Thick carbon dioxide atmosphere confirmed for exoplanet 55 Cancri e

Star system: 55 Cancri A | Distance from the Sun: 41.1 light years

The exoplanet 55 Cancri e is a hot, rocky world with a complex atmosphere that has been the subject of recent study. New research using advanced three-dimensional climate models shows that the planet likely possesses a thick, carbon dioxide-rich atmosphere. This conclusion relies on simulations that account for heat distribution across the planet, providing a more detailed look than previous one-dimensional models allowed.

The findings indicate that 55 Cancri e requires an atmosphere with a pressure of at least 10 bar, which is ten times the atmospheric pressure at sea level on Earth, and a carbon dioxide content greater than 1 percent. These results suggest the planet formed with a higher concentration of volatile substances—gases that easily evaporate—than either Earth or Venus.

Researchers utilized complex general circulation models, which are digital tools used to simulate weather and climate patterns on a global scale, to test different atmospheric compositions against telescope data. By matching these simulations to infrared spectra captured by the James Webb Space Telescope, they effectively ruled out the possibility of a thin, carbon dioxide-poor atmosphere.

The study also examined why the planet’s brightness appears to change over time. It concluded that large-scale weather patterns alone cannot explain these variations. Because the atmosphere is thick, sudden releases of gas from the planet's surface are unlikely to cause these changes, pointing toward other potential factors, such as the presence of clouds.

Key findings
- 55 Cancri e possesses a thick atmosphere with pressure exceeding 10 bar.
- The atmosphere contains a significant concentration of carbon dioxide.
- High levels of volatiles suggest the planet had a unique formation history compared to Earth and Venus.
- Standard atmospheric weather patterns are insufficient to explain observed brightness changes.
- Thick atmospheric conditions make transient gas release unlikely as a source of variability.

Scientific study

Reinterpreting the JWST Observations of 55 Cancri e with a Non-Grey General Circulation Model (external link)