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Orbital motion of DF Tauri from speckle interferometry.
We report the evidence of the orbital motion of the binary star DF Tau.This result is obtained from visible speckle interferometry and useslunar occultations of Chen et al. (1990). It is the first step towards adirect determination of the dynamical mass of this young system. Theportion of the orbit covered between the epochs of observation is stilltoo small (~10%) to allow precise derivation of the orbital elements. Wehowever provide a first estimate of the mass of the system as being2.8+/-1.5M_sun_. We investigate the incidence of the binarity of DF Tauon the modeling of its spectral energy distribution and discuss thenature of the components.
| The Henry Draper Extension Charts: A catalogue of accurate positions, proper motions, magnitudes and spectral types of 86933 stars
The Henry Draper Extension Charts (HDEC), published in the form offinding charts, provide spectral classification for some 87000 starsmostly between 10th and 11th magnitude. This data, being highlyvaluable, as yet was practically unusable for modern computer-basedastronomy. An earlier pilot project (Roeser et al. 1991) demonstrated apossibility to convert this into a star catalogue, using measurements ofcartesian coordinates of stars on the charts and positions of theAstrographic Catalogue (AC) for subsequent identification. We presenthere a final HDEC catalogue comprising accurate positions, propermotions, magnitudes and spectral classes for 86933 stars of the HenryDraper Extension Charts.
| Ultraviolet extinction and diffuse band strength correlations
Correlations between UV extinction parameters and diffuse band strengthsare south, using a data base of 50 stars with recently measuredextinction curves. A novel aspect of this study is that the basicdependence of most interstellar parameters on E(B-V) (or, nearlyequivalently, on the total hydrogen column density) has been largelycanceled out. After this cancellation, a weak correlation is foundbetween the 4430 A diffuse band and the 2175 A extinction feature. Noother correlations are found. These results support a molecular originfor the 5780 A and 6284 A bands. It is speculated that the correlationpattern found for the 4430 A band can be explained if this bandoriginates in reactions on disordered grain surfaces.
| Interstellar extinction in the dark Taurus clouds. I
The results of photoelectric photometry of 74 stars in the Vilniusseven-color system in the area of Taurus dark clouds with coordinates(1950) 4h20m-4h48m +24.5 deg to +27 deg are presented. Photometricspectral types, absolute magnitudes, color excesses, interstellarextinctions and distances of the stars are determined. The dark cloudKhavtassi 286, 278 and the surrounding absorbing nebulae are found toextend from 140 to 175 pc from the sun. The average interstellarextinction on both sides of the dark cloud is of the order of 1.5m. Noevidence of the existence of several absorbing clouds situated atvarious distances is found.
| Photoelectric UBV sequences in Tau.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1967AJ.....72.1012L&db_key=AST
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Osservazione e dati astrometrici
| Costellazione: | Toro |
| Ascensione retta: | 04h32m39.80s |
| Declinazione: | +25°07'21.7" |
| Magnitudine apparente: | 10.06 |
| Moto proprio RA: | 5.7 |
| Moto proprio Dec: | -2.4 |
| B-T magnitude: | 10.459 |
| V-T magnitude: | 10.093 |
Cataloghi e designazioni:
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