GJ 1132 b receives intense XUV radiation, likely losing its atmosphere

Star system: Gliese 1132 | Distance from the Sun: 41.1 light years

GJ 1132 b is an Earth-sized planet orbiting a small red dwarf star every 1.6 days. Scientists studied how much high-energy XUV radiation the planet has received over its lifetime, which is important for understanding whether it can keep an atmosphere. By analyzing the star's activity and flare history, they found that GJ 1132 b has likely received at least 50 times more XUV radiation than Earth does today.

The study compared different models for how the star's XUV output changes over time and found that an empirical model for red dwarfs predicts more XUV radiation than models based on Sun-like stars. Flares contribute about 20% of the total XUV flux, but the planet's close orbit means it is exposed to intense radiation even without frequent flares. The results suggest that GJ 1132 b is very likely to have lost any atmosphere it once had, placing it on the atmosphere-free side of the so-called cosmic shoreline.

These findings help explain why some close-in planets around red dwarfs are bare and highlight the importance of stellar radiation in shaping planetary atmospheres.

Key findings
- GJ 1132 b has received at least 50 times more XUV radiation than Earth
- The planet is likely atmosphere-free due to intense radiation
- Flares contribute about 20% of the total XUV flux
- Empirical models for red dwarfs predict more XUV than solar-based models
- Stellar radiation is crucial for understanding exoplanet atmospheres

Scientific study

The Range of Cumulative XUV Flux on GJ 1132 b (external link)