Geometry, Kinematics, and Magnetization of Simulated Prestellar Cores

TL;DR

This study uses 3D MHD simulations to analyze prestellar core properties, revealing that cores are generally triaxial with magnetic fields aligned with their minor axes, challenging classical star formation theories.

Contribution

It provides new statistical insights into core shapes, magnetic field orientations, and angular momentum, contrasting with classical models and aligning with recent observations.

Findings

Cores are predominantly triaxial rather than oblate.

Magnetic fields are mostly parallel to the core's minor axis.

Core angular momentum is misaligned with magnetic fields, consistent with observations.

Abstract

We utilize the more than 100 gravitationally-bound dense cores formed in our three-dimensional, turbulent MHD simulations reported in Chen & Ostriker (2015) to analyze structural, kinematic, and magnetic properties of prestellar cores. Our statistical results disagree with the classical theory of star formation, in which cores evolve to be oblate with magnetic field parallel to the minor axes. Instead, we find that cores are generally triaxial, although the core-scale magnetic field is still preferentially most parallel to the core's minor axis and most perpendicular to the major axis. The internal and external magnetic field directions are correlated, but the direction of integrated core angular momentum is misaligned with the core's magnetic field, consistent with recent observations. The ratio of rotational/total kinetic and rotational/gravitational energies are independent of core size and consistent in magnitude with observations. The specific angular momentum also follows the observed relationship $L/M \propto R^{3/2}$, indicating rotation is acquired from ambient turbulence. With typical $E_\mathrm{rot}/E_K \sim 0.1$, rotation is not the dominant motion when cores collapse.