Vol. 647
5. Galactic structure, stellar clusters and populations

3D dynamics of the Orion cloud complex. Discovery of coherent radial gas motions at the 100-pc scale

by J. Grossschedl, J. Alves, S. Meingast, G. Herbst-Kiss 2021, A&A, 647, A91 alt

The Orion complex is one of the nearest and largest collections of molecular clouds actively forming stars in the Milky Way. New observations using the proper motions of young stellar objects, as measured by Gaia and combined with gas radial velocities from CO archival data, helped to map the gas and stars in this region. They measured the 3D dynamics of a large area (~250 square degrees) across the Orion cloud complex, which includes Orion A, Orion B, and a couple of outer cometary clouds. The authors report the main discovery of coherent radial gas motions at large scales (~100 pc). Also, the energetics make it necessary to have the input of several past supernovae in the region. This is important for the formation history and the subsequent evolution of the young stellar objects in large molecular clouds, including a test for the classical feedback-driven scenario.