Gas Flux of Minor Volatiles from the Inside of a Porous Comet Nucleus
J. Benkhoff (DLR)
Sublimation of minor gases (CO, , )
from ices inside of a porous comet nucleus may be important to explain
activity a larger heliocentric distances (>3 AU) and to understand
observationally results.
A new model to describe the gas flux
inside the porous nucleus more accurately has been developed.
We obtain a set of conservation equations for each of the
different volatiles which are solved simultaneously under appropriate
boundary conditions. As a result, one get the gas flux from volatile,
icy components inside the porous nucleus,
temperature profiles and changes in relative chemical abundances,
porosity and pore size distribution as a function of depth, and the gas
flux into the interior and into the atmosphere for each of the volatiles
at various positions of the comet in its orbit.
From the calculations we derive higher values of the gas flux into
the interior and lower values of the gas flux into the atmosphere than
from our previous models (Benkhoff and Huebner, ICARUS 114, 1995;
Benkhoff and Huebner, Planet. Space Sci.44, 1996 ). Diurnal effects on
the mixing ratio of minor gases to water depend on
the structure of the body and the rotation period.