Direct evidence for magnetohydrodynamic disk winds driving rotating outflows in protostar HOPS 358

TL;DR

This study provides direct observational evidence that magnetohydrodynamic disk winds are actively removing angular momentum in a protostar, influencing disk evolution and planet formation.

Contribution

First high-resolution ALMA observations of a rotating, nested outflow in a Class 0 protostar confirming magnetically launched disk winds during early star formation.

Findings

Outflow preserves the disk's rotational sense.

Magnetic lever arm estimated at approximately 2.3.

Wind-launching region constrained to 10-18 AU.

Abstract

Angular momentum removal is a fundamental requirement for star and planet formation, yet the mechanisms driving this process remain debated. Magnetohydrodynamic disk winds, launched along magnetic field lines from extended disk regions, offer a promising solution, particularly in regions where magnetorotational turbulence is weak. Here we present high-resolution Atacama Large Millimeter/submillimeter Array observations of the Class 0 protostar HOPS 358, revealing a rotating, nested outflow structure traced by H2CO, SO, and CH3OH emission. The outflow preserves the disk's rotational sense and is aligned with the disk axis, providing direct observational evidence for a magnetically launched disk wind. From the measured kinematics, we derive a dimensionless magnetic lever arm of approximately 2.3 and constrain the wind-launching region to radii of 10-18 astronomical units within the planet-forming zone. These results demonstrate that magnetohydrodynamic disk winds operate during the deeply embedded phase, efficiently extracting angular momentum while shaping disk evolution and establishing initial conditions for planet formation.