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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.
| Photometric and spectroscopic analysis of high Galactic latitude molecular clouds. I - Distances and extinctions of stars toward 25 selected regions
The paper presents new photoelectric photometry in the UBV, uvby, andH-beta systems for 320 stars at high Galactic latitudes, selected fortheir proximity to the densest portions of a variety of high Galacticlatitude atomic and molecular clouds. Low-resolution digital spectra areemployed to classify 115 of the stars. Several novel techniques aredeveloped for automatic digital spectral classification, and fordereddening Stromgren uvby-beta and Johnson UBV,H-beta photometry. Anempirical determination of the errors in the derived dereddened colors,and techniques for converting between the two photometric systems arepresented on the basis of the analysis of a statistically significantsample of 1480 stars with complete data sets in both photometric systemsand with an accurate MK spectral type. New constraints on the distancesto several clouds are presented.
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Saat |
| Sað Açýklýk: | 04h16m52.74s |
| Yükselim: | -48°30'56.6" |
| Görünürdeki Parlaklýk: | 8.125 |
| Uzaklýk: | 113.379 parsek |
| özdevim Sað Açýklýk: | 7 |
| özdevim Yükselim: | 17.3 |
| B-T magnitude: | 8.491 |
| V-T magnitude: | 8.156 |
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