# Deprojecting and constraining the vertical thickness of exoKuiper belts

**Authors:** James Terrill, Sebastian Marino, Richard A. Booth, Yinuo Han, Jeff Jennings, Mark C. Wyatt  
**arXiv:** [2306.09715](https://arxiv.org/abs/2306.09715)  
**Date:** 2023-06-16  
**Summary page:** https://www.summarizepaper.com/en/paper/2306.09715v1/

## Key points

- Debris discs are important to understand planetary systems' formation, evolution, and dynamics.
- To fully characterize debris discs, it is necessary to measure their radial and vertical structure.
- Frankenstein is a non-parametric tool that can extract the radial brightness profile of circumstellar discs at any inclination as long as they are optically thin and axisymmetric.
- The authors extended Frankenstein to account for the vertical thickness of an optically thin disc ($H(r)$) and showed how it can be constrained by sampling its posterior probability distribution while fitting the radial profile non-parametrically.
- Using this new method, the authors determined the radial and vertical structure of 16 highly inclined debris discs observed by ALMA.
- They found a wide range of vertical aspect ratios ($h$), ranging from $0.020\pm0.002$ (AU Mic) to $0.20\pm0.03$ (HD 110058), which are consistent with parametric models.
- The authors also found a tentative correlation between $h$ and the disc fractional width, suggesting that wider discs may be more stirred than thinner ones.
- Assuming that debris discs are self-stirred, the thinnest ones would require at least 500 km-sized planetesimals present in them while thicker ones would likely require planets to stir them up.
- The authors also recovered previously inferred and new radial structures including a potential gap in HD 61005's radial distribution.
- Finally, their extension of Frankenstein allows constraining how $h$ varies as a function of radius which they tested on 49 Ceti finding that $h$ is consistent with being constant throughout its radius.
- This study provides new insights into understanding debris discs' vertical thickness and their stirring mechanisms through their radial and vertical structure by using ALMA observations combined with non-parametric tools like Frankenstein which allow extracting information about these structures even when they are highly inclined or have complex features such as gaps or asymmetries in their distributions.

## Summary

This paper focuses on the study of debris discs, which are important to understand the formation, evolution and dynamics of planetary systems. To fully characterize these discs, it is necessary to measure both their radial and vertical structure. However, if a disc is too close to edge-on, deprojecting its emission becomes difficult. In this study, the authors introduce a non-parametric tool called Frankenstein that can extract the radial brightness profile of circumstellar discs at any inclination as long as they are optically thin and axisymmetric. They also extend Frankenstein to account for the vertical thickness of an optically thin disc ($H(r)$) and show how it can be constrained by sampling its posterior probability distribution while fitting the radial profile non-parametrically. Using this new method, the authors determine the radial and vertical structure of 16 highly inclined debris discs observed by ALMA. They find a wide range of vertical aspect ratios ($h$), ranging from $0.020\pm0.002$ (AU Mic) to $0.20\pm0.03$ (HD 110058), which are consistent with parametric models. The authors also find a tentative correlation between $h$ and the disc fractional width, suggesting that wider discs may be more stirred than thinner ones. Assuming that debris discs are self-stirred, the thinnest ones would require at least 500 km-sized planetesimals present in them while thicker ones would likely require planets to stir them up. The authors also recover previously inferred and new radial structures including a potential gap in HD 61005's radial distribution. Finally, their extension of Frankenstein allows constraining how $h$ varies as a function of radius which they test on 49 Ceti finding that $h$ is consistent with being constant throughout its radius. Overall, this study provides new insights into understanding debris discs' vertical thickness and their stirring mechanisms through their radial and vertical structure by using ALMA observations combined with non-parametric tools like Frankenstein which allow extracting information about these structures even when they are highly inclined or have complex features such as gaps or asymmetries in their distributions.