High-Resolution Near-Infrared Polarimetry and Sub-Millimeter Imaging of FS Tau A: Possible Streamers in Misaligned Circumbinary Disk System

TL;DR

This study combines near-infrared polarimetry and sub-millimeter imaging to reveal streamer-like structures in the FS Tau A binary system, providing insights into disk evolution in young binaries.

Contribution

It presents the first combined high-resolution near-infrared and sub-millimeter observations showing streamer structures in FS Tau A, indicating complex disk dynamics.

Findings

Detection of arm-like structures extending to 240 AU.

Identification of two streamers connecting the circumbinary disk and stars.

Velocity measurements supporting streamer interpretation.

Abstract

We analyzed the young (2.8-Myr-old) binary system FS Tau A using near-infrared (H-band) high-contrast polarimetry data from Subaru/HiCIAO and sub-millimeter CO (J=2-1) line emission data from ALMA. Both the near-infrared and sub-millimeter observations reveal several clear structures extending to $\sim$240 AU from the stars. Based on these observations at different wavelengths, we report the following discoveries. One arm-like structure detected in the near-infrared band initially extends from the south of the binary with a subsequent turn to the northeast, corresponding to two bar-like structures detected in ALMA observations with an LSRK velocity of 1.19-5.64 km/s. Another feature detected in the near-infrared band extends initially from the north of the binary, relating to an arm-like structure detected in ALMA observations with an LSRK velocity of 8.17-16.43 km/s. From their shapes and velocities, we suggest that these structures can mostly be explained by two streamers that connect the outer circumbinary disk and the central binary components. These discoveries will be helpful for understanding the evolution of streamers and circumstellar disks in young binary systems.