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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
| Speckle Interferometry at the US Naval Observatory. VIII.
The results of 2044 speckle interferometric observations of doublestars, made with the 26 inch (66 cm) refractor of the US NavalObservatory, are presented. Each speckle interferometric observation ofa system represents a combination of over a thousand short-exposureimages. These observations are averaged into 1399 mean positions andrange in separation from 0.16" to 14.97", with a mean separation of2.51". This is the eighth in a series of papers presenting measuresobtained with this system and covers the period 2001 March 18 through2001 December 30.
| Nice Observatory CCD measurements of visual double stars (4th series)
We present 176 measurements of 167 visual double stars, made in 2000 and2001 with the 50 cm refractor of the Nice Observatory and attached CCDcamera, using an algorithm based on the adjustment of a tridimensionalmathematical surface (Table 1). Position angle, angular separation andmagnitude difference are given. 33 new binaries (HDS and TDS) discoveredby Hipparcos were measured. Table 1 is only available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) orvia http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/396/933
| Statistics of spectroscopic sub-systems in visual multiple stars
A large sample of visual multiples of spectral types F5-M has beensurveyed for the presence of spectroscopic sub-systems. Some 4200 radialvelocities of 574 components were measured in 1994-2000 with thecorrelation radial velocity meter. A total of 46 new spectroscopicorbits were computed for this sample. Physical relations are establishedfor most of the visual systems and several optical components areidentified as well. The period distribution of sub-systems has a maximumat periods from 2 to 7 days, likely explained by a combination of tidaldissipation with triple-star dynamics. The fraction of spectroscopicsub-systems among the dwarf components of close visual binaries withknown orbits is similar to that of field dwarfs, from 11% to 18% percomponent. Sub-systems are more frequent among the components of widevisual binaries and among wide tertiary components to the known visualor spectroscopic binaries - 20% and 30%, respectively. In triple systemswith both outer (visual) and inner (spectroscopic) orbits known, we findan anti-correlation between the periods of inner sub-systems and theeccentricities of outer orbits which must be related to dynamicalstability constraints. Tables 1, 2, and 6 are only available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/382/118
| 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.
| CCD measurements of visual double stars made with the 74 cm and 50 cm refractors of the Nice Observatory (2nd series)
We present 619 measurements of 606 visual double stars made by CCDimaging from 1996 to 1999 with the 74 cm and 50 cm refractors of theNice observatory. Angular separation, position angle and magnitudedifference are given. Magnitude differences estimated from CCD imagesare compared with magnitude differences given in the Hipparcos catalog.The residuals in angular separation and position angle are computed forbinaries with known orbit. Table 2 is only available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) orvia http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/378/954
| Research Note Nice Observatory CCD measurements of visual double stars (3rd series)
We present the measurements of 58 visual double stars made in 1999 and2000 with the 50 cm refractor of the Nice Observatory and attached CCDcamera, using an algorithm based on the adjustment of a tridimensionalmathematical surface (Table 1). 2 new binaries discovered by Hipparcoswere measured.
| Speckle Interferometry at the US Naval Observatory. VI.
The results of 1068 speckle interferometric observations of doublestars, made with the 26 inch (0.66 m) refractor of the US NavalObservatory, are presented. These observations are averaged into 841means of 815 binary stars. The systems range in separation from 0.22" to6.01" with a mean separation of 2.21" and have a limiting secondarymagnitude of V=12.5. This is the sixth in a series of papers presentingmeasures obtained with this system, and it covers the period 1999January 1 through 2000 January 9.
| ICCD Speckle Observations of Binary Stars. XXIII. Measurements during 1982-1997 from Six Telescopes, with 14 New Orbits
We present 2017 observations of 1286 binary stars, observed by means ofspeckle interferometry using six telescopes over a 15 year period from1982 April to 1997 June. These measurements constitute the 23dinstallment in CHARA's speckle program at 2 to 4 m class telescopes andinclude the second major collection of measurements from the MountWilson 100 inch (2.5 m) Hooker Telescope. Orbital elements are alsopresented for 14 systems, seven of which have had no previouslypublished orbital analyses.
| 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.
| Speckle Interferometry at the US Naval Observatory. III.
