The flaming star, runaway stars and ancient collisions in Orion


Image credit: APOD and copyright

AE Aurigae is a hot, blue runaway star which shares with μ Columbae an origin in a gravitational interaction between two massive binaries 2.5 Myr ago in the Orion nebula, near the present location of the Trapezium cluster. The two binaries are thought to have exchanged partners, dynamically ejecting the two runaways and leaving behind the odd eccentric spectroscopic binary ι Orionis. The two runaways are moving away from Orion with equal velocities in opposite directions. Another runaway star, 53 Arietis, was also ejected from Orion but likely in an earlier event.

Recently, a pulsar has been found which can be kinematically traced back to the Upper Scorpius OB association, to an event which also gave rise to the famous runaway star zeta Ophiuchi. This event is thought to have been precipitated by the supernova explosion itself dissociating the previously existing binary pair. The bow shock seen below is created as ζ Oph ploughs through the interstellar medium at 24 kilometers per second. Quoting Hoogerwerf et al. 2000:

These two cases provide the first specific kinematic evidence that both mechanisms proposed for the production of runaway stars, the dynamical ejection scenario and the binary-supernova scenario, operate in nature.

Image credit: APOD, NASA, JPL, Spitzer


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