The initial physical conditions of the Orion BN/KL fingers
  Orion BN/KL is an example of a poorly understood phenomena in star forming
regions involving the close encounter of young stellar objects. The explosive
structure, the great variety of molecules observed, the energy involved in the
event and the mass of the region suggest a contribution in the {chemical
diversity} of the local interstellar medium. Nevertheless, the frequency and
duration of other events like this have not been determined. In this paper, we
explore a recent analytic model that takes into account the interaction of a
clump with its molecular environment. We show that the widespread kinematic
ages of the Orion fingers -- 500 to 4000 years -- is a consequence of the
interaction of the explosion debris with the surrounding medium. This model
explains satisfactorily the age discrepancy of the Orion fingers, and infers
the initial conditions together with the lifetime of the explosion. Moreover,
our model can explain why some CO streamers do not have a H$_2$ finger
associated.
