The Turbulent Origin of Outflow and Spin Misalignment in Multiple Star Systems

TL;DR

This study uses magneto-hydrodynamic simulations to show that turbulence during star formation leads to randomly oriented spins and outflows in binary systems, explaining observed misalignments as a signature of turbulent fragmentation.

Contribution

It demonstrates through simulations that turbulence causes persistent spin and outflow misalignments in binary star formation, linking observations to turbulent fragmentation origins.

Findings

Protostellar pairs form with randomly oriented angular momenta.

Misaligned outflows persist even as binaries migrate closer.

Simulated outflow distributions match observed molecular outflows.

Abstract

The protostellar outflows of wide-separation forming binaries frequently appear misaligned. We use magneto-hydrodynamic simulations to investigate the alignment of protostellar spin and molecular outflows for forming binary pairs. We show that the protostellar pairs, which form from turbulent fragmentation within a single parent core, have randomly oriented angular momenta. Although the pairs migrate to closer separations, their spins remain partially misaligned. We produce $^{12}$CO(2-1) synthetic observations of the simulations and characterize the outflow orientation in the emission maps. The CO-identified outflows exhibit a similar random distribution and are also statistically consistent with the observed distribution of molecular outflows. We conclude that observed misalignment provides a clear signature of binary formation via turbulent fragmentation. The persistence of misaligned outflows and stellar spins following dynamical evolution may provide a signature of binary origins for more evolved multiple star systems.