Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): Late infall causing disk misalignment and dynamic structures in SU Aur

TL;DR

This study uses high-resolution imaging to reveal that late infall of material causes disk misalignment and complex structures in the young star SU Aur, highlighting ongoing disk evolution during the class II phase.

Contribution

It provides the first detailed observational evidence of late infall causing disk misalignment and dynamic structures in a class II system, using multi-instrument imaging data.

Findings

Detection of dust tails indicating material falling onto the disk

Observation of a misaligned inner disk causing shadow lanes

Evidence of late infall influencing disk evolution in a young star

Abstract

Gas-rich circumstellar disks are the cradles of planet formation. As such, their evolution will strongly influence the resulting planet population. In the ESO DESTINYS large program, we study these disks within the first 10 Myr of their development with near-infrared scattered light imaging. Here we present VLT/SPHERE polarimetric observations of the nearby class II system SU Aur in which we resolve the disk down to scales of ~7 au. In addition to the new SPHERE observations, we utilize VLT/NACO, HST/STIS and ALMA archival data. The new SPHERE data show the disk around SU Aur and extended dust structures in unprecedented detail. We resolve several dust tails connected to the Keplerian disk. By comparison with ALMA data, we show that these dust tails represent material falling onto the disk. The disk itself shows an intricate spiral structure and a shadow lane, cast by an inner, misaligned disk component. Our observations suggest that SU Aur is undergoing late infall of material, which can explain the observed disk structures. SU Aur is the clearest observational example of this mechanism at work and demonstrates that late accretion events can still occur in the class II phase, thereby significantly affecting the evolution of circumstellar disks. Constraining the frequency of such events with additional observations will help determine whether this process is responsible for the spin-orbit misalignment in evolved exoplanet systems.