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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
| Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group
Utilizing Hipparcos parallaxes, original radial velocities and recentliterature values, new Ca II H and K emission measurements,literature-based abundance estimates, and updated photometry (includingrecent resolved measurements of close doubles), we revisit the UrsaMajor moving group membership status of some 220 stars to produce afinal clean list of nearly 60 assured members, based on kinematic andphotometric criteria. Scatter in the velocity dispersions and H-Rdiagram is correlated with trial activity-based membership assignments,indicating the usefulness of criteria based on photometric andchromospheric emission to examine membership. Closer inspection,however, shows that activity is considerably more robust at excludingmembership, failing to do so only for <=15% of objects, perhapsconsiderably less. Our UMa members demonstrate nonzero vertex deviationin the Bottlinger diagram, behavior seen in older and recent studies ofnearby young disk stars and perhaps related to Galactic spiralstructure. Comparison of isochrones and our final UMa group membersindicates an age of 500+/-100 Myr, some 200 Myr older than thecanonically quoted UMa age. Our UMa kinematic/photometric members' meanchromospheric emission levels, rotational velocities, and scattertherein are indistinguishable from values in the Hyades and smaller thanthose evinced by members of the younger Pleiades and M34 clusters,suggesting these characteristics decline rapidly with age over 200-500Myr. None of our UMa members demonstrate inordinately low absolutevalues of chromospheric emission, but several may show residual fluxes afactor of >=2 below a Hyades-defined lower envelope. If one defines aMaunder-like minimum in a relative sense, then the UMa results maysuggest that solar-type stars spend 10% of their entire main-sequencelives in periods of precipitously low activity, which is consistent withestimates from older field stars. As related asides, we note six evolvedstars (among our UMa nonmembers) with distinctive kinematics that liealong a 2 Gyr isochrone and appear to be late-type counterparts to diskF stars defining intermediate-age star streams in previous studies,identify a small number of potentially very young but isolated fieldstars, note that active stars (whether UMa members or not) in our samplelie very close to the solar composition zero-age main sequence, unlikeHipparcos-based positions in the H-R diagram of Pleiades dwarfs, andargue that some extant transformations of activity indices are notadequate for cool dwarfs, for which Ca II infrared triplet emissionseems to be a better proxy than Hα-based values for Ca II H and Kindices.
| Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i
This work is the second part of the set of measurements of v sin i forA-type stars, begun by Royer et al. (\cite{Ror_02a}). Spectra of 249 B8to F2-type stars brighter than V=7 have been collected at Observatoirede Haute-Provence (OHP). Fourier transforms of several line profiles inthe range 4200-4600 Å are used to derive v sin i from thefrequency of the first zero. Statistical analysis of the sampleindicates that measurement error mainly depends on v sin i and thisrelative error of the rotational velocity is found to be about 5% onaverage. The systematic shift with respect to standard values fromSlettebak et al. (\cite{Slk_75}), previously found in the first paper,is here confirmed. Comparisons with data from the literature agree withour findings: v sin i values from Slettebak et al. are underestimatedand the relation between both scales follows a linear law ensuremath vsin inew = 1.03 v sin iold+7.7. Finally, thesedata are combined with those from the previous paper (Royer et al.\cite{Ror_02a}), together with the catalogue of Abt & Morrell(\cite{AbtMol95}). The resulting sample includes some 2150 stars withhomogenized rotational velocities. Based on observations made atObservatoire de Haute Provence (CNRS), France. Tables \ref{results} and\ref{merging} are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/393/897
| The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. II. Basic Parameters of Program Stars and the Role of Microturbulence
Paper I of this series presented precise MK spectral types for 372 lateA-, F-, and early G-type stars with the aim of understanding the natureof luminosity classification on the MK spectral classification systemfor this range of spectral types. In this paper, a multidimensionaldownhill simplex technique is introduced to determine the basicparameters of the program stars from fits of synthetic spectra andfluxes with observed spectra and fluxes from Strömgren uvbyphotometry. This exercise yields useful calibrations of the MK spectralclassification system but, most importantly, gives insight into thephysical nature of luminosity classification on the MK spectralclassification system. In particular, we find that in this range ofspectral types, microturbulence appears to be at least as important asgravity in determining the MK luminosity type.
