The distribution of dust in the inner coma of comet IRAS-Araki-Alcock (1983d) |
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| Institution: | 1. GCAP-CASPER, Physics Department, Baylor University, Waco, TX 76798-7316, USA;2. Department of Astronomy, School of Astronomy and Space Science, University of Science and Technology of China, Hefei, Anhui 230026, China;3. Department of Physics, School of Physical Science and Technology, Ningbo University, Ningbo, Zhejiang 315211, China;4. Institute for Theoretical Physics and Cosmology, Zhejiang University of Technology, Hangzhou 310023, China |
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| Abstract: | High-resolution images of comet IRAS-Araki-Alcock taken on five separate through its closest approach to the Earth are presented. The images were taken in the red and near-infrared, and so consist primarily of continuum scattering from dust grains. The distribution of dust in the inner coma varied widely from day to day, although the dust was emitted primarily in the sunward direction on all days. The main emission exhibited a lag angle consistent with a nuclear rotational vector that was oriented approximately along the line of sight on May 11.3 1983 UT. A curved filament, extending in the sunward direction, was seen in the deepest images obtained on this day as well, and the azimuthal distribution of dust was strongly of dust was strongly peakeed in the sunward direction. The presence of the curved filament is indicative of dust outflow from an active region, on a mantled nucleus. On all days, the brightness falls off slower than the r− expected for uniform outflow, which is interpreted as resulting from fragmentation of the dust grains as they traveled through the coma. The nuclear region appeared stellar on all days. The seeing-limited spatial resolutions was 19 km on May 11.3, but deconvolution of the images with the instrumental profile enables an upper limit of 17 km to be placed on the diameter of the nucleus. |
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