EPoS Contribution
EPoS Contribution
The Orion A 3D shape and dynamics: Testing external influences with simulations

Gabor Herbst-Kiss
U Vienna, Vienna, AT
The surprising 3D shape of the Orion A molecular cloud as revealed from Gaia, with a dense and star-formation rich "bent head" (the ONC region) and a star-formation poor "tail" (L1641), which is almost orthogonal to the plane of the sky, strongly suggest the presence of an external agent, either caused a cloud-cloud collision, or feedback from massive stars (stellar winds or supernovae). In this presentation we test scenarios responsible for this cloud's 3D shape using the smooth particle hydrodynamics (SPH) code GANDALF. The initial setup is an inclined cylindrical cloud representing the unaltered Orion A cloud. A frontal collision with various sized clouds is then studied in a first cloud-cloud collision scenario. In a second scenario we simulate a Supernova explosion taking place in front of the cylindrical cloud. We present the results of the simulations and determine the likelihood of each scenario by comparing results with the observed shape and dynamics of the Orion A cloud, as seen from Gaia and molecular-line work. We conclude that supernovae feedback is likely the main culprit behind the observed cloud properties, including the higher star formation rate near the head of the cloud, likely the closest region to the source of feedback.
Caption: Column density plot of preliminary result of a Supernova simulation and cylindrical filament at t = 5.96. The view is from top down at the elongated Orion A structure. The Supernova started at t=0.00 at X,Y,Z = 0. The first star formation sets in at the head of the cylindrical structure. Fragmentation is visible along the cylinder. The head of the structure is bent due to the spherical shockwave of the Supernova.
Collaborators:
J. Grossschedl, U Vienna, AT
J. Alves, U Vienna, AT
Suggested Session: Molecular Clouds