| The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars
This is the first in a series of two papers that address the problem ofthe physical nature of luminosity classification in the late A-, F-, andearly G-type stars. In this paper, we present precise spectralclassifications of 372 stars on the MK system. For those stars in theset with Strömgren uvbyβ photometry, we derive reddenings andpresent a calibration of MK temperature types in terms of the intrinsicStrömgren (b-y)0 index. We also examine the relationshipbetween the luminosity class and the Strömgren c1 index,which measures the Balmer jump. The second paper will address thederivation of the physical parameters of these stars, and therelationships between these physical parameters and the luminosityclass. Stars classified in this paper include one new λ Bootisstar and 10 of the F- and G-type dwarfs with recently discoveredplanets.
| The long-period companions of multiple stars tend to have moderate eccentricities
We examined the statistics of an angle gamma between the radius vectorof a visual companion of a multiple star and the vector of its apparentrelative motion in the system. Its distribution f(gamma ) is related tothe orbital eccentricity distribution in the investigated sample. Wefound that for the wide physical subsystems of the 174 objects from theMultiple Star Catalogue f(gamma ) is bell-shaped. The Monte-Carlosimulations have shown that our f(gamma ) corresponds to the populationof the moderate-eccentricity orbits and is not compatible with thelinear distribution f(e)=2e which follows from stellar dynamics andseems to hold for wide binaries. This points to the absence of highlyelongated orbits among the outer subsystems of multiple stars. Theconstraint of dynamical stability of triple systems is not sufficient toexplain the ``rounded-off'' outer orbits; instead, we speculate that itcan result from the angular momentum exchange in multiple systems duringtheir early evolution.
| On the delta Scuti variability in the pre-main sequence Herbig Ae star HR 5999
A reanalysis of photometric data for the bright, southern Herbig Ae starHR 5999 obtained by Praderie et al. (\cite{r17}) at ESO in 1985 showsdelta Scuti pulsation with the same period, 4.812 d-1, andsemi-amplitude, 6 mmag, found by Kurtz & Marang (\cite{r10}) in dataobtained from SAAO in 1994. HR 5999 is, therefore, a potential candidateto test Breger & Pamyatnykh's (\cite{r4}) predictions ofevolutionary period changes 10 to 100 times faster in pre-main sequencedelta Scuti stars than in post-main sequence stars. We argue that thelow frequency, low amplitude alpha 2 CVn variability of HR6000 with a period near 2 d, and its long-term variability are nohindrance to using it as a comparison star for study of the delta Scutivariability of HR 5999. With a separation of 44 arcsec between HR 5999and HR 6000, and similar brightnesses for the two stars, we urge the useof small telescopes with CCD photometers to obtain the long-term datanecessary for the study of period change. We point out that this can bedone under less-than-ideal photometric conditions and urban lightingwith CCD photometers on small telescopes which are widely available atsmall observatories, at universities and at the home observatories ofserious amateur astronomers.
| A Second Catalog of Orbiting Astronomical Observatory 2 Filter Photometry: Ultraviolet Photometry of 614 Stars
Ultraviolet photometry from the Wisconsin Experiment Package on theOrbiting Astronomical Observatory 2 (OAO 2) is presented for 614 stars.Previously unpublished magnitudes from 12 filter bandpasses withwavelengths ranging from 1330 to 4250 Å have been placed on thewhite dwarf model atmosphere absolute flux scale. The fluxes wereconverted to magnitudes using V=0 for F(V)=3.46x10^-9 ergs cm^-2 s^-1Å^-1, or m_lambda=-2.5logF_lambda-21.15. This second catalogeffectively doubles the amount of OAO 2 photometry available in theliterature and includes many objects too bright to be observed withmodern space observatories.
| A catalogue of [Fe/H] determinations: 1996 edition
A fifth Edition of the Catalogue of [Fe/H] determinations is presentedherewith. It contains 5946 determinations for 3247 stars, including 751stars in 84 associations, clusters or galaxies. The literature iscomplete up to December 1995. The 700 bibliographical referencescorrespond to [Fe/H] determinations obtained from high resolutionspectroscopic observations and detailed analyses, most of them carriedout with the help of model-atmospheres. The Catalogue is made up ofthree formatted files: File 1: field stars, File 2: stars in galacticassociations and clusters, and stars in SMC, LMC, M33, File 3: numberedlist of bibliographical references The three files are only available inelectronic form at the Centre de Donnees Stellaires in Strasbourg, viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5), or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| 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.
