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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.
| Young, high-velocity stars. I - Rotational velocities and a catalog of early-type stars at the South Galactic Pole
A catalog has been compiled of 305 early-type stars to F0 and 15thmagnitude in 218 sq deg at the South Galactic Pole. Stromgren photometryand medium- and high-resolution spectra for many of the catalog starshave been obtained. Radial velocities, H-beta line widths, Balmer jumps,and Ca II K line equivalent widths have been measured and tabulated.Rotational velocities were obtained for eight distant A stars and arefound to be typical of values for normal young main sequence stars.
| Young, high-velocity a stars. II - Misidentified, ejected, or unique?
The ages, abundances, and kinematics of a large number of early-typestars at the south Galactic pole are derived to examine the properties,augment the sample of high-velocity stars, and study hypothesesconcerning their origin. The results are compared to a group of normal Astars near the disk. It is suggested that at around 6.5 X 10 to the 8thyr ago, a major source of relatively low abundance hydrogen was accretedby the Galactic disk, forming young high-velocity stars that do notpartake of the age-abundance-kinematics relationships shown by otherstellar groupings.
| A finding list of early-type stars near the south galactic pole.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971AJ.....76..338S&db_key=AST
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Balina |
| Sað Açýklýk: | 00h44m51.88s |
| Yükselim: | -20°20'12.4" |
| Görünürdeki Parlaklýk: | 8.927 |
| Uzaklýk: | 177.62 parsek |
| özdevim Sað Açýklýk: | 6.6 |
| özdevim Yükselim: | -37.9 |
| B-T magnitude: | 9.347 |
| V-T magnitude: | 8.962 |
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