Position angles and separations resulting from 2578 speckleinterferometric observations of 590 binary stars are tabulated. This isthe third in a series of papers presenting measures obtained using the66 cm refractor at the US Naval Observatory in Washington, DC, andcovers the period from 1995 June through 1996 December. Program starsrange in separation from 0.2" to 4.3", with a limiting magnitude ofV=11. Random errors are estimated to be 17.0 mas in separation and0.56d/rho in position angle, where rho is the separation in arcseconds.These are the first results acquired using an improved intensified CCDdetector. The new detector, in concert with an intensity-filteringtechnique applied in software, has permitted a 1 mag increase in dynamicrange, to 3.5 mag, for pairs separated by about 2". The instrumentationand calibration are briefly described, with an emphasis on thecharacteristics of the new detector. The software filter used toincrease the dynamic range is also described.
| Speckle Interferometry at the US Naval Observatory. II.
Position angles and separations resulting from 2406 speckleinterferometric observations of 547 binary stars are tabulated. This isthe second in a series of papers presenting measures obtained using the66 cm refractor at the US Naval Observatory in Washington, DC, with anintensified CCD detector. Program stars range in separation from 0.2" to3.8", with Deltam<=2.5 mag and a limiting magnitude of V=10.0. Theobservation epochs run from 1993 January through 1995 August. Randomerrors are estimated to be 14 mas in separation and 0.52d/rho inposition angle, where rho is the separation in arcseconds. Theinstrumentation and calibration are briefly described. Aspects of thedata analysis related to the avoidance of systematic errors are alsodiscussed.
| Visual binary orbits and masses POST HIPPARCOS
The parallaxes from Hipparcos are an important ingredient to derive moreaccurate masses for known orbital binaries, but in order to exploit theparallaxes fully, the orbital elements have to be known to similarprecision. The present work gives improved orbital elements for some 205systems by combining the Hipparcos astrometry with existing ground-basedobservations. The new solutions avoid the linearity constraints andomissions in the Hipparcos Catalog by using the intermediate TransitData which can be combined with ground-based observations in arbitarilycomplex orbital models. The new orbital elements and parallaxes give newmass-sum values together with realistic total error-estimates. To getindividual masses at least for main-sequence systems, the mass-ratioshave been generally estimated from theoretical isochrones and observedmagnitude-differences. For some 25 short-period systems, however, trueastrometric mass-ratios have been determined through the observedorbital curvature in the 3-year Hipparcos observation interval. Thefinal result is an observed `mass-luminosity relation' which falls closeto theoretical expectation, but with `outliers' due to undetectedmultiplicity or to composition- and age-effects in the nonuniformnear-star sample. Based in part on observations collected with the ESAHipparcos astrometry satellite. Tables~ 1, 3, 4 and 6 are also availablein electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr~(130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| CCD and micrometric observations of visual double stars
Relative positions and separations for 65 visual binaries are given. CCDframes were taken at the 1-m coudetelescope and micrometric observationswere carried out at the 65-cm refractor, both at the Venezuelan NationalObservatory. The visual double stars observed were selected from theRamon Maria Aller Observatory program list. In addition, we alsoobserved several long period double stars with poorly determined orbitalelements.
| 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
| Micrometer measurements of double stars from the Spanish observatories at Calar Alto and Santiago de Compostela.
This paper reports 458 micrometer observations of visual double starsmade with the 152 cm. telescope at Calar Alto Observatory (Almeria,Spain) and with the 35 cm. telescope at Ramon Maria Aller Observatory(Santiago de Compostela, Spain). Tables 1 and 2 only available inelectronic form at CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html
| Speckle Interferometry at the US Naval Observatory. I.
