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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.
| Stellar Companions and the Age of HD 141569 and Its Circumstellar Disk
We investigate the stellar environment of the β Pictoris-like starHD 141569 with optical spectroscopy and near-infrared imaging. The B9.5Ve primary and two other stars (types M2 and M4) both located inprojection less than 9" away have the same radial velocity and propermotion and therefore almost certainly form a triple star system. Fromtheir X-ray flux, lithium absorption, and location on pre-main-sequenceevolutionary tracks, the companions appear to be 5 Myr old. HD 141569Ais now one of the few main-sequence stars with a circumstellar disk thathas a well-determined age. The circumstellar disk is composed ofsecondary debris material, thus placing an upper limit on the timeneeded for disk processing. These three stars may be part of anassociation of young stars.
| Stromgren and H-beta photometry of stars earlier than G0 in 5 areas containing high latitude molecular clouds
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1989A&AS...80..127F&db_key=AST
| A Finding List of Early-Type Stars in Regions of Intermediate Galactic Latitude
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969ApJ...157..327U&db_key=AST
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Terazi |
| Sað Açýklýk: | 15h44m26.29s |
| Yükselim: | -03°50'18.5" |
| Görünürdeki Parlaklýk: | 8.474 |
| Uzaklýk: | 92.593 parsek |
| özdevim Sað Açýklýk: | -27.8 |
| özdevim Yükselim: | -30.5 |
| B-T magnitude: | 8.921 |
| V-T magnitude: | 8.511 |
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