The ALMA View of the OMC1 Explosion in Orion

John Bally, Adam Ginsburg, Hector Arce, Josh Eisner, Allison Youngblood, Luis Zapata, Hans Zinnecker

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


Most massive stars form in dense clusters where gravitational interactions with other stars may be common. The two nearest forming massive stars, the BN object and Source I, located behind the Orion Nebula, were ejected with velocities of ∼29 and ∼13 km s-1 about 500 years ago by such interactions. This event generated an explosion in the gas. New ALMA observations show in unprecedented detail, a roughly spherically symmetric distribution of over a hundred 12CO J = 2-1 streamers with velocities extending from V LSR = -150 to +145 km s-1. The streamer radial velocities increase (or decrease) linearly with projected distance from the explosion center, forming a "Hubble Flow" confined to within 50″ of the explosion center. They point toward the high proper-motion, shock-excited H2 and [Fe ii] "fingertips" and lower-velocity CO in the H2 wakes comprising Orion's "fingers." In some directions, the H2 "fingers" extend more than a factor of two farther from the ejection center than the CO streamers. Such deviations from spherical symmetry may be caused by ejecta running into dense gas or the dynamics of the N-body interaction that ejected the stars and produced the explosion. This ∼1048 erg event may have been powered by the release of gravitational potential energy associated with the formation of a compact binary or a protostellar merger. Orion may be the prototype for a new class of stellar explosiozn responsible for luminous infrared transients in nearby galaxies.

Original languageEnglish (US)
Article number60
JournalAstrophysical Journal
Issue number1
StatePublished - Mar 1 2017


  • Herbig-Haro objects
  • ISM: individual objects (Orion OMC1)
  • ISM: jets and outflows
  • stars: formation
  • stars: massive

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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