Simulating star formation in molecular cores II. The effects of different levels of turbulence

TL;DR

This study uses SPH simulations to examine how varying turbulence levels influence star formation, core collapse, and fragmentation, revealing that higher turbulence increases object formation and companion frequency, with a bimodal mass function.

Contribution

It provides new insights into the impact of turbulence levels on star formation processes and the resulting mass distribution of stellar objects.

Findings

Higher turbulence leads to more objects and companions.

Mass function is bimodal with ejected low-mass objects and accreted high-mass objects.

Low turbulence can still produce multiple systems.

Abstract

(Abridged) We explore, by means of a large ensemble of SPH simulations, how the level of turbulence affects the collapse and fragmentation of a star-forming core. All our simulated cores have the same, except that we vary (a) the initial level of turbulence (as measured by the ratio of turbulent to gravitational energy, $\alpha_{\rm turb} \equiv U_{\rm turb}/|\Omega| = 0, 0.01, 0.025, 0.05, 0.10 {\rm and} 0.25$) and (b), for fixed $\alpha_{\rm turb}$, the details of the initial turbulent velocity field (so as to obtain good statistics). A low level of turbulence ($\alpha_{\rm turb} \sim 0.05$) suffices to produce multiple systems. As $\alpha_{\rm turb}$ is increased, the number of objects formed and the companion frequency both increase. The mass function is bimodal, with a flat low-mass segment representing single objects ejected from the core before they can accrete much, and a Gaussian high-mass segment representing objects which because they remain in the core grow by accretion and tend to pair up in multiple systems.