Comets - the Ur-dust of our solar system in the Oort cloud often precipitates into cometissimals, objects about 75m in diameter. The elements in these cometissimals then gravitationlly precipitate, with denser elements slowly moving toward the center of these cometissimals.

These cometissimals then sometimtes combine into larger objects which we call comets. Depending upon when the combination of the cometissimals occured, these comets can be more or less friable or "bound".

If a comet is loosely bound, then a weak gravitational force is sufficient to fragment it; if on the other hand its cometissimals combined longer ago, and are more tightly bound, a greater gravitational force is required. Grvaity appears to be the fragmenting force, not the discharge of surface volatiles.

The x-rays are most likely the result of interaction of the material in the coma with particles from our Sun.