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

Kim, Chul-Hwan; Lee, Jeong-Eun; Johnstone, Doug; Herczeg, Gregory J; Lee, Chin-Fei; Francis, Logan; Sheehan, Patrick D · Nat Commun · 2026

basic_science · Level V

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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 H<sub>2</sub>CO, SO, and CH<sub>3</sub>OH 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.