A 3D View of Orion: I. Barnard’s Loop

Barnard’s Loop is a famous arc of hydrogen-alpha emission located in the Orion star-forming region. Here, we provide evidence of a possible formation mechanism for Barnard’s Loop and compare our results with recent work suggesting a major feedback event occurred in the region around 6 Myr ago. We expand on the discovery of a coherent, radial, 3D expansion of the OBP-Near/Briceño-1 (OBP-B1) cluster at the center of Barnard’s Loop from Swiggum et al. 2021. This cluster appears to serve as another possible center for expansion of a number of young clusters identified in Grosschedl et al. 2021, which previously attributed the expansion center to Orion X. 3D dust mapping is used to characterize the 3D topology of the entire region, which shows Barnard’s Loop’s correspondence to a roughly spherical 3D cavity around the OPB-B1 cluster. Simple estimates of gravitational effects from both stars and gas indicate that gravitational feedback from the gas and dust may have strongly affected the kinematics of the stars in OBP-B1. We conclude that it is likely that at least one supernova occurred in the OBP-B1 cluster and played a major role in shaping the region.