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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.
| Multiple systems of astrophysical interest. III - When is a binary wide?
The possibility that the statistics of wide binaries, used to testtheories of stellar encounters, are biased against large separations isexamined on the basis of known widely spaced systems of objects withcommon space motion. It is possible to conclude that before concepts ofstellar interactions can be quantized both unbiased samples of widebinaries and some knowledge of their ages are necessary.
| HD 138168 and HD 138181, a hard binary?
Relevant physical data for the two F3 stars HD 138168 and HD 138181,which form a typical instance of apparent intermediate configurationbetween double star and cluster, are compared to determine the possibleexistence of significant individual properties. Very little differenceis found between the two stars. The average line depth for HD 138181shows an excess of about three percent in relation to the depth for HD138168, possibly indicating a slight difference in temperature orrotational velocity.
| Concluding observations of loose stellar clusterings in the southern Milky Way
UBV photometry and spectral classification have been performed on 280stars in the Carina-Crux-Centaurus-Norma region, suspected of belongingto poor open clusters or associations. The work is a concluding part ofa large project for detecting and listing of such objects in order toobtain an improved concept about the true frequency of clusterings inthe Milky Way. The result indicates that a majority of the suspectedobjects are members of various types of physical stellar clusterings,occasionally cluster remnants.
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