APPLIED
KINETIC EQUATIONS
Kinetic models for astrophysics
A joint research project with GIFCO (Italian Group of Cosmic
Physics) lead to study some applications of kinetic equations to
the physics of interstellar matter.
The interstellar matter is composed by molecular and/or atomic
gases as well as by solid dust grains, and it usually forms
clouds that occupy wide regions of the empty space. Such
interstellar clouds have a complex dynamics that involves self-gravitation,
interaction with light, chemical reactions and coagulation/fragmentation
processes. They occupy a preminent position in modern
astrophysics since they play a crucial role in the formation of
stars and planets.
Many mathematical models of the physics of interstellar clouds
are present in literature. Our aim is to investigate the role of
kinetic equations in the description of the various processes
that take place within them.
Radiative transfer in random media
A typical interstellar cloud shows a non-homogeneous structure
with randomly-distributed clumps, i.e., small and dense
"cloudlets". A correct estimation of the UV radiation
field within the cloud is crucial to forecast the chemical
evolution of the cloud. We developed a "finite parameter"
probabilistic description of a clumpy cloud and investigated the
consequent mathematical model. A particular effort has been made
to find an efficient way for estimating the expected value of the
radiation field. Future developments will concern both the
numerical implementation of our method and its theoretical
improvement.
The investigation of radiative transfer in random media is of
interest not only in the interstellar matter physics but also in
other scientific and technological fields such as reactor physics,
metereology and medical physics.
Dust coagulation
According to experimental descriptions, a kinetic model of
dust coagulation has been developed that accounts for the
presence of two populations of dust grains, with
differnt sizes. The model predicts a sweeping out of small
particles by the large ones on a time scale that turns out to be
in good agreement with the observed value. Future developments
will regard the introduction of more complete models as well as
numerical implementation.
Last Updated: 27 september 2000 by Giovanni Frosali