An orbital release model for the Orion BN/KL fingers

Abstract

ABSTRACT We present a simple model in which the bullets that produce the ‘Orion fingers’ (ejected by the BN/KL object) are interpreted as protoplanets or low-mass protostars in orbit around a high-mass star that has a supernova explosion. As the remnant of the SN explosion has only a small fraction of the mass of the pre-supernova star, the orbiting objects then move away in free trajectories, preserving their orbital velocity at the time of release. We show that a system of objects arranged in approximately coplanar orbits results in trajectories with morphological and kinematical characteristics resembling the Orion fingers. We show that, under the assumption of constant velocity motions, the positions of the observed heads of the fingers can be used to reconstruct the properties of the orbital structure from which they originated, resulting in a compact disc with an outer radius of ∼2.4 au.