Current theories do not predict how such speeds can be achieved from explosions of supernovas. Some astronomers are toying with the idea that RX J0822-4300 was ejected in one direction during the supernova explosion, while most of the other matter ejected in the opposite direction. However, this idea is only conjecture at the moment.

Winkler states in ScienceDaily.com, "The puzzle about this cosmic cannonball is how nature can make such a powerful cannon. The high speed might be explained by an unusually energetic explosion, but the models are complicated and hard to apply to real explosions."

The research by Winkler and Petre (“Direct Measurement of Neutron Star Recoil in the Oxygen-rich Supernova Remnant Puppis A”) was published in the November 20, 2007 issue of the journal The Astrophysical Journal (Volume 670, Issue 1, Page 635–642, Nov 2007).

Their abstract states, “A sequence of three Chandra X-Ray Observatory High Resolution Camera images taken over a span of five years reveals arcsecond-scale displacement of RX J0822−4300, the stellar remnant (presumably a neutron star) near the center of the Puppis A supernova remnant. We measure its proper motion to be 0.165" ± 0.025" yr⁻¹ toward the west-southwest. At a distance of 2 kpc, this corresponds to a transverse space velocity of ~1600 km s⁻¹. The space velocity is consistent with the explosion center inferred from proper motions of the oxygen-rich optical filaments and confirms the idea that Puppis A resulted from an asymmetric explosion accompanied by a kick that imparted roughly 3×10⁴⁹ ergs of kinetic energy (some 3% of the kinetic energy for a typical supernova) to the stellar remnant. We discuss constraints on core-collapse supernova models that have been proposed to explain neutron star kick velocities.”

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