance of the primary star is also needed to uniquelyconstrain the white dwarf parameters. We derive Teff = 16,420 +- 420 K,log g= 8.46 +- 0.2 for the white dwarf companion to 56 Per, using thephotometric distance of 30.1 +- 2.8 pc. The implied white dwarf mass is0.90 +- 0.12 solar mass, considerably above the median mass (~0.6 solarmass) of single white dwarfs. The parameters of the white dwarf in HR3643 are not well constrained, mainly due to a large uncertainty in thedistance. By assuming a reasonable range of gravity for the white dwarf(7.3 < log g < 9.0), we derive -1.4 < M_V < 0.6 for the F7II star, adn 28,970 < Teff < 35,990 K for the white dwarf.Prompted by our detection of a white dwarf companion of a luminous Fstar, we have examined the IUE archives to assess the upper limits onpossible white dwarf companions to Cepheids. The detection of aCepheid--white dwarf binary would provide important insights concerningthe most massive progenitors of white dwarfs. Only for the cases ofalpha UMi and Beta Dor are existing IUE spectra of Cepheids sufficientlydeep to rule out the presence of a white dwarf companion. (SECTION:Stars)
| Mesures et decouvertes d'etoiles doubles effectuees a la lunette de 50cm de l'Observatoire de Nice. Measures and discoveries of visual double stars made with the 50cm refractor at the Nice Observatory.
Measures and discoveries of visual double stars made at the Observatoirede la Cote d'Azur at Nice, between 1988 and 1994, with the 50cmrefractor equipped with a filar micrometer and electronic recordingdevice. The programs proposed by J. Dommanget involve the complement ofthe C.C.D.M. (resolving problems of identification of double stars andof coherency in the Index) and the INput CAtalog Hipparcos (resolutionof ambiguities on the binarity and on the position of certain doublestars which have seldom or never been observed again from the epoch ortheir discovery). The author has discovered three new binaries: JCT1,JCT2 and JCT3.
| 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.
| On the (B-V) colors of the bright stars
The possible causes of the dispersion of (B-V) colors of nearby stars inthe Bright Star Catalog are investigated. The distribution of (B-V)colors is presented for the entire range of spectral classes.Explanations for the dispersion in terms of a nonuniform distribution ofinterstellar absorbing material and a variability of metallicity areaddressed. A new statistical model for reddening by interstellar dustclouds is developed. It is concluded that extinction by nonuniforminterstellar matter is an important contribution to the reddening ofnearby stars, and that a part of the dispersion of (B-V) colors of Kand, possibly, M giants may be due to some unidentified variableproperty of those stars.
| Search for systematic effects in photographic measurements of visual binaries
Photographic plates (265) of selected visual double stars obtained bymeans of the 105 cm astrometric reflector of the AstronomicalObservatory of Torino have been taken during 1984. 118 visual doublestars of this series of observations (the 7th) have been measured twiceby two persons using two different measuring machines. In this paper thesingle measures of the polar coordinates for each person and the averagevalues obtained combining the two types of measures are reported. Ananalysis of the systematic errors due to the two systems of measurementand considerations about the type of motion of each binary are given.
| Narrow-band photometry of late-type stars. II
This paper presents extensive narrow-band photometry in the Uppsalasystem supplementing earlier published mesurements so that data now areavailable for all late-type stars brighter than V = 6.05 and a number ofgalactic cluster members. Numerous UBV and BV measurements are alsopublished. The data are used to determine relations for the predictionof UBV intrinsic colors for late-type stars from the narrow-bandmeasurements. The main purpose of the data is to constitute the basisfor the determination of solar-neighborhood space densities of late-typestars, mainly giants of different kinds; these space densities will becombined with narrow-band data for fainter stars in the north Galacticpole region to yield the decrease of space density with distance fromthe galactic plane for many kinds of late-type stars.
| Visual multiples. VIII - 1000 MK types
A total of 1000 new classifications are given for stars brighter than B= 8.0 mag in the Aitken double star catalog. The classificationssupplement 865 classifications obtained in 1981 and 1984. Among thenewly discovered stars are 12 new Ap stars, eight Lambda Bootis stars,one Ba II star, and 60 Am stars. A detailed list of the newclassifications is given.
| Photographic measures of visual binaries
A fourth series of photographic measures of selected visual binaries hasbeen obtained with the astrometric reflector of the AstronomicalObservatory of Torino. This series contains 143 accurate measures of theastrometric parameters rho and theta which are the result of a criticalselection among the observations. Those having deviations from the meanrho larger than 3 sigma = 0.08 arcsec were rejected. The date ofobservation, angular separation, position angle, and number of exposuresper plate are given.
| Photographic measures of double stars. II
Measures are presented for 302 double stars photographed on 657 plateswith the 36-in. Lick refractor in the period between 1945 and 1962. Thedata provided include the observing epochs, the rectangular coordinatesof the secondary components with reference to the respective primaries,the mean errors of a single measurement, the computed mean errors, thedouble-star separations, and the position angles both for the observingepoch and reduced to the equator of 2000. An additional 561 unmeasuredplates of acceptable quality obtained between 1948 and 1960 are listed.
| Spectral classification of the bright F stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976PASP...88...95C&db_key=AST
| Positions moyennes et mouvements propres de 355 etoiles DU GC de la zone de declinaison +33 +36.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976A&AS...26..219M&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
| Mikrometermessungen von Doppelsternen. VI.
Not Available
| Mouvement relatif linéaire d'étoiles doubles
Not Available
| Stars with large proper motions in the Astrographic zone +32° +33° (list IV)
Not Available
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Pozíciós és asztrometriai adatok
| Csillagkép: | Perszeusz |
| Rektaszcenzió: | 04h24m37.40s |
| Deklináció: | +33°57'35.0" |
| Vizuális fényesség: | 5.76 |
| Távolság: | 41.667 parszek |
| RA sajátmozgás: | 45.8 |
| Dec sajátmozgás: | -74.5 |
| B-T magnitude: | 6.255 |
| V-T magnitude: | 5.841 |
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