| Oxygen abundances in F-type stars of the Hyades and the Ursa Major group
We have derived the oxygen abundances of 50 F-type main-sequence stars,belonging to the Hyades open cluster, the Ursa Major group, and thefield, using an NLTE analysis of the infrared triplet lines of O I at7771-7775 AA. The stars of the middle F-range have previously been shownto exhibit a marked reduction in lithium abundance compared with bothcooler and hotter objects in the same systems: the 'Li gap', for whichseveral explanations have been proposed. Our results here show asubstantial measure of uniformity in the oxygen abundances over therange in T(eff) between 5800 and 7400 K. The data might indicate a smalldip (less than 0.1 dex) in the oxygen abundance for stars located in theLi gap. Microscopic diffusion seems to be the only known mechanism ableto produce an oxygen dip. If this mechanism were also responsible forthe Li gap, it would have to account for a depletion of up to two ordersof magnitude in lithium and, at the same time, less than 0.1 dex inoxygen. We note, however, that turbulent mixing could modify amicroscopic diffusion pattern in order to yield the observed abundances.
| Stellar kinematic groups. I - The Ursa Major group
The Ursa Major Group (UMaG) is studied as a test case for theauthenticity of Stellar Kinematic Groups, using Coravel radialvelocities, recent compilations of astrometric data, and newspectroscopic observations. Spectroscopic age indicators, particularlyindices of the strength of chromospheric emission, are applied tosolar-type candidate members of UMaG, and it is shown that stars thatmeet the spectroscopic criteria also have kinematics that agree betterwith the space motions of the nucleus of UMaG than does the startingsample as a whole. The primary limitation on the precision of kinematicsis now parallaxes instead of radial velocities. These more restrictivekinematic criteria are then applied to other UMaG candidates and a listsummarizing membership is presented. UMaG is also examined as a cluster,confirming its traditional age of 0.3 Gyr, and a mean Fe/H of -0.08 +/-0.09 for those stars most likely to be bona fide members.
| A catalogue of Fe/H determinations - 1991 edition
A revised version of the catalog of Fe/H determinations published by G.Cayrel et al. (1985) is presented. The catalog contains 3252 Fe/Hdeterminations for 1676 stars. The literature is complete up to December1990. The catalog includes only Fe/H determinations obtained from highresolution spectroscopic observations based on detailed spectroscopicanalyses, most of them carried out with model atmospheres. The catalogcontains a good number of Fe/H determinations for stars from open andglobular clusters and for some supergiants in the Magellanic Clouds.
| Secondary spectrophotometric standards
Energy distribution data on 238 secondary standard stars are presentedin the range 3200-7600 A with 50 A step. These stars are common to theCatalog of the Sternberg State Astronomical Institute and the FessenkovAstrophysical Institute. For these stars, the differences betweenspectral energy distribution data of the two catalogs do not exceed 5percent, while the mean internal accuracy of both catalogs data in thisrange are about 3.5 percent. For 99 stars energy distribution data inthe near infrared (6000-10,800 A) obtained at the Sternberg StateAstronomical Institute are also presented.
| X-ray studies of coeval star samples. III - X-ray emission in the Ursa Major stream
Results are reported from a comprehensive survey of X-ray emission fromstars known or suspected to be members of the UMa cluster and/or stream.Of the 42 UMa member stars surveyed, 18 were detected as X-ray sources,and spectral analysis was performed for 10 stars with sufficient X-raycounts. Consideration is given to relations between X-ray luminosity,color, and kinematics of the sample stars, and the X-ray spectra of theUMa stars are discussed in the context of the general problem of stellarX-ray temperatures. Also confirmed is the lack of X-ray-emitting Adwarfs among UMa members; among stars of later spectra type there is arather large dispersion in X-ray luminosity. This dispersion cannotreadily be explained by contamination with field star interlopers andappears rather to be a property of the UMa X-ray luminosity distributionfunction.
