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This study uses 3D magnetohydrodynamic simulations to investigate how jets from young stellar objects depend on stellar rotation rate and magnetic field strength. The researchers found that jets are launched from magnetic field lines connecting both the star and disk, forming a "spine-tower" structure where the central jet (spine) is surrounded by a disk wind (tower). The stability of this structure determines whether systems produce symmetric bipolar jets, asymmetric jets, or no detectable jets, and counter-rotating jets can naturally occur even without stellar rotation, challenging conventional interpretations of jet properties.
Why it matters
These findings provide a framework for interpreting diverse observations of young stellar systems and offer new diagnostic tools for measuring stellar properties like rotation rates from jet observations. The work helps explain the wide variety of jet behaviors seen in star-forming regions and may improve our understanding of how stars and planetary systems evolve.
Understand the Science
arXiv:2604.09919v2 Announce Type: replace
Abstract: Observations of Young Stellar Objects (YSOs) systems reveal a wide diversity of jet properties, from well-collimated bipolar jets to uni-polar jets and systems with no detectable jet. Both prograde and counter-rotating jets are reported, raising questions about how jets are launched and how their properties relate to the underlying star-disk system. Using 3D non-ideal MHD simulations, we present a suite of models in which jet properties depend sensitively on stellar rotation and magnetic field strength. In all models, jets are launched from “two-legged” magnetic field lines anchored to both the star and the turbulent, magnetically elevated disk surface, with interactions at the disk surface crucial for mediating the magnetosphere-disk coupling. The axial jet and its surrounding disk wind form a characteristic “spine-tower” structure: the spine is the kinematically-dominated jet along open field lines threading the star, and the tower is the surrounding toroidal-field–dominated disk wind. The stability of this structure depends on the balance between the spine’s stabilizing power and the tower’s destabilizing power; if the tower dominates, the disk wind can choke the jet, producing asymmetric or no jets. This relationship allows an upper limit estimate on the toroidal magnetic field strength in the disk wind-launching region using observed outflow properties. Counter-rotating jets naturally appear in models, particularly with non-rotating stars, showing that the classical rotation-poloidal velocity relation does not reliably indicate the jet-launching radius. Instead, it could be used to trace the stellar rotation rate, offering a potential observational diagnostic of stellar spin.