The CARMA-NRO Orion Survey: Filament Formation via Collision-induced Magnetic Reconnection—the Stick in Orion A
Mairs, Steve; Nakamura, Fumitaka; Klessen, Ralf S.; Bally, John; Goodman, Alyssa; Smith, Rowan J.; Arce, Héctor G.; Carpenter, John M.; Kong, Shuo; Ossenkopf-Okada, Volker; Lis, Dariusz C.; Sánchez-Monge, Álvaro; Schilke, Peter; McGehee, Peregrine; Suri, Sümeyye; Maureira, María José
United States, Germany, Chile, Japan, United Kingdom
Abstract
A unique filament is identified in the Herschel maps of the Orion A giant molecular cloud. The filament, which we name the Stick, is ruler-straight and at an early evolutionary stage. Transverse position-velocity diagrams show two velocity components closing in on the Stick. The filament shows consecutive rings/forks in C18O (1-0) channel maps, which is reminiscent of structures generated by magnetic reconnection. We propose that the Stick formed via collision-induced magnetic reconnection (CMR). We use the magnetohydrodynamics code Athena++ to simulate the collision between two diffuse molecular clumps, each carrying an antiparallel magnetic field. The clump collision produces a narrow, straight, dense filament with a factor of >200 increase in density. The production of the dense gas is seven times faster than freefall collapse. The dense filament shows ring/fork-like structures in radiative transfer maps. Cores in the filament are confined by surface magnetic pressure. CMR can be an important dense-gas-producing mechanism in the Galaxy and beyond.