  We propose a new scenario for compound chondrule formation named as
"fragment-collision model," in the framework of the shock-wave heating model. A
molten cm-sized dust particle (parent) is disrupted in the high-velocity gas
flow. The extracted fragments (ejectors) are scattered behind the parent and
the mutual collisions between them will occur. We modeled the disruption event
by analytic considerations in order to estimate the probability of the mutual
collisions assuming that all ejectors have the same radius. We found that the
estimated collision probability, which is the probability of collisions
experienced by an ejector in one disruption event, can account for the observed
fraction of compound chondrules. In addition, the model predictions are
qualitatively consistent with other observational data (oxygen isotopic
composition, textural types, and size ratios of constituents). Based on these
results, we concluded that this new model can be one of the strongest
candidates for the compound chondrule formation.
  It should be noted that all collisions do not necessarily lead to the
compound chondrule formation. The formation efficiency and the future works
which should be investigated in the forthcoming paper are also discussed.
