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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.
| A multicolor survey of absolute proper motions: galactic structure and kinematics in the direction of the galactic center at intermediate latitude.
Bienayme et al. (1992) have published a magnitude-limited sample ofproper motions for stars at the intermediate galactic latitude (l=3deg,b=47deg; α_1950_=15h18m, δ_1950_=+02d16') for a 2 squaredegree field. In their study there was a lack of an accurate absoluteastrometric reference due to very small number of galaxies orextragalactic objects in the field. However, since Bienayme et al.paper, more deep photographic plates and CCD standards have beenobtained. Here we have derived a new photographic photometry and propermotions for ~20000 stars with completeness to V~18 in the same directionfor a 15.5 square degree field. The combination of four glass copies ofthe Palomar Observatory Sky Survey (i.e. POSS 1402 E&O and POSS 1429E&O) has been used as a first epoch for proper motion determination.The random error of the proper motions is approximately 0.3"/century toV~17. The photometric accuracy ranges between 0.07 to 0.10 in the V, Band U bands. We stress the importance of the magnitude and color effectsin astrometric surveys of field stars. Using color-magnitude diagrams ofa few cluster member stars, a new distance of 6.9+/-0.5kpc is derivedfor M5 and 20.3+/-0.8kpc for Pal 5 globular clusters. This is in goodagreement with other determinations. We have analyzed the components ofU+W and V galactic space motions resulting from the accurate propermotions survey. No dependence with z distance is found in the asymmetricdrift of the thick disk population. New estimates of the parameters ofthe velocity ellipsoid have been derived for the thin disk, thick diskand halo populations of the Galaxy.
| The interstellar reddening in front of globular clusters.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975PASP...87...65C&db_key=AST
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | נחש |
| התרוממות ימנית: | 15h18m57.58s |
| סירוב: | +04°33'02.2" |
| גודל גלוי: | 8.713 |
| מרחק: | 89.767 פארסק |
| תנועה נכונה: | 61 |
| תנועה נכונה: | -9.8 |
| B-T magnitude: | 9.211 |
| V-T magnitude: | 8.755 |
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