We present speckle interferometer measurements of 467 binary stars takenat the US Naval Observatory in Washington, DC, using the 66 cmrefractor, from 1990 October through 1992 December. The observingprogram is designed to provide high-quality observations of binaries inthe 0."3--3."5 range of separations and as faint as 10.0 mag. More than8000 measurements have been made to date, of which we report the resultsfor 2329. Not only is it our intent to provide accurate data forinteresting binary stars, but also, by careful calibration, to firmlyrelate the "classical" astrometry of binary stars to that being obtainedtoday by speckle and that which will soon be obtained by other moderntechniques such as long-baseline optical interferometry.
| 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
| Stars resembling the Sun
This review is primarily directed to the question whether photometricsolar analogues remain such when subjected to detailed spectroscopicanalyses and interpreted with the help of internal stucture models. Inother words, whether the physical parameters: mass, chemicalcomposition, age (determining effective temperature and luminosity),chromospheric activity, equatorial rotation, lithium abundance, velocityfields etc., we derive from the spectral analysis of a photometric solaranalogue, are really close to those of the Sun. We start from 109photometric solar analogues extracted from different authors. The starsselected had to satisfy three conditions: i) their colour index (B-V)must be contained in the interval: Δ (B-V) = 0.59-0.69, ii) theymust possess a trigonometric parallax, iii) they must have undergone ahigh resolution detailed spectroscopic analysis. First, this reviewpresents photometric and spectrophotometric researches on solaranalogues and recalls the pionneering work on these stars by the lateJohannes Hardorp. After a brief discussion on low and high resolutionspectroscopic researches, a comparison is made between effectivetemperatures as obtained, directly, from detailed spectral analyses andthose obtained, indirectly, from different photometric relations. Aninteresting point in this review is the discussion on the tantalilizingvalue of the (B-V)solar of the Sun, and the presentation of anew reliable value of this index. A short restatement of the kinematicproperties of the sample of solar analogues is also made. And, finally,the observational ( T eff, M bol) diagram,obtained with 99 of the initially presented 109 analogues, is comparedto a theoretical ( T eff, M bol) diagram. Thislatter has been constructed with a grid of internal structure models forwhich, (very important for this investigation), the Sun was used asgauge. In analysing the position, with respect to the Sun, of each starwe hoped to find a certain number of stars tightly neighbouring the Sunin mass, chemical composition and state of evolution. The surprisingresult is that the stars occupy in this HR Diagram a rather extendedregion around the Sun, many of them seem more evolved and older than theSun, and only 4 of the evolved stars seem younger. The age of some starsin the sample is also discussed in terms of chromospheric activity andLi-content. Our conclusion is much the same as that contained inprevious papers we have written on the subject: in spite of a muchlarger number of stars, we have not been able to nominate a single starof the sample for a ``perfect good solar twin''. Another aim inbeginning, 25 years ago, this search for solar analogues, was to haveready a bunch of stars resembling the Sun and analysed spectroscopicallyin detail, in order that, when planets hunters of solar type stars,finally would have found such a specimen, we would have been able toimmediately compare the physical parameters of this star to those of theSun. We have been lucky enough: one of the good solar analogues wepresent herewith, is 51 Pegasi (HD 217014) which, according to the veryrecent observations by Mayor and Queloz (1995), has a planet orbitingaround it. And what is more: two other stars possessing planets: 47Ursae Majoris (HD 95128) and 70 Virginis (HD 117176), have just beendiscovered by Marcy and Butler (187th Meeting of the AAS,January 1996). One of them, 47 Ursae Majoris, is also included in thelist of photometric solar analogues. The other star, 70 Virginis, hasonly been included after the ``Planets News'', because the colour index(B-V) of this star is slightly higher than the prescribted limit of theselection, (B-V = 0.71, instead, 0.69). It would have been a pity toleave the third '' planet star out of the competition.
| CCD observations of visual binary stars.
Not Available
| 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.
| Is this orbit really necessary? III. On the use of Hipparcus double-star measurements for orbit computation.
