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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.
| BD+11DEG3953 = V925-AQUILAE
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| Visuelle Beobachtungen von kurzperiodischen Veränderlichen.
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| Multicolor television photometry of T Tauri stars. I - Observational technique and preliminary results. II - The nature of variability in T Tauri stars
Results are presented for television observations of 17 T Tauri starsusing a seven-color photometric system. Three types of continuumvariability are distinguished: brightness changes in red light,simultaneous active brightness changes in all spectral regions, andbrightness changes that are more pronounced in the UV than in the redregion. The stars characterized by the first type of variability areshown to have significantly higher bolometric magnitudes than the starsexhibiting the other types, and discrepancies between observed energydistributions and spectral types are tentatively attributed toabsorption of light in circumstellar shells. The absolute energy fluxesemitted by the stellar photospheres in the visible region of thespectrum are calculated along with the Balmer-continuum, H-alpha, andH-beta fluxes originating from the circumstellar gas shells. It is foundthat the type of stellar variability depends on circumstellar-shellluminosity in the Balmer continuum.
| An infrared survey of RW Aurigae stars
An infrared photometric survey of 89 RW Aur type variables in bothhemispheres has been made. JHKL magnitudes and colors are listed. The RWAur variables include a small number of highly reddened late-type stars.All T Tauri and hot Orion population stars show infrared excesses andthe infrared properties mark certain field stars as being young. Thegreatest infrared excesses are found for A and F stars while youngvariable B stars usually show no excesses. The location of the RW Aurstars in the two-color H-K, K-L diagram favor dust re-radiation overfree-free emission as the mechanism responsible for the infrared excess.A weak correlation of H-K with emission class links the occurrence ofcircumstellar dust and gas shells.
| Absolute Proper Motions of 21 Variables of the RW Aur Type.
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