The Physics of Dust Coagulation and the Structure of Dust Aggregates in Space
C. Dominik, A. G. G. M. Tielens;
ApJ, 1997, 480, 647
ABSTRACT:Even though dust coagulation is a very important dust-processing mechanism in interstellar space and protoplanetary
disks, there are still important parts of the physics involved that are poorly
understood.
This imposes a serious problem for model calculations of any kind.
In this
paper, we attempt to improve the situation by including the effects of
tangential forces on the contact in some detail.
These have been studied in recent
papers.
We summarize the main results from these papers and apply them to detailed
simulations of the coagulation process and of collisions between dust
aggregates.
Our results show the following: (1) the growth of aggregates by monomers
will normally not involve major restructuring of the aggregates, (2) the
classical hit-and-stick assumption is reasonably valid for this case, (3)
collisions of aggregates with each other or with large grains can lead to
significant compaction, and (4) the results can be easily understood in terms of
critical energies for different restructuring processes.
We also derive a
short summary that may be used as a recipe for determining the outcome of
collisions in coagulation calculations.
It is shown that turbulent velocity
fields in interstellar clouds are capable of producing considerably
compressed aggregates, while the small aggregates forming early on in the solar
nebula will not be compacted by collisions.
However, compaction provides an
important energy sink in collisions of larger aggregates in the solar nebula.
KEYWORDS: stars: circumstellar matter, ism: dust, extinction, interplanetary medium, ism: clouds, solar system: formation
PERSOKEY:dust, size distribution, ,
CODE: dominik97