One-sided Outflows/Jets from Rotating Stars with Complex Magnetic Fields

TL;DR

This study uses axisymmetric MHD simulations to explore how complex magnetic fields in rotating stars lead to asymmetric, one-sided outflows or jets, revealing the influence of magnetic field components on outflow symmetry.

Contribution

It demonstrates that combined dipole and quadrupole magnetic fields in rotating stars can produce persistent or flip-flopping one-sided outflows, a novel insight into stellar jet asymmetry.

Findings

Significant quadrupole component leads to one-sided conical winds.

Without a quadrupole, outflows flip-flop direction every ~30 days.

Pure quadrupole fields produce symmetric outflows.

Abstract

We investigate the generation of intrinsically asymmetric or {\it one-sided} outflows or jets from disk accretion onto rotating stars with complex magnetic fields using axisymmetric (2.5D) magnetohydrodynamic simulations. The intrinsic magnetic field of the star is assumed to consist of a superposition of an aligned dipole and an aligned quadrupole in different proportions. The star is assumed to be rapidly rotating in the sense that the star's magnetosphere is in the propeller regime where strong outflows occur. Our simulations show that for conditions where there is a significant quadrupole component in addition to the dipole component, then a dominantly {\it one-sided} conical wind tends to form on the side of the equatorial plane with the larger value of the intrinsic axial magnetic field at a given distance. For cases where the quadrupole component is absent or very small, we find that dominantly one-sided outflows also form, but the direction of the flow "flip-flops" between upward and downward on a time-scale of $\sim 30$ days for a protostar. The average outflow will thus be symmetrical. In the case of a pure quadrupole field we find symmetric outflows in the upward and downward directions.