Crystallization of amorphous ice as the cause of Comet P/Halley's outburst at 14 AU
Abstract
An explanation is provided for the postperihelion eruption of Comet P/Halley, detected in February 1991 and believed to have started three months earlier, namely, the crystallization of amorphous ice taking place in the interior of the porous nucleus, at depths of a few tens of meters, accompanied by the release of trapped gases. Numerical calculations show that for a bulk density of 0.5 g/cu cm and a pore size of 1 micron crystallization occurs on the outbound leg of Comet P/Halley's orbit, at heliocentric distances between 5 AU and 17 AU. The trapped gas is released and flows to the surface through the porous medium. It may also open wider channels, as the internal pressures obtained surpass the tensile strength of cometary ice. The outflowing gas carries with it grains of ice and dust, and thus can explain the large amounts of dust observed in the coma at 14.3 AU and beyond.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- May 1992
- Bibcode:
- 1992A&A...258L...9P
- Keywords:
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- Amorphous Materials;
- Bursts;
- Comet Nuclei;
- Crystallization;
- Halley'S Comet;
- Ice;
- Gas Evolution;
- Gas Flow;
- Interplanetary Dust;
- Porous Materials;
- Astrophysics