Misaligned Disks in the Binary Protostar IRS 43

TL;DR

High-resolution ALMA observations of IRS 43 reveal multiple, significantly misaligned Keplerian disks around the binary protostar, indicating turbulence likely influenced its formation process.

Contribution

This study provides detailed measurements of disk orientations and binary parameters, highlighting the role of turbulence in protostellar disk misalignment.

Findings

Disks are misaligned by more than 60 degrees in inclination and position angle.

Binary separation is approximately 74 AU with an inclination less than 30 degrees.

Misalignment suggests turbulence influenced the system's formation.

Abstract

Recent high angular resolution ($\sim$0.2") ALMA observations of the 1.1 mm continuum and of HCO+ J=3-2 and HCN J=3-2 gas towards the binary protostar IRS 43 reveal multiple Keplerian disks which are significantly misaligned ($\gt$ 60$^\circ$), both in inclination and position angle and also with respect to the binary orbital plane. Each stellar component has an associated circumstellar disk while the binary is surrounded by a circumbinary disk. Together with archival VLA measurements of the stellar positions over 25 years, and assuming a circular orbit, we use our continuum measurements to determine the binary separation, a = 74 $\pm$ 4 AU, and its inclination, i $\lt$ 30$^\circ$. The misalignment in this system suggests that turbulence has likely played a major role in the formation of IRS 43.