# The vertical structure of debris disks and the impact of gas

**Authors:** Johan Olofsson, Philippe Thébault, Quentin Kral, Amelia Bayo, Anthony Boccaletti, Nicolás Godoy, Thomas Henning, Rob G. van Holstein, Karina Maucó, Julien Milli, Matías Montesinos, Hanno Rein, Antranik A. Sefilian  
**arXiv:** [2202.08313](https://arxiv.org/abs/2202.08313)  
**Date:** 2022-02-16  
**Summary page:** https://www.summarizepaper.com/en/paper/2202.08313v1/

## Key points

- Debris disks provide insights into the evolution and collision rate of planetesimals
- Advancements in contemporary instruments allow for constraining scale height of debris disks at near-infrared or millimeter wavelengths, but usually done for individual targets only
- Authors present geometric modeling of eight edge-on debris disks observed with SPHERE instrument using dual-beam polarimetric imaging mode
- Gas can quickly alter particle dynamics governed by gravity and radiation pressure both in radial and vertical directions
- Particles smaller than a few tens of microns settle efficiently toward the midplane while migrating outward beyond the birth ring when second-generation gas is present
- Scattered light images are better suited for observing vertical settling caused by second-generation gas compared to observations at millimeter wavelengths
- If there is primordial gas, then debris disk will appear very flat both at near-infrared and sub-mm wavelengths
- Far beyond the birth ring, surface brightness profile can be as shallow as $\sim -2.25$
- Study highlights how gas can significantly impact debris disk structure and dynamics which has important implications for understanding planetary system formation and evolution

## Summary

The study of debris disks provides important insights into the dynamical evolution and collision rate of planetesimals. With advancements in contemporary instruments and facilities, it is now possible to constrain the scale height of a few debris disks at near-infrared or millimeter wavelengths. However, this is often done for individual targets only. In this paper, the authors present geometric modeling of eight edge-on debris disks observed with the same instrument (SPHERE) and using dual-beam polarimetric imaging mode. Motivated by the presence of CO gas in two out of the eight disks, the authors investigate the impact that gas can have on the scale height by performing N-body simulations including gas drag and collisions. The results show that gas can quickly alter particle dynamics governed by gravity and radiation pressure both in radial and vertical directions. In particular, particles smaller than a few tens of microns settle efficiently toward the midplane while migrating outward beyond the birth ring when second-generation gas ($M_\mathrm{gas} \leq 0.1$ $M_\oplus$) is present. The authors suggest that scattered light images are better suited for observing vertical settling caused by second-generation gas compared to observations at millimeter wavelengths. However, if there is primordial gas ($M_\mathrm{gas} \geq 1$ $M_\oplus$), then debris disk will appear very flat both at near-infrared and sub-mm wavelengths. Finally, far beyond the birth ring, their results suggest that surface brightness profile can be as shallow as $\sim -2.25$. Overall, this study highlights how gas can significantly impact debris disk structure and dynamics which has important implications for understanding planetary system formation and evolution. This research demonstrates how modern instrumentation allows us to gain new insights into our understanding of planetary system formation through detailed analysis of debris disk structures affected by different types of gases present within them.