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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
| Medium-Resolution Stellar Spectra in the L Band from 2400 to 3000 cm-1 (3.3 to 4.2 Microns)
We present a brief atlas of L-band (3.3-4.2 μm) spectra for 42 starsplus the Sun and a sunspot observed at a resolving power of R~3000. Thiscontribution is intended to supplement our previous K-band, H-band, andJ-band spectral atlases. The L-band data, which cover some or all of the2400 to 3000 cm-1 (3.3-4.2 μm) region, are mainly forluminous late-type stars. In reducing these data, special care has beentaken to remove telluric features, especially water vapor. We identifytemperature- and luminosity-sensitive atomic and molecular indices toaid in the classification of stellar spectra in the L band. The data areavailable electronically.
| Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
| Meridian observations made in Brorfelde (Copenhagen University Observatory) 1975-76.
This catalogue presents positions for selected faint stars mainly fromAGK3 observed with the 7" transit circle at Brorfelde. The stars aredistributed in 43 selected areas around radio sources and are suitableas reference stars for measuring the optical counterparts to the radiosources. The obscr 'itioi cre carried out from 1975.16 to 1976.04, andevery star was observed at least two times giving a m.s.e. of "13 forthe catalogue positions given in the FK4 system. These positions usedtogether with AGK3 proper motions will in the period 1975 to 1980 have am.s.e. at the epoch ranging from `:13 to `:15, which is less than halfof what is expected when using AGK3 positions. Key words: transit circle- catalogue of positions
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Группы:
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Наблюдательные данные и астрометрия
| Созвездие: | Рыбы |
| Прямое восхождение: | 01h26m54.86s |
| Склонение: | +26°30'47.6" |
| Видимая звёздная величина: | 8.608 |
| Собственное движение RA: | 66.4 |
| Собственное движение Dec: | 9.3 |
| B-T magnitude: | 9.211 |
| V-T magnitude: | 8.658 |
Каталоги и обозначения:
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