The Shapes of Molecular Cloud Cores in Simulations and Observations

TL;DR

This paper compares simulated and observed molecular cloud core shapes, finding high similarity and questioning the role of magnetic fields in core morphology based on shape distributions.

Contribution

It demonstrates that non-magnetic hydrodynamic simulations can replicate observed core shapes, challenging previous assumptions about magnetic field influence.

Findings

Simulations and observations show high statistical similarity in core shapes.

Protostellar and starless cores have similar shape distributions.

Magnetic fields may not significantly influence core shapes as previously thought.

Abstract

In this study, we investigate the shapes of starless and protostellar cores using hydrodynamic, self-gravitating adaptive mesh refinement simulations of turbulent molecular clouds. We simulate observations of these cores in dust emission, including realistic noise and telescope resolution, and compare to the observed core shapes measured in Orion by Nutter & Ward-Thompson (2007). The simulations and the observations have generally high statistical similarity, with particularly good agreement between simulations and Orion B. Although protostellar cores tend to have semi-major axis to semi-minor axis ratios closer to one, the distribution of axis ratios for starless and protostellar cores are not significantly different for either the actual observations of Orion or the simulated observations. Because of the high level of agreement between the non-magnetic hydrodynamic simulations and observation, contrary to a number of previous authors, one cannot infer the presence of magnetic fields from core shape distributions.