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On the Structure of the Orion A Cloud and the Formation of the Orion Nebula Cluster

Lee Hartmann·Andreas Burkert
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Abstract

We suggest that the Orion A cloud is gravitationally collapsing on large scales, and is producing the Orion Nebula Cluster due to the focusing effects of gravity acting within a finite cloud geometry. In support of this suggestion, we show how an elliptical rotating sheet of gas with a modest density gradient along the major axis can collapse to produce a structure qualitatively resembling Orion A, with a fan-shaped structure at one end, ridges or filaments along the fan, and a narrow curved filament at the other end reminiscent of the famous integral-shaped filament. The model produces a local concentration of mass within the narrow filament which in principle could form a dense cluster of stars like that of the Orion Nebula. We suggest that global gravitational contraction might be a more common feature of molecular clouds than previously recognized, and that the formation of star clusters is a dynamic process resulting from the focusing effects of gravity acting upon the geometry of finite clouds.

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Lee Hartmann, Andreas Burkert. 2006-09-25. On the Structure of the Orion A Cloud and the Formation of the Orion Nebula Cluster. https://doi.org/10.1086/509321

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