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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.
| Optical images of MCLD123.5+24.9: a cloud illuminated by the North star?
We present B R I images of a 1degr {x}1degr field centered on themolecular cloud (MCLD123.5+24.9) located in the large infrared cirrusknown as the Polaris Flare. The optical images are compared with IRASimages and an extinction map derived from stellar reddenings. We analysethe possibility for the North star (HD8890), only 1degr North of thefield, to be the source of MCLD123.5+24.9 optical emission. For widelyaccepted values of the dust albedo (omega = 0.6) and the assymetryparameter of the Henyey Greenstein phase function (0.7
| Fast digital spectrophometry of celestial bodies
An original digital slitless spectrophotometer with transparentdiffraction gratings has constructed, adjusted, and tested at theCrimean Astrophysical Observatory. It is mounted on the 0.5-m meniscustelescope, has high sensitivity, and enables spectrophotometricobservations of celestial bodies in the region 370-740 nm with exposureof several minutes and absolute photometric accuracy of several percent.The spectrophotometer is intended for studies of rapid variations in thespectra of stars, asteroids, comet nuclei, bright galactic nuclei, etc.
| Regional Spectrophotometric Standards of Intermediate Brightness - Standards around the Northern Celestial Pole
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| Meridian observations made with the Carlsberg Automatic Meridian Circle at Brorfelde (Copenhagen University Observatory) 1981-1982
The 7-inch transit circle instrument with which the present position andmagnitude catalog for 1577 stars with visual magnitudes greater than11.0 was obtained had been equipped with a photoelectric moving slitmicrometer and a minicomputer to control the entire observationalprocess. Positions are reduced relative to the FK4 system for each nightover the whole meridian rather than the usual narrow zones. Thepositions of the FK4 stars used in the least squares solution are alsogiven in the catalog.
| The reddening of Polaris
The B-V color excess of Polaris is obtained by using uvby-betaphotometry of 11 field stars within 0.75 deg of arc of Polaris anddereddening the field stars with the various color calibrations of theStromgren system. An apparent distance of 109 pc is estimated forPolaris, and a color excess of E(B-V) equals 0.02 + or - 0.02 is found.This result is taken as supporting the claims that Polaris is unreddenedor at worst very slightly reddened and therefore lies on the red edge ofthe Cepheid instability strip, as is expected for a small-amplitudeCepheid.
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Membre dels grups següents:
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Dades d'Observació i Astrometria
| Constel·lació: | Cepheus |
| Ascensió Recta: | 02h34m32.67s |
| Declinació: | +88°28'15.7" |
| Magnitud Aparent: | 8.14 |
| Distancia: | 154.083 parsecs |
| Moviment propi RA: | 53.6 |
| Moviment propi Dec: | -48.2 |
| B-T magnitude: | 8.459 |
| V-T magnitude: | 8.167 |
Catàlegs i designacions:
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