Accounting for the diversity in stellar environments

TL;DR

This study uses high-resolution magnetohydrodynamic simulations to explore how diverse stellar environments influence star and disk formation, revealing significant variability driven by magnetic fields and turbulence.

Contribution

It provides the first detailed simulation-based analysis of how environmental factors affect accretion and disk formation around solar-mass stars.

Findings

Accretion rates peak early and decline over time.

Material infall occurs mainly through filaments and sheets.

Disk formation varies greatly due to magnetic and turbulent effects.

Abstract

Stars and their corresponding protoplanetary disks form in diverse environments. To account for these natural variations, we investigate the formation process around nine solar mass stars with a maximum resolution of 2 AU in a Giant Molecular Cloud of (40 pc)$^3$ in volume by using the adaptive mesh refinement code \ramses. The magnetohydrodynamic simulations reveal that the accretion process is heterogeneous in time, in space, and among protostars of otherwise similar mass. During the first roughly 100 kyr of a protostar evolving to about a solar mass, the accretion rates peak around $10^{-5}$ to $10^{-4}$ M$_{\odot}$ yr$^{-1}$ shortly after its birth, declining with time after that. The different environments also affect the spatial accretion, and infall of material to the star-disk system is mostly through filaments and sheets. Furthermore, the formation and evolution of disks varies significantly from star to star. We interpret the variety in disk formation as a consequence of the differences in the combined effects of magnetic fields and turbulence that may cause differences in the efficiency of magnetic braking, as well as differences in the strength and distribution of specific angular momentum.