Laboratory formation of a scaled protostellar jet by coaligned poloidal magnetic field

TLDR

Bipolar jets are observed in many astrophysical systems, but their formation and morphology beyond launch remain poorly understood. The study uses scaled laboratory experiments to test whether a poloidal magnetic field can produce stable, narrow collimation of protostellar jets. The laboratory plasma becomes focused with an interior cavity, producing a standing conical shock from which the jet emerges; simulations suggest this mechanism explains X‑ray emission features seen at the base of protostellar jets such as HH 154.

Abstract

Although bipolar jets are seen emerging from a wide variety of astrophysical systems, the issue of their formation and morphology beyond their launching is still under study. Our scaled laboratory experiments, representative of young stellar object outflows, reveal that stable and narrow collimation of the entire flow can result from the presence of a poloidal magnetic field whose strength is consistent with observations. The laboratory plasma becomes focused with an interior cavity. This gives rise to a standing conical shock from which the jet emerges. Following simulations of the process at the full astrophysical scale, we conclude that it can also explain recently discovered x-ray emission features observed in low-density regions at the base of protostellar jets, such as the well-studied jet HH 154.