Simulations of the Comet and Tail of Comet Hyakutake

This image shows the expected appearance of the inner 5 degrees of the tail and coma of C/1996 B2 (Hyakutake). The computations were performed using a Monte-Carlo simulation of isotropic emission of gas and dust from the surface of a non-rotating nucleus (for this simulation). The scaling is appropriate for someone observing from a slightly light-polluted area, and the field of view is about 5 degrees. The angular size of the Moon is shown for comparison. The resolution in the original model is about 2.5 arc minutes (144 arc seconds).

The ion tail is approximated by a rapidly moving, anti-solar stream of gas, and is illustrated by the thin faint line. The gas in the gas is assumed to be diatomic carbon (C2). The sharp ``edge'' in the dust tail has been observed, and can be followed directly into the stellar nucleus at higher magnifications.

The model assumes a r^-2 production rate for the gas and dust, a size distribution for the dust with a four order of magnitude range in sizes (although parameterized by the ratio of the radiation force to gravitational force), the ejection velocity is size dependent, but the light scattering is independent of the size. The gas is modeled as photofragments of a parent molecule, and also includes the effects of radiation pressure. Note that the relative orientation of the high radiation pressure ion tail, the intermediate radiation pressure gas coma, and the low radiation pressure dust is maximized on 3/26.

 David Lien Department of Physics Bucknell University Lewisburg, PA 17837 lien@bucknell.edu 

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