# Using planet migration and dust drift to weigh protoplanetary discs

**Authors:** Yinhao Wu, Clément Baruteau, Sergei Nayakshin  
**arXiv:** [2305.01493](https://arxiv.org/abs/2305.01493)  
**Date:** 2023-05-02  
**Summary page:** https://www.summarizepaper.com/en/paper/2305.01493v1/

## Key points

- Yinhao Wu, Clément Baruteau, and Sergei Nayakshin conducted a study on accurately weighing protoplanetary discs using planet migration and dust drift.
- Data from the Atacama Large Millimeter/submillimeter Array (ALMA) was used to identify over 200 annular structures in protoplanetary discs that suggest the presence of planets.
- Determining the mass of these putative planets is difficult due to degeneracies in disc physical properties.
- The researchers argue against assuming a steady-state model and demonstrate how planet and dust dynamics can lift degeneracies in such models.
- Gas and dust hydrodynamical simulations post-processed with dust radiative transfer calculations were run to determine steady-state disc and planet parameters that reproduced ALMA continuum observations fairly well.
- Allowing for planet migration in the simulation led to opposing constraints of planet migration and dust drift, requiring a maximum disc mass estimate of 0.025 solar masses - much less massive than previously estimated - and for porous rather than compact dust.
- The authors propose extending similar analyses to other sources with suspected planetary companions to refine our understanding of protoplanetary discs' physical properties accurately.

## Summary

The study by Yinhao Wu, Clément Baruteau, and Sergei Nayakshin explores the use of planet migration and dust drift to accurately weigh protoplanetary discs. The researchers utilized data from the Atacama Large Millimeter/submillimeter Array (ALMA) to spatially resolve over 200 annular structures in protoplanetary discs, many of which suggest the presence of planets. However, determining the mass of these putative planets is difficult due to degeneracies in disc physical properties. To address this issue, the researchers argue against assuming a steady-state model where the planet position is fixed and there is a constant source of dust at the outer edge of the disc. Instead, they demonstrate how planet and dust dynamics can lift degeneracies in such models. Using main disc parameters from HD 163296 with a suspected planet at approximately 86 au as an example, they ran gas and dust hydrodynamical simulations post-processed with dust radiative transfer calculations. They first found steady-state disc and planet parameters that reproduced ALMA continuum observations fairly well. However, when allowing for planet migration in the simulation with the same disc mass, they found that the planet underwent runaway migration and reached the inner disc in approximately 0.2 Myr. Further analysis showed that decreasing the disc mass slowed down planet migration but also increased radial drift of dust particles, leading to faster depletion of disc dust. The opposing constraints of planet migration and dust drift required a maximum disc mass estimate of 0.025 solar masses - much less massive than previously estimated - and for porous rather than compact dust. The authors propose extending similar analyses to other sources with suspected planetary companions to refine our understanding of protoplanetary discs' physical properties accurately. Overall, their findings highlight how considering dynamic processes such as planet migration and dust drift can improve our ability to weigh protoplanetary discs accurately - an essential step towards understanding planetary formation and evolution.