The Super-Hot Super-Earth

Researchers at NASA using the James Webb Space Telescope analyzed the so-called Super-Hot Super-Earth or “55 Cancri e” and discovered a fascinating discovery. The exoplanet is most likely to be covered by a bubbling ocean of magma and has an atmosphere rich in carbon monoxide and/or carbon dioxide. “Earth has an atmosphere, as do all of the planets in the Solar System. We like to study exoplanets that have an atmosphere to better understand how exoplanets compare to Solar System planets”, explains Diana Dragomir, exoplanet researcher at the University of New Mexico and co-author on the study. “While “55 Cancri e” is larger and also much hotter than Earth, I think it’s a critical stepping stone towards finding and studying the atmospheres of planets more and more like our own”. Dragomir continues:

“55 Cancri e” is 41 light years away from Earth. It is located in the constellation of Cancer. The exoplanet orbits the star Copernicus at a distance of around 1.4 million kilometers, which means that the planet is 65 times closer to its star than the Earth is to the sun. Because it is so close to its host star, it is also much hotter than Earth, with possible temperatures of up to 2,800 degrees Fahrenheit. “55 Cancri e” is twice the size and eight times the mass of Earth. That’s why we call it a super-Earth!”, explains Dragomir. Super-Earths are exoplanets that are larger than Earth but smaller than Neptune. So, although they are large compared to our home, they are quite small compared to other celestial bodies.

Previous research on “55 Cancri e” had pointed to an atmosphere with volatile gases such as oxygen, nitrogen and carbon dioxide. In contrast, the researchers considered the possibility of a lava world enveloped by an atmosphere consisting only of evaporated rock. Using Webb's NIRCam (near-infrared camera) and MIRI (mid-infrared instrument) to measure the infrared light emitted by the planet, the researchers were able to rule out the second possibility and provide the best evidence to date for the presence of atmospheric gases on a rocky exoplanet. “We used spectroscopy obtained with the JWST to study the atmosphere of “55 Cancri e””, says Dragomir. “We found that it contains carbon monoxide and/or carbon dioxide, though there are probably other gases as well. The very detection of these molecules is what tells us that there is an atmosphere on this planet.”

Thus, the exoplanet could be described as rocky however it is more accurate to say that its surface is likely to be molted and shrouded by a magma ocean that outgasses and sustains its complex atmosphere rich in CO2 and/or CO, with the possibility of additional gases such as nitrogen, water vapor, sulfur dioxide, some vaporized rocks and even ephemeral clouds formed by tiny drops of lava condensed in the air.

“I think this intriguing exoplanet will continue to be studied. There is still much we don’t know about it, such as how it came to be so close to its host star, how it is able to have an atmosphere despite the extremely high irradiation it is subjected to, and more specific questions like what kind of volcanic activity exists on its surface” says Dragomir.

This illustration by the Exoplanet Travel Bureau shows futuristic-looking explorers gliding in a protective bubble over the glowing red landscape of the exoplanet "55 Cancri e". Poster: NASA/JPL-Caltech

Ultimately, “55 Cancri e” has also proven to be