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Keck Interferometer Observations of Classical and Weak-line T Tauri Stars
We present observations of the T Tauri stars BP Tau, DG Tau, DI Tau, GMAur, LkCa 15, RW Aur, and V830 Tau, using long baseline infraredinterferometry at K band (2.2 μm) from the Keck Interferometer. Thetarget sources have a range of mass accretion rates and excessnear-infrared emission. The interferometer is most sensitive to extendedemission on characteristic size scales of 1-5 mas. All sources showevidence for resolved K-band emission on these scales, although a few ofthe sources are marginally consistent with being unresolved. Wecalculate the infrared excess based on fitting stellar photospheremodels to the optical photometry and estimate the physical size of theemission region using simple geometric models for the sources with asignificant infrared excess. Assuming that the K-band-resolved emissiontraces the inner edge of the dust disk, we compare the measuredcharacteristic sizes to predicted dust sublimation radii and find thatthe models require a range of dust sublimation temperatures and possiblyoptical depths within the inner rim to match the measured radii.
| Observations of DG Tauri with the Keck Interferometer
We present the first science results from the Keck Interferometer, adirect-detection infrared interferometer utilizing the two 10 m Kecktelescopes. The instrument and system components are briefly described.We then present observations of the T Tauri object DG Tau, which isresolved by the interferometer. The resolved component has a radius of0.12-0.24 AU, depending on the assumed stellar and extended componentfluxes and the model geometry used. Possible origins and implications ofthe resolved emission are discussed.
| 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.
| Photoelectric Observations of Stars near Northern Hemisphere Selected Areas
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