2019/09/05 by Valentina González Lobos, Vale González Lobos, Amelia M. Stutz
Physics and Astronomy · #Angular velocity #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Centroid #Classical mechanics #Flow velocity #Galaxy #Galaxy rotation curve #Geometry #Line (geometry) #Mach number #Mechanics #Orion Nebula #Physics #Protein filament #Rotation (mathematics) #Spectral line #Stars #Stellar, planetary, and galactic studies #Supersonic speed #Thermal velocity #Velocity dispersion #Velocity gradient #astro-ph.GA
paper · pdf · doi:10.1093/mnras/stz2512
13 pages, 8 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journal
arxiv created 2019/09/05 · openalex publication_date 2019/09/05 · arxiv updated 2019/09/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
ABSTRACT We present analysis of the gas kinematics of the integral-shaped filament (ISF) in Orion A using four different molecular lines, 12CO (1−0), 13CO (1−0), NH3 (1,1), and N2H+ (1−0). We describe our method to visualize the position–velocity (PV) structure using the intensity-weighted line velocity centroid, which enables us to identify structures that were previously muddled or invisible. We observe a north-to-south velocity gradient in all tracers that terminates in a velocity peak near the centre of the Orion Nebula Cluster (ONC), consistent with the previously reported ‘wave-like’ properties of the ISF. We extract the velocity dispersion profiles and compare the non-thermal line widths to the gas gravitational potential. We find supersonic Mach number profiles, yet the line widths are consistent with the gas being deeply gravitationally bound. We report the presence of two 12CO velocity components along the northern half of the ISF; if interpreted as circular rotation, the angular velocity is ω =1.4 \rm Myr-1. On small scales we report the detection of N2H+ and NH3 ‘twisting and turning’ structures, with short associated time-scales that give the impression of a torsional wave. Neither the nature of these structures nor their relation to the larger scale wave is presently understood.