1999/08/04 by J. -K. Lee, J.-K. Lee, Michael Burton +1 · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Atmospheric Ozone and Climate #Classical mechanics #Infrared #Motion (physics) #Physics #Proper motion #Stars #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.2000.03345.x
published as Mon.Not.Roy.Astron.Soc. 315 (2000) 11 · 9 pages, 8 figures
arxiv created 1999/08/04 · openalex publication_date 2000/06/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We report the first infrared proper motion measurements of the Herbig—Haro objects in OMC-1 using a 4-yr time baseline. The [Fe ii]-emitting bullets are moving of the order of 0.08 arcsec per year, or at about 170 km s− 1. The direction of motion is similar to that inferred from their morphology. The proper motions of H2-emitting wakes behind the [Fe ii] bullets, and of newly found H2 bullets, are also measured. H2 bullets have smaller proper motion than [Fe ii] bullets, while H2 wakes with leading [Fe ii] 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 [Fe ii] 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 100 yr. The most distant bullets have, on average, larger proper motions, but are not consistent with free expansion. Nevertheless, an impulsive, or short-lived (< < 1000 yr), duration for their origin seems likely.