Multiple protostellar outflows from a single protostar with a misaligned disk

TL;DR

This study uses 3D nonideal MHD simulations to explore how misalignment between a protostar's disk and magnetic field leads to multiple outflow components, revealing complex outflow behaviors.

Contribution

It demonstrates that large misalignments can produce secondary spiral outflows alongside classical disk winds, explaining observed multiple outflows in protostellar systems.

Findings

Large misalignment increases the prominence of spiral outflows.

Secondary outflows can dominate over primary disk winds at high misalignments.

Outflow components can coexist and vary over time depending on misalignment angle.

Abstract

We investigate how misalignment between the core angular momentum and the large-scale magnetic field affects protostellar outflows, and whether a single protostellar system can drive multiple outflow components. We perform three-dimensional nonideal magnetohydrodynamic simulations of magnetized rotating cores, focusing on the formation of a protostar, a circumstellar disk, and magnetically driven outflows. The initial angle between the core angular-momentum vector and the magnetic field is systematically varied from $0^\circ$ to $90^\circ$. All models launch a classical magnetocentrifugal disk wind (DW) roughly along the local disk normal. For large misalignment, the system also develops a spiralflow (SF) component that propagates parallel to the disk plane. In a representative model with a $60^\circ$ misalignment, the outflow transitions from a DW-dominated to an SF-dominated phase, with the SF becoming more massive and more extended than the DW, and the two components intermittently coexisting. Across the model suite, the maximum mass and size ratios of SF to DW, as well as the relative lifetimes of the two components, increase for misalignment angles $\gtrsim60^\circ$. We propose that secondary, misaligned outflows (or their fossil remnants) observed in some protostellar systems can be interpreted as the SF component, while the main bipolar outflow traces the DW from the same misaligned system.