# Dynamical detection of a companion driving a spiral arm in a protoplanetary disk

**Authors:** Chen Xie, Bin B. Ren, Ruobing Dong, Élodie Choquet, Arthur Vigan, Jean-François Gonzalez, Kevin Wagner, Taotao Fang, Maria Giulia Ubeira-Gabellini  
**arXiv:** [2306.09279](https://arxiv.org/abs/2306.09279)  
**Date:** 2023-06-15  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/2306.09279v1/

## Key points

- Protoplanetary disks hosting spiral arm features have been observed through radio and near-infrared observations.
- Companions may excite spiral density waves in these disks via companion-disk interaction, according to numerical simulations.
- Direct observational evidence for spiral-driving companions had posed challenges to current theories until a recent study using the SPHERE facility at the Very Large Telescope provided multi-epoch observations of the binary system HD 100453.
- The study directly confirmed the long-standing theory on the origin of spiral features in protoplanetary disks by recovering the spiral features and robustly removing starlight contamination.
- The results showed that the spiral pattern motion is consistent with the orbital motion of an eccentric companion driving a spiral arm among protoplanetary disks.
- This first observational evidence of a companion driving a spiral arm provides insight into how hidden spiral-arm-driving planets can be searched for beyond existing ground-based high-contrast imagers.
- It establishes a feasible way to search for these planets as their pattern motion is independent of their mass.
- With this new understanding, future studies can continue to explore and refine our knowledge about protoplanetary disk formation and planetary system evolution.

## Summary

The discovery of protoplanetary disks hosting spiral arm features has been observed through radio and near-infrared observations. Numerical simulations have suggested that companions may excite spiral density waves in these disks via companion-disk interaction. However, direct observational evidence for spiral-driving companions had posed challenges to current theories until a recent study using the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) facility at the Very Large Telescope provided multi-epoch observations of the binary system HD 100453. This directly confirmed the long-standing theory on the origin of spiral features in protoplanetary disks by recovering the spiral features and robustly removing starlight contamination. The results showed that the spiral pattern motion is consistent with the orbital motion of an eccentric companion driving a spiral arm among protoplanetary disks. This first observational evidence of a companion driving a spiral arm provides insight into how hidden spiral-arm-driving planets can be searched for beyond existing ground-based high-contrast imagers. Furthermore, it establishes a feasible way to search for these planets as their pattern motion is independent of their mass. With this new understanding, future studies can continue to explore and refine our knowledge about protoplanetary disk formation and planetary system evolution.