# A Tail Structure Associated with Protoplanetary Disk around SU Aurigae

## TL;DR

This paper reports ALMA observations revealing a 1000-au tail-like gas structure connected to the SU Aurigae protoplanetary disk, suggesting possible external or internal interactions affecting disk evolution.

## Contribution

First detection of a tail-like gas structure associated with SU Aurigae's disk, providing insights into disk mass transfer and interaction scenarios.

## Key findings

- Discovery of a 1000-au tail-like gas structure
- Physical connection between disk and tail confirmed
- Multiple formation scenarios proposed for the tail

## Abstract

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the CO ($J$=2--1) line emission from the protoplanetary disk around T-Tauri star SU Aurigae (hereafter SU Aur). Previous observations in optical and near infrared wavelengths find a unique structure in SU Aur. One of the highlights of the observational results is that an extended tail-like structure is associated with the disk, indicating mass transfer from or into the disk. Here we report the discovery of the counterpart of the tail-like structure in CO gas extending more than 1000 au long. Based on geometric and kinematic perspectives, both of the disk and the tail-like structure components physically connect to each other. Several theoretical studies predicted the observed tail-like structure via the following possible scenarios, 1) a gaseous stream from the molecular cloud remnant, 2) collision with a (sub)stellar intruder or a gaseous blob from the ambient cloud, and 3) ejection of a planetary or brown dwarf mass object due to gravitational instability via multi-body gravitational interaction. Since the tail-like structures associated with the SU Aur disk is a new example following RW Aurigae, some disks may experience the internal or external interaction and drastically lose mass during disk evolution.