Mon. Not. R. Astron. Soc., 315, 11-20 (2000/June-2)
An infrared proper motion study of the Orion bullets.
LEE J.-K. and BURTON M.G.
Abstract (from CDS):
We report the first infrared proper motion measurements of the Herbig-Haro objects in OMC-1 using a 4-yr time baseline. The [Feii]-emitting bullets are moving of the order of 0.08arcsec per year, or at about 170km.s–1. The direction of motion is similar to that inferred from their morphology. The proper motions of H2-emitting wakes behind the [Feii] bullets, and of newly found H2 bullets, are also measured. H2 bullets have smaller proper motion than [Feii] bullets, while H2 wakes with leading [Feii] bullets appear to move at similar speeds to their associated bullets. A few instances of variability in the emission can be attributed to dense, stationary clumps in the ambient cloud being overrun, setting up a reverse-oriented bullet. Differential motion between [Feii] bullets and their trailing H2 wakes is not observed, suggesting that these are not separating, and also that they have reached a steady-state configuration over at least 100yr. The most distant bullets have, on average, larger proper motions, but are not consistent with free expansion. Nevertheless, an impulsive, or short-lived (≪1000yr), duration for their origin seems likely.
2000, Royal Astronomical Society
ISM: individual: OMC-1 - ISM: jets and outflows - infrared: ISM: lines and bands