# Observability of Debris Discs around M-stars

**Authors:** Patricia Luppe, Alexander V. Krivov, Mark Booth, Jean-François Lestrade  
**arXiv:** [1910.13142](https://arxiv.org/abs/1910.13142)  
**Date:** 2019-10-29  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/1910.13142v2/

## Key points

- Debris discs are second-generation dusty discs formed by collisions of planetesimals
- They have been extensively studied around hot and solar-type stars
- The paucity of debris discs discovered around M-stars remains unclear
- Authors investigate whether the sensitivity and wavelength coverage of present-day telescopes are simply unfavorable for detecting these discs or if they are truly rare
- Using their procedure, authors can reproduce the $2.1^{+4.5}_{-1.7}$% detection rate of M-star debris discs of the DEBRIS survey which implies that these discs can indeed be similar to those around hotter stars but just avoid detection
- Authors apply this procedure to IRAM NIKA-2 and ALMA bands 3, 6 and 7 to predict possible detection rates and give recommendations for future observations
- More sensitive far infrared and single dish sub millimeter telescopes are necessary to discover the missing population of M star debris discs

## Summary

Debris discs, which are second-generation dusty discs formed by collisions of planetesimals, have been extensively studied around hot and solar-type stars. However, the paucity of debris discs discovered around M-stars remains unclear. In this study, authors Patricia Luppe, Alexander V. Krivov, Mark Booth, and Jean-François Lestrade investigate whether the sensitivity and wavelength coverage of present-day telescopes are simply unfavorable for detecting these discs or if they are truly rare. The authors approach this question by examining the Herschel/DEBRIS survey that has searched for debris discs including M-type stars. Assuming that these cool-star discs are "similar" to those of hotter stars in some sense (i.e., in terms of dust location, temperature, fractional luminosity, or mass), they check whether this survey should have found them. Using their procedure, they can reproduce the $2.1^{+4.5}_{-1.7}$% detection rate of M-star debris discs of the DEBRIS survey which implies that these discs can indeed be similar to those around hotter stars but just avoid detection. The authors then apply this procedure to IRAM NIKA-2 and ALMA bands 3, 6 and 7 to predict possible detection rates and give recommendations for future observations. They do not favor observing with IRAM since it leads to lower detection rates than for the DEBRIS survey with only 0.6%-4.5% for a 15 min observation; ALMA observations also do not offer significant improvement with detection rates ranging from 0.9%-7.2%. Therefore more sensitive far infrared and single dish sub millimeter telescopes are necessary to discover the missing population of M star debris discs. Overall this study highlights the need for further investigation into why there is a lack of debris disc discoveries around M stars and suggests that current telescopes may not be sensitive enough to detect them. The authors' findings provide valuable insights for future observations and could potentially lead to the discovery of a new population of debris discs around M stars.