Sourav Chatterjee, Jonathan C. Tan
The Orion Nebula Cluster (ONC) is the nearest region of massive star formation and thus a crucial testing ground for theoretical models. Of particular interest amongst the ONC's ~1000 members are: \theta^1 Ori C, the most massive binary in the cluster with stars of masses 38 and 9 msun (Kraus et al. 2009); the Becklin-Neugebauer (BN) object, a 30 km/s runaway star of ~8 msun (Tan 2004); and the Kleinmann-Low (KL) nebula protostar, a highly-obscured, ~15 msun object still accreting gas while also driving a powerful, apparently ``explosive' outflow (Allen & Burton 1993). The unusual behavior of BN and KL is much debated: How did BN acquire its high velocity? How is this related to massive star formation in the KL nebula? Here we report the results of a systematic survey using ~10^7 numerical experiments of gravitational interactions of the \theta1C and BN stars. We show that dynamical ejection of BN from this triple system at its observed velocity leaves behind a binary with total energy and eccentricity matching those observed for \theta1C. Several other observed properties of \theta1C are also consistent with it having ejected BN and altogether we estimate there is only a ~10^{-5} probability that \theta1C has these properties by chance. Our results suggest that after being launched from \theta1C 4,500 years ago, BN has plowed through the KL massive-star-forming core within the last 1,000 years causing its recently-enhanced accretion and outflow activity.
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http://arxiv.org/abs/1203.0325
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