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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.
| CCD uvbyβ photometry of faint stars. I. Observations and reductions.
An observational programme involving simultaneous CCD- and photoelectricuvbyβ photometry has been carried out using the two Danishtelescopes at La Silla. In order to derive reliable astrophysicalparameters for F dwarfs at distances of several kpc final accuraciesbetter than 0.015mag for each magnitude are needed for faint stars. Highaccuracy requires careful preprocessing and data handling and therequested accuracy is now obtained for stars as faint as V=~18mag usingthe procedure described in this paper. A common robust CCD instrumentalsystem is established and the subsequent transformation to the standardsystem is performed using a set of faint secondary standards observed inthe photoelectric programme. Photoelectric photometry for a number ofcalibration stars in the CCD frames is also published. These stars haveup to 11 observations each and may be included in the preliminary sampleof secondary standards that has emerged from the combined programme.
| Walraven photometry of nearby southern OB associations
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
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