In this paper the advisability of computing some double star orbits isdiscussed. As a conclusion, it appears that the Hipparcos double starmeasurements of relative positions will not essentially contribute to animprovement in our knowledge of double star orbits.
| Mesures d'etoiles doubles faites a Nice, etoiles doubles nouvelles (24eme serie) decouvertes a Nice.
Table 1 gives 1182 measurements of 682 binaries observed with the 74 and50 cm refractors. Table 2 lists 26 new binaries discovered with the 50cm refractor.
| Radial velocity measurements of visual binary stars
Observations on a correlation radial spectrometer of 31 visual binarysystems with components of late-type spectral classes are reported. Theobservations were made in order to resolve the 180-deg ambiguity of thelongitude of the ascending node. For 11 systems with angular separationsgreater than 1.5 arcsec, the components' velocities were measuredseparately. For 12 systems with angular separations in the range 0.2-1.5arcsec, the sign of radial velocity was obtained with the differentialobservation method. Additional spectroscopic components were detected inthree systems. On the basis of the observations, the true ascending nodeof the orbit was determined for 16 systems. The velocities of the otherfive systems were measured without resolution into components.
| Observations of double stars and new pairs. XV
The study reports visual and photographic measures listed for 1150 pairsobtained in the time frame 1989.91-1992.15, including 221 new doublestars. Magnitudes were estimated for a part of the objects, especiallythe fainter ones. Plate orientations were calculated from field stars ofknown positions and were precessed to the epoch; numbers of nights andof measured exposures are given. Reobservation of faint, neglected pairsreveal many corrections to the data from the old discovery lists.
| A preliminary compilation of DS-programme star positions
A catalog is presented of the double-star-program (DS-program) starpositions, listing right ascensions for 930 DSs and declinations for1225 DSs of the program. The positions were compiled from the observedvalues obtained between 1980 and 1987 with the meridian circles of sixUSSR observatories (the Moscow, Kazan', Kiev, Khar'kov, Odessa, andTashkent Observatories) and the Belgrade Observatory. The measurementsand the treatment of the observational material were performed using therelative method, and the FK-4 system stars were used as reference stars.
| 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.
| Preliminary Version of the Third Catalogue of Nearby Stars
Not Available
| The chromospheric emission-age relation for stars of the lower main sequence and its implications for the star formation rate
An attempt is made to formulate the relationship between age andchromospheric emission (CE) in late-type dwarf stars. Evidence isreviewed that a deterministic relationship of this type actually exists,and that for stars of known age, either a power-law relation or a curvecorresponding to a constant star formation rate fits equally well.Further observations should be able to demonstrate either that there isa real excess of young stars near the sun or that the evolution of CEfor a low-mass star goes through a slow initial decline, a rapid declineat intermediate ages, and finally a slow decline for old stars like thesun.
| Absolute far-ultraviolet spectrophotometry of hot subluminous stars from Voyager
Observations, obtained with the Voyager ultraviolet spectrometers, arepresented of absolute fluxes for two well-known hot subluminous stars:BD + 28 deg 4211, an sdO, and G191 - B2B, a hot DA white dwarf. Completeabsolute energy distributions for these two stars, from the Lyman limitat 912 A to 1 micron, are given. For BD + 28 deg 4211, a single powerlaw closely represents the entire observed energy distribution. For G191- B2B, a pure hydrogen model atmosphere provides an excellent match tothe entire absolute energy distribution. Voyager absolute fluxes arediscussed in relation to those reported from various sounding rocketexperiments, including a recent rocket observation of BD + 28 deg 4211.
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| קבוצת-כוכבים: | שומר הדובים |
| התרוממות ימנית: | 15h24m30.90s |
| סירוב: | +37°20'52.0" |
| גודל גלוי: | 6.5 |
| מרחק: | 37.286 פארסק |
| תנועה נכונה: | -151.3 |
| תנועה נכונה: | 86.9 |
| B-T magnitude: | 7.731 |
| V-T magnitude: | 7.092 |
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