# EDEN Survey: Small Transiting Planet Detection Limits and Constraints on the Occurrence Rates for Late M Dwarfs within 15 pc

**Authors:** Jeremy Dietrich, Dániel Apai, Martin Schlecker, Kevin K. Hardegree-Ullman, Benjamin V. Rackham, Nicolas Kurtovic, Karan Molaverdikhani, Paul Gabor, Thomas Henning, Wen-Ping Chen, Luigi Mancini, Alex Bixel, Aidan Gibbs, Richard P. Boyle, Samantha Brown-Sevilla, Remo Burn, Timmy N. Delage, Lizxandra Flores-Rivera, Riccardo Franceschi, Gabriele Pichierri  
**arXiv:** [2302.04138](https://arxiv.org/abs/2302.04138)  
**Date:** 2023-02-08  
**Summary page:** https://www.summarizepaper.com/en/paper/2302.04138v1/

## Key points

- The search for Earth-sized exoplanets that transit nearby late spectral type red dwarfs is a top priority for atmospheric characterization in the coming decade.
- Wide-field transit surveys like Kepler or TESS face challenges in finding these systems, resulting in unexplored transiting planets and poorly constrained occurrence rates of short-period Earth-sized planets around late M dwarfs.
- The EDEN survey conducted the deepest photometric monitoring campaign of 22 nearby late M dwarf stars using data from over 500 nights on seven 1-2 meter class telescopes.
- The survey successfully identified most (>80%) transiting short-period (0.5-1 d) super-Earths (R > 1.9 R_⊕) and was sensitive (~50%) to transiting Earth-sized planets (1.0-1.2 R_⊕) with a near zero false positive rate, demonstrating an efficient survey strategy.
- No transiting planet detections were made, but the survey provided highly sensitive upper limits on their occurrence rates.
- Multiple hypotheses about the occurrence rates of short period planets around late M dwarfs were explored using the dataset obtained by EDEN, including showing that giant planets at short periods (<1 day) are uncommon around target stars.
- The dataset provides some insight into occurrence rates of short period planets around TRAPPIST-1 like stars and can help test planetary formation and system evolution models while guiding future observations of nearby late M dwarfs.

## Summary

The search for Earth-sized exoplanets that transit nearby late spectral type red dwarfs is a top priority for atmospheric characterization in the coming decade. However, these systems are challenging to find via wide-field transit surveys like Kepler or TESS, resulting in unexplored transiting planets and poorly constrained occurrence rates of short-period Earth-sized planets around late M dwarfs. To address this issue, the EDEN survey conducted the deepest photometric monitoring campaign of 22 nearby late M dwarf stars using data from over 500 nights on seven 1-2 meter class telescopes. The survey included all known single quiescent northern late M dwarfs within 15 pc and used transit-injection-and-recovery tests to quantify its completeness. The results show that the EDEN survey successfully identified most (>80%) transiting short-period (0.5-1 d) super-Earths (R > 1.9 R_⊕) and was sensitive (~50%) to transiting Earth-sized planets (1.0-1.2 R_⊕) with a near zero false positive rate, demonstrating an efficient survey strategy. Although no transiting planet detections were made, the survey provided the most sensitive upper limits on transiting planets orbiting target stars. Furthermore, multiple hypotheses about the occurrence rates of short period planets around late M dwarfs were explored using the dataset obtained by EDEN. For example, it was shown that giant planets at short periods (<1 day) are uncommon around target stars. The dataset also provides some insight into occurrence rates of short period planets around TRAPPIST-1 like stars and can help test planetary formation and system evolution models while guiding future observations of nearby late M dwarfs. In summary, the EDEN survey has significantly advanced our understanding of short period Earth sized exoplanets orbiting nearby late M dwarf stars by providing highly sensitive upper limits on their occurrence rates. This study highlights the importance of conducting deep photometric monitoring campaigns to identify transiting planets and improve our understanding of planetary systems around late M dwarfs.