# The dispersal of protoplanetary discs -- III: Influence of stellar mass on disc photoevaporation

**Authors:** Giovanni Picogna, Barbara Ercolano, Catherine C. Espaillat  
**arXiv:** [2110.01250](https://arxiv.org/abs/2110.01250)  
**Date:** 2021-10-04  
**Summary page:** https://www.summarizepaper.com/en/paper/2110.01250v1/

## Key points

- Study of circumstellar discs around young solar-type stars is crucial for understanding thermodynamics and chemistry
- Influence of X-ray irradiation on disc mass-loss rates is a key factor in research
- Relationship between mass-loss rates and X-ray luminosity/spectrum hardness has been observed
- Linear correlation between mass-loss rates and stellar masses (0.1 to 1 Solar mass) adjusting for X-ray luminosity
- Lower disc aspect ratios allow for greater X-ray irradiation reach, leading to linear increase in mass-loss rates even with constant X-ray luminosity
- New analytical relations provided for mass-loss rates and profiles of photoevaporative winds as a function of stellar mass
- Photoevaporative models accurately predict observed trends in inner-disc lifetime relative to stellar mass, steeper increase below 0.3 Solar mass
- X-ray photoevaporation may explain observed disc dispersal processes
- Ongoing debates about primary mechanisms driving disc dispersal, potential evolution of dominant processes over time and at different locations within the disc

## Summary

The study of circumstellar discs around young solar-type stars is crucial for understanding the thermodynamics and chemistry of these systems. A key factor in this research is the influence of X-ray irradiation on disc mass-loss rates. Previous investigations have shown a relationship between mass-loss rates and X-ray luminosity and spectrum hardness. This study delves into how stellar mass impacts disc photoevaporation, specifically focusing on stars with masses ranging from 0.1 to 1 Solar mass - key targets for missions seeking habitable planets. The results reveal a linear correlation between mass-loss rates and stellar masses when adjusting X-ray luminosity accordingly. Interestingly, this linear increase persists even when X-ray luminosity is held constant due to lower disc aspect ratios allowing for greater X-ray irradiation reach. These findings provide new analytical relations for mass-loss rates and profiles of photoevaporative winds as a function of stellar mass, offering valuable insights for disc and planet population synthesis models. Notably, the study's photoevaporative models accurately predict observed trends in inner-disc lifetime relative to stellar mass, with a steeper increase observed for stars below 0.3 Solar mass. This suggests that X-ray photoevaporation serves as a viable explanation for observed disc dispersal processes. Moreover, the research highlights ongoing debates surrounding the primary mechanisms driving disc dispersal, emphasizing the potential evolution of dominant processes over time and at different locations within the disc. While magnetic disc winds are commonly implicated in angular momentum transfer and early-stage mass loss, there is growing recognition of photoevaporative winds potentially assuming greater significance in later stages. Overall, this comprehensive analysis contributes to advancing our understanding of how stellar characteristics influence circumstellar disc dynamics and sheds light on key factors shaping planetary formation within these evolving systems.