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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.
| The Stellar Content of Obscured Galactic Giant H II Regions. I. W43
Near-infrared images of the Galactic giant H II region W43 reveal adense stellar cluster at its center. Broadband JHK photometry of theyoung cluster and K-band spectra of three of its bright stars arepresented. The 2 μm spectrum of the brightest star in the cluster isvery well matched to the spectra of Wolf-Rayet stars of subtype WN7. Twoother stars are identified as O-type giants or supergiants by their NIII and C IV emission. The close spatial clustering of O- and thehydrogen WN-type stars is analogous to the intense starburst clustersR136 in the Large Magellanic Cloud and NGC 3603 in the Galaxy.
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Osservazione e dati astrometrici
| Costellazione: | Balena |
| Ascensione retta: | 01h12m07.81s |
| Declinazione: | -23°25'53.2" |
| Magnitudine apparente: | 9.659 |
| Moto proprio RA: | 24.4 |
| Moto proprio Dec: | 11.2 |
| B-T magnitude: | 10.171 |
| V-T magnitude: | 9.702 |
Cataloghi e designazioni:
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