Cometary Nucleus

Nucleus, Cometary

 

the central part of a comet, which, according to current concepts, consists of water vapor with traces of “ices” of other gases, as well as rocky substances. Together with the nebulous envelope, or coma, the nucleus forms the head of the comet. (See.)

References in periodicals archive ?
It appears that if the cometary nucleus exhibits an unusually slow rotation rate and its surface is suitably microporous, then the melting of water ice is especially favoured at heliocentric distances of 1-3AU, and at 5-12AU hydrocarbons can melt.
The flyby provided a wealth of data for studies of a cometary nucleus.
It is also contributing to a study of the physical properties of the cometary nucleus and surface, inner structure, and tail.
But occasionally a cometary nucleus leaves its fellows and plummets into the inner solar system, where it may come close enough to the Sun for us to designate it as a long-period comet; or else it might make a close pass by one or more of the major planets, and have its orbit progressively altered, so that eventually we describe it as a short-period comet.
Perhaps, it was inferred, Oljato might be an old cometary nucleus that retained only enough of its ices to "outgas' a little in the sun's heat and produce the traces recorded by spacecraft, but not enough to form a more active comet's familiar, fuzzy "coma' and tail.
This tells us this cometary nucleus is fragile and weak based on how subdued the crater is we see today.