| Stellar integrated fluxes in the wavelength range 380 NM - 900 NM derived from Johnson 13-colour photometry
Petford et al. (1988) have reported measured integrated fluxes for 216stars with a wide spread of spectral type and luminosity, and mentionedthat a cubic-spline integration over the relevant Johnson 13-colormagnitudes, converted to fluxes using Johnson's calibration, is inexcellent agreement with those measurements. In this paper a list of thefluxes derived in this way, corrected for a small dependence on B-V, isgiven for all the 1215 stars in Johnson's 1975 catalog with completeentries.
| Lithium and metallicity in the Ursa Major group
The Li abundances for the UMa group F stars are reported, and the UMaLi-temperature profile is compared with that of the Hyades and the ComaBerenices clusters. The (Fe/H) abundances are determined in order toprovide a spectroscopic calibration of photometric indices and anothercriterion for UMa Group membership. The abundances are compared with themetallicity of other young clusters to study the degree of mixing in theGalactic disk in the solar neighborhood.
| Spectroscopic binaries - 15th complementary catalog
Published observational data on the orbital characteristics of 436spectroscopic binaries, covering the period 1982-1986, are compiled intables. The data sources and the organization of the catalog are brieflydiscussed, and notes are provided for each item.
| An Einstein Observatory X-ray survey of main-sequence stars with shallow convection zones
The results of an X-ray survey of bright late A and early F stars on themain B-V sequence between 0.1 and 0.5 are presented. All the stars wereobserved with the Einstein Observatory for a period of at least 500seconds. The survey results show significantly larger X-ray luminositiesfor the sample binaries than for the single stars. It is suggested thatthe difference is due to the presence of multiple X-ray sources inbinaries. It is shown that the X-ray luminosities for single starsincrease rapidly with increasing color, and that the relation Lx/Lbol isequal to about 10 to the -7th does not hold for A stars. No correlationwas found between X-ray luminosity and projected equatorial rotationvelocity. It is argued on the basis of the observations that X-rayemission in the sample stars originated from coronae. The availableobservational evidence supporting this view is discussed.
| Catalogue of the energy distribution data in spectra of stars in the uniform spectrophotometric system.
Not Available
| Infrared photometry of O stars
The results of a survey of 50 O stars in the J, H, K, L, and M bands aredescribed. The observations are described, and the fitting of reddeningrelations to them is discussed. The zero points in the reddeningrelations are related to the intrinsic colors of the samples of normalstars, and these are compared with theoretical colors. The comparisonreveals anomalies at L and M, which are discussed. The residuals for anindividual star from the reddening relations are a measure of itsinfrared excesses, if indeed it has any. How the excesses can be fittedto a stellar wind model to derive a parameter that involves the rate ofmass loss in the wind, the stellar radius and temperature, and windterminal velocity is considered. The results for a number of individualstars are discussed and compared with other mass loss measurements, andit is concluded that no single model is capable of reconciling the IR,UV, radio, and H-alpha observations for the stars.
| Erratum - Errors or Omissions in Star-Identifications in the General Catalogue of Trigonometric Stellar Parallaxes
Not Available
| The Maximum Times and New Light Elements of kappa Bootis
Not Available
| Refined Data for Parallax Stars
Not Available
| Visual multiples. VII - MK classifications
Classifications are given for 865 components of visual multiples; theyshow no systematic differences from the MK system, and the random errorsare one subclass in type and two-thirds of a luminosity class. It isfound that at least 1% of the F-type IV and V stars are weak-lined, 32%of the A4-F1 IV and V stars are Am, and 5% of the A0-A3 IV and V starsare early-type Am. Attention is called to the large fraction (55%) ofthe A3-A9 III-V stars that are of luminosity classes III or IV, unlikethe percentage (16%) at neighboring types.
| Visual Double Stars for the Amateur
Not Available
| Erratum - Discordances Between SAO and HD Numbers for Bright Stars
Not Available
| Spectral types in the Ursa major stream.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978PASP...90..429L&db_key=AST
| 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.
| Rotational velocities and spectral types for a sample of binary systems.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975A&AS...19...91L&db_key=AST
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