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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
| The Hamburg/RASS Catalogue of optical identifications. Northern high-galactic latitude ROSAT Bright Source Catalogue X-ray sources
We present the Hamburg/RASS Catalogue (HRC) of optical identificationsof X-ray sources at high-galactic latitude. The HRC includes all X-raysources from the ROSAT Bright Source Catalogue (RASS-BSC) with galacticlatitude |b| >=30degr and declination delta >=0degr . In thispart of the sky covering ~ 10 000 deg2 the RASS-BSC contains5341 X-ray sources. For the optical identification we used blue Schmidtprism and direct plates taken for the northern hemisphere Hamburg QuasarSurvey (HQS) which are now available in digitized form. The limitingmagnitudes are 18.5 and 20, respectively. For 82% of the selectedRASS-BSC an identification could be given. For the rest either nocounterpart was visible in the error circle or a plausibleidentification was not possible. With ~ 42% AGN represent the largestgroup of X-ray emitters, ~ 31% have a stellar counterpart, whereasgalaxies and cluster of galaxies comprise only ~ 4% and ~ 5%,respectively. In ~ 3% of the RASS-BSC sources no object was visible onour blue direct plates within 40\arcsec around the X-ray sourceposition. The catalogue is used as a source for the selection of(nearly) complete samples of the various classes of X-ray emitters.
| Binary Star Orbits. II. Preliminary First Orbits for 117 Systems
Orbital elements are presented for 117 binary systems with no previousorbit calculation. For nearly all of these systems, these elements mustbe regarded as preliminary, but the ephemerides presented here should berelatively accurate over the next several decades. Further, the analysisof these systems should highlight the need for their continuedobservation by dedicated programs to improve the veracity of theseelements.
| 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.
| 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.
| The ROSAT Bright Survey: II. Catalogue of all high-galactic latitude RASS sources with PSPC countrate CR > 0.2 s-1
We present a summary of an identification program of the more than 2000X-ray sources detected during the ROSAT All-Sky Survey (Voges et al.1999) at high galactic latitude, |b| > 30degr , with countrate above0.2 s-1. This program, termed the ROSAT Bright Survey RBS, isto more than 99.5% complete. A sub-sample of 931 sources with countrateabove 0.2 s-1 in the hard spectral band between 0.5 and 2.0keV is to 100% identified. The total survey area comprises 20391deg2 at a flux limit of 2.4 x 10-12 ergcm-2 s-1 in the 0.5 - 2.0 keV band. About 1500sources of the complete sample could be identified by correlating theRBS with SIMBAD and the NED. The remaining ~ 500 sources were identifiedby low-resolution optical spectroscopy and CCD imaging utilizingtelescopes at La Silla, Calar Alto, Zelenchukskaya and Mauna Kea. Apartfrom completely untouched sources, catalogued clusters and galaxieswithout published redshift as well as catalogued galaxies with unusualhigh X-ray luminosity were included in the spectroscopic identificationprogram. Details of the observations with an on-line presentation of thefinding charts and the optical spectra will be published separately.Here we summarize our identifications in a table which contains opticaland X-ray information for each source. As a result we present the mostmassive complete sample of X-ray selected AGNs with a total of 669members and a well populated X-ray selected sample of 302 clusters ofgalaxies with redshifts up to 0.70. Three fields studied by us remainwithout optical counterpart (RBS0378, RBS1223, RBS1556). While the firstis a possible X-ray transient, the two latter are isolated neutron starcandidates (Motch et al. 1999, Schwope et al. 1999).
| Common proper motion stars in the AGK 3
A search was made of common-proper-motion (CPM) systems among AGK 3stars. The selection of physical systems was based upon the ratiobetween the angular separation (rho) and the proper motion (mu); the CPMstars found are presented in two tables. Table I lists systems withrho/mu less than 1000 years. It contains 326 entries, and the proportionof optical pairs is estimated to be 1 percent. Table II lists systemswith rho/mu in the range 1000 to 3500 years; it contains 113 systems,but only 60 percent of them are physical. Nevertheless, these systemsoften have separations larger than 10,000 AU and are the mostinteresting for the study of the tail of the distribution function ofthe semimajor axes.
| 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.
| Double star measures at Lick Observatory, Mount Hamilton, California.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978PASP...90..465H&db_key=AST
| Micrometric Measures of Double Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974ApJS...28..413V&db_key=AST
| Mesures d'étoiles doubles faites à l'équatorial de 38 CM de l'Observatoire de Paris
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&AS....6..147B&db_key=AST
| Mikrometermessungen von Doppelsternen. V
Not Available
| Measures of 313 doubles stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1963AJ.....68..114W&db_key=AST
| Measures of Double Stars
Not Available
| Mesures d'étoiles doubles effectuées au réfracteur de 38 cm. de l'Observatoire de Nice
Not Available
| Mesures photométriques d'Etoiles Doubles au télescope de 0. 80 m. de l'Observatoire de Hauteprovence
Not Available
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Osservazione e dati astrometrici
| Costellazione: | Orsa Maggiore |
| Ascensione retta: | 11h38m57.21s |
| Declinazione: | +41°08'34.8" |
| Magnitudine apparente: | 8.059 |
| Distanza: | 73.584 parsec |
| Moto proprio RA: | -80.5 |
| Moto proprio Dec: | -38.3 |
| B-T magnitude: | 8.613 |
| V-T magnitude: | 8.105 |
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