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Effective temperature scale and bolometric corrections from 2MASS photometry
We present a method to determine effective temperatures, angularsemi-diameters and bolometric corrections for population I and II FGKtype stars based on V and 2MASS IR photometry. Accurate calibration isaccomplished by using a sample of solar analogues, whose averagetemperature is assumed to be equal to the solar effective temperature of5777 K. By taking into account all possible sources of error we estimateassociated uncertainties to better than 1% in effective temperature andin the range 1.0-2.5% in angular semi-diameter for unreddened stars.Comparison of our new temperatures with other determinations extractedfrom the literature indicates, in general, remarkably good agreement.These results suggest that the effective temperaure scale of FGK starsis currently established with an accuracy better than 0.5%-1%. Theapplication of the method to a sample of 10 999 dwarfs in the Hipparcoscatalogue allows us to define temperature and bolometric correction (Kband) calibrations as a function of (V-K), [m/H] and log g. Bolometriccorrections in the V and K bands as a function of T_eff, [m/H] and log gare also given. We provide effective temperatures, angularsemi-diameters, radii and bolometric corrections in the V and K bandsfor the 10 999 FGK stars in our sample with the correspondinguncertainties.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| 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 association surrounding NGC 2439
The structure of the field surrounding the Galactic cluster NGC 2439 isstudied utilizing uvbybeta photometry of bright OB stars. We collate allphotometric and kinematic data available to identify possible groupings.The stars of our sample show a large scatter in their distances, radialvelocities, proper motions and reddenings. We conclude that they do notbelong to a single stellar association. We find evidence of theexistence of three coherent structures at distances of 370 pc, 1 kpc,and 2.6-3.2 kpc. The high stellar density toward NGC 2439 is very likelydue to a decreased absorption in this direction, which poses some doubton the reality of the cluster. A comprehensive uvbybeta study of NGC2439 is required to clarify its nature. The spatial distribution of thestars and their reddening are used to characterise the spatialdistribution of the visual extinction in the region. The resultsobtained confirm previously determined constraints on the formationmechanism of interstellar CH+ towards the NGC 2439 field.Table 2 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/372/95
| The extension of the MK spectral classification system to the intermediate population II F type stars
A grid of metal-weak spectral-classification standards is used tosystematically extend the MK spectral-classification system to F-typestars of the intermediate population II. The present method allowsmetal-weak program stars to be compared with standards of similarmetallicity and effective temperature. The results demonstrate that theintermediate population II is very homogeneous. Excellent agreement isobtained between the classifications of the present extended system anduvby-beta photometric results.
| Four-colour UVBY and H-beta photometry of all A3 to F5 stars brighter than m(pg) = about 11.0 mag in 6 Selected Areas close to the Galactic plane
Photometric observations of 540 A3-F5 stars in Selected Areas 171, 173,175, 177, 192, and 195 of the Potsdam survey (Becker and Brueck,1929-1938) are reported. Data obtained in the Stromgren uvby-beta systemusing a 6-channel spectrograph-photometer on the 50-cm Danish telescopeat ESO on 98 nights during 1986-1987 are presented in extensive tablesand graphs and briefly characterized. Comparisons with previousobservations of some program stars reveal no systematic differences inmagnitude or spectral indices.
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Наблюдательные данные и астрометрия
| Созвездие: | Корма |
| Прямое восхождение: | 07h40m30.51s |
| Склонение: | -33°25'34.2" |
| Видимая звёздная величина: | 7.329 |
| Расстояние: | 57.537 парсек |
| Собственное движение RA: | -52 |
| Собственное движение Dec: | 140.1 |
| B-T magnitude: | 7.964 |
| V-T magnitude: | 7.382 |
Каталоги и обозначения:
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