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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.
| On the Binary Nature of 1RXS J162848.1-415241
We present spectroscopy of the optical counterpart to 1RXSJ162848.1-41524, also known as the microquasar candidate MCQCJ162847-4152. All the data indicate that this X-ray source is not amicroquasar and that it is a single-lined chromospherically activebinary system with a likely orbital period of 4.9 days. Our analysissupports a K3 IV spectral classification for the star, which is dominantat optical wavelengths. The unseen binary component is most likely alate-type (K7-M) dwarf or a white dwarf. Using the high-resolutionspectra, we have measured the K3 star's rotational broadening to bevsini=43+/-3 km s-1 and determined a lower limit to thebinary mass ratio of q(=M2/M1)>2.0. The highrotational broadening together with the strong Ca II H and K/Hαemission and high-amplitude photometric variations indicate that theevolved star is very chromospherically active and responsible for theX-ray/radio emission.
| Photoelectric Photometry of Stars in the Orion Standard Region
Magnitudes and color indices in the Vilnius seven-color photometricsystem are given for 108 stars in the Orion standard region around theOrion Belt and the star lambda Orionis. New spectral and luminosityclasses, estimated from the photometric data, are given for some of thestars.
| 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.
| Redshifts of galaxies in the Fornax cluster
Among the accurate radial velocities presented for 51 galaxies in theFornax cluster, 17 redshifts have been determined for the first time. Across-comparison with prevous data indicates that the quoted mean errorsare truly external ones, with the average mean error for these radialvelocities being 27 km/sec. This accuracy demonstrates the potential forredshift determinations based on use of the ESO's Boller and Chivensspectrographs, together with the IDS.
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| Takýmyýldýz: | Yontar |
| Sað Açýklýk: | 01h02m12.75s |
| Yükselim: | -31°37'23.6" |
| Görünürdeki Parlaklýk: | 8.812 |
| Uzaklýk: | 180.18 parsek |
| özdevim Sað Açýklýk: | 70 |
| özdevim Yükselim: | -19.6 |
| B-T magnitude: | 9.409 |
| V-T magnitude: | 8.862 |
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