Protostellar Outflow Evolution in Turbulent Environments

TL;DR

This study uses numerical simulations to investigate how protostellar outflows interact with turbulent environments, showing that outflows can both be shaped by and sustain turbulence, challenging previous assumptions.

Contribution

The paper demonstrates through simulations that protostellar outflows can re-energize turbulence and influence its structure, providing new insights into star-forming environment dynamics.

Findings

Outflows modify ambient turbulence and jet morphology.

Fossil cavities can re-energize decaying turbulence.

Energy spectra indicate cavity disruption drives turbulence.

Abstract

The link between turbulence in star formatting environments and protostellar jets remains controversial. To explore issues of turbulence and fossil cavities driven by young stellar outflows we present a series of numerical simulations tracking the evolution of transient protostellar jets driven into a turbulent medium. Our simulations show both the effect of turbulence on outflow structures and, conversely, the effect of outflows on the ambient turbulence. We demonstrate how turbulence will lead to strong modifications in jet morphology. More importantly, we demonstrate that individual transient outflows have the capacity to re-energize decaying turbulence. Our simulations support a scenario in which the directed energy/momentum associated with cavities is randomized as the cavities are disrupted by dynamical instabilities seeded by the ambient turbulence. Consideration of the energy power spectra of the simulations reveals that the disruption of the cavities powers an energy cascade consistent with Burgers'-type turbulence and produces a driving scale-length associated with the cavity propagation length. We conclude that fossil cavities interacting either with a turbulent medium or with other cavities have the capacity to sustain or create turbulent flows in star forming environments. In the last section we contrast our work and its conclusions with previous studies which claim that jets can not be the source of turbulence.