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arXiv · 2603.26120

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

Chul-Hwan Kim·Jeong-Eun Lee·Doug Johnstone·Gregory J. Herczeg·Chin-Fei Lee·Logan Francis·Patrick D. Sheehan
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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 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.

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Chul-Hwan Kim, Jeong-Eun Lee, Doug Johnstone, Gregory J. Herczeg, Chin-Fei Lee, Logan Francis, Patrick D. Sheehan. 2026-03-27. Direct evidence for magnetohydrodynamic disk winds driving rotating outflows in protostar HOPS 358. https://arxiv.org/abs/2603.26120

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