3D Dust Mapping Reveals that Orion Forms Part of a Large Ring of Dust
  The Orion Molecular Complex is the nearest site of ongoing high-mass star
formation, making it one of the most extensively studied molecular complexes in
the Galaxy. We have developed a new technique for mapping the 3D distribution
of dust in the Galaxy using Pan-STARRS1 photometry. We isolate the dust at the
distance to Orion using this technique, revealing a large (100 pc, 14 degree
diameter), previously unrecognized ring of dust, which we term the "Orion dust
ring." The ring includes Orion A and B, and is not coincident with current
H-alpha features. The circular morphology suggests formation as an ancient
bubble in the interstellar medium, though we have not been able to conclusively
identify the source of the bubble. This hint at the history of Orion may have
important consequences for models of high-mass star formation and triggered
star formation.
