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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.
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| Analysis of the light curves of the eclipsing system V548 Cygni
The eclipsing binary V548 Cygni was observed photoelectrically in B andV colors on 17 nights in 1975 with a 48 cm Cassegrain telescope. Threetimes of minima have been obtained and new light elements have beenderived. Solutions of the light curves have been obtained using themethods of Kitamura (1965) and Wood (1971, 1972, 1973). The system has athird body whose total luminosity is greater than that of secondarycompanion.
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Osservazione e dati astrometrici
| Costellazione: | Cigno |
| Ascensione retta: | 19h56m11.31s |
| Declinazione: | +55°01'24.6" |
| Magnitudine apparente: | 7.841 |
| Distanza: | 165.563 parsec |
| Moto proprio RA: | 1.3 |
| Moto proprio Dec: | -22.9 |
| B-T magnitude: | 8.095 |
| V-T magnitude: | 7.862 |
Cataloghi e designazioni:
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