Infrared spectrophotometry of Comet IRAS-Araki-Alcock (1983d): a bare nucleus revealed? |
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| Authors: | MS Hanner DK Aitken R Knacke S McCorkle PF Roche AT Tokunaga |
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| Institution: | Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA;Physics Department (RAAF Academy), Melbourne University, Parkville, Victoria 3052, Australia;Earth and Space Science Department, State University of New York, Stony Brook, New York 11794, USA;Earth and Space Science Department, State University of New York, Stony Brook, New York 11794, USA;Anglo-Australian Observatory, P.O. Box 296, Epping, New South Wales 2121, Australia;Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822, USA |
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| Abstract: | Spectra of the central core and surrounding coma of Comet IRAS-Araki-Alcock (1983d) were obtained at 8–13 μm on 11 May and 2–4 μm on 12 May 1983. Spatially resolved measurements at 10 μm with a 4-arcsec beam showed that the central core was more than 100 times brighter than the inner coma only 8 arcsec away; for radially outflowing dust, the brightness ratio would be a factor of 8. The observations of the central core are consistent with direct detection of a nucleus having a radius of approximately 5 km. The temperature of the sunlit hemisphere was > 300 K. Spectra of the core are featureless, while spectra of the coma suggest weak silicate emission. The spectra show no evidence for icy grains. The dust producton rate on 11.4 May was ～ 105 g/sec, assuming that the gas flux from the dust-producing areas on the nucleus was ～ 10?5 g/cm2/sec. |
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