Twin Jets and Close Binary Formation

TL;DR

This study uses 3D resistive magnetohydrodynamics simulations to model the formation of close binary systems from prestellar clouds, reproducing observed protobinary features including jets, outflows, and circumstellar disks.

Contribution

First numerical simulation to reproduce all observed characteristics of protobinary systems, including jets, outflows, and disk structures, during early formation stages.

Findings

Protobinary systems form with complex orbital dynamics.

High-velocity jets exceed 100 km/s and are tangled by binary motion.

Circumbinary outflows and circumstellar disks are produced.

Abstract

The formation of a close binary system is investigated using a three-dimensional resistive magnetohydrodynamics simulation. Starting from a prestellar cloud, the cloud evolution is calculated until about 400 yr after protostar formation. Fragmentation occurs in the gravitationally collapsing cloud and two fragments evolve into protostars. The protostars orbit each other and a protobinary system appears. A wide-angle low-velocity outflow emerges from the circumbinary streams that encloses two protostars, while each protostar episodically drives high-velocity jets. Thus, the two high-velocity jets are surrounded by the low-velocity circumbinary outflow. The speed of the jets exceeds $\gtrsim 100 km s^{-1}$. Although the jets have a collimated structure, they are swung back on the small scale and are tangled at the large scale due to the binary orbital motion. A circumstellar disk also appears around each protostar. In the early main accretion phase, the binary orbit is complicated, while the binary separation is within $<30$ au. For the first time, all the characteristics of protobinary systems recently observed with large telescopes are reproduced in a numerical simulation.