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Re: (meteorobs) Asteroids, comets and shedding.
With regard to these questions, cometary nuclei appear to be largely icy
material throughout and are not currently believed to have solid cores.
However, in the process of outgassing a very dark and presumably thin mantle
or residue tends to slowly cover the surface. Outgassing vents or active
regions most definitely have life spans, although they may extend over
centuries. If the comet should have only one active vent, once it is depleted
the object becomes inert and will present largely the appearance of an
asteroidal body. This phase can perhaps last thousands of years. But if, for
thermal or mechanical reasons, an opening is produced in the inert surface,
the object will once more return to being an active comet.
Thus, a currently inactive comet, looking much like an asteroid (except
perhaps spectroscopically), can have an associated meteor stream.
However...if I recall correctly, in the specific case of the parent object of
the Geminids it does appear to have the spectroscopic signature of a true
asteroid (of some class or other). Just the same, there are a number of other
small asteroidal bodies known that are traveling in comet-like orbits and at
least some are probably currently inert cometary nuclei.
jbortle
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