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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.
| Spectral classification of stars with the same colours in intermediate multiband photometry - The concept of photometric 'star-box'
The concept of a photometric 'star box' is introduced for use with the UB V B1 B2 V1 G photometric system. Star boxes are employed to grouptogether all stars for which each photometric color differs by less thansome small quantity (in magnitude) from the corresponding color of agiven 'central' star. Probable causes of differences between the colorsof two stars are summarized, scatter in spectral type and luminosityclass within a single box is discussed, and the standard deviation ofnarrow-band photometric indices is calculated for stars grouped in thesame box. Dispersions in the UV and IR energy distributions of stars inthe same box are examined, and the results obtained in the seven-colorphotometric system for 113 stars are compared with the correspondingresults in a thirteen-color system. The classification of Am and Am:stars is briefly examined on the basis of star boxes.
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | דג זהב |
| התרוממות ימנית: | 04h19m38.71s |
| סירוב: | -50°57'23.8" |
| גודל גלוי: | 8.659 |
| מרחק: | 100.908 פארסק |
| תנועה נכונה: | 11.5 |
| תנועה נכונה: | 47.1 |
| B-T magnitude: | 9.153 |
| V-T magnitude: | 8.7 |
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