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Near-Infrared Coronagraphic Observations of the T Tauri Binary System UY Aur
We present a near-infrared image of UY Aur, a 0.9" separated binarysystem, using the Coronagraphic Imager with Adaptive Optics on theSubaru Telescope. Thanks to adaptive optics, the spatial resolution ofour image was ~0.1" in the full width at half-maximum of thepoint-spread function, the highest achieved. By comparison with previousmeasurements, we estimated that the orbital period is ~1640+/-90 yr andthe total mass of the binary is ~1.73+/-0.29 Msolar. Theobserved H-band magnitude of the secondary varies by as much as 1.3 magwithin a decade, while that of the primary is rather stable. Thisinconstancy may arise from photospheric variability caused by an unevenaccretion rate or from the rotation of the secondary. We detected ahalf-ring-shaped circumbinary disk around the binary with a brightsouthwestern part but a barely detectable northeastern portion. Thebrightness ratio is >~57+/-5. Its inner radius and inclination areabout 520 AU and 42deg+/-3deg, respectively. Thedisk is not uniform but has remarkable features, including a clumpystructure along the disk, circumstellar material inside the innercavity, and an extended armlike structure. The circumstellar materialinside the cavity probably corresponds to a clump or material accretingfrom the disk onto the binary. The armlike structure is part of thedisk, created by accretion from the outer region of the disk orencounters with other stellar systems.Based on data collected at the Subaru Telescope, which is operated bythe National Astronomical Observatory of Japan.
| 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.
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