Multiple Stellar Fly-Bys Sculpting the Circumstellar Architecture in RW Aurigae

TL;DR

This study uses high-resolution ALMA observations and archival photometry to analyze the complex tidal interactions and disk structures in the RW Aurigae binary system, revealing multiple fly-bys and disk misalignments.

Contribution

It provides the first detailed ALMA imaging of multiple tidal streams and circumstellar disks in RW Aurigae, indicating multiple stellar fly-bys and disk truncation.

Findings

Detection of additional tidal streams around RW Aur A.

Disks are tidally truncated with radii of 58 au and 38 au.

Identification of a long-term dimming event since 2017.

Abstract

We present high-resolution ALMA Band 6 and 7 observations of the tidally disrupted protoplanetary disks of the RW Aurigae binary. Our observations reveal the presence of additional tidal streams to the previously observed tidal arm around RW Aur A. The observed configuration of tidal streams surrounding RW Aur A and B is incompatible with a single star--disk tidal encounter, suggesting that the RW Aurigae system has undergone multiple fly-by interactions. We also resolve the circumstellar disks around RW Aur A and B, with CO radii of 58 au and 38 au consistent with tidal truncation, and 2.5 times smaller dust emission radii. The disks appear misaligned by 12$^{\circ}$ or 57$^{\circ}$. Using new photometric observations from the American Association of Variable Star Observers (AAVSO) and All Sky Automated Survey for SuperNovae (ASAS-SN) archives, we have also identified an additional dimming event of the primary that began in late 2017 and is currently ongoing. With over a century of photometric observations, we are beginning to explore the same spatial scales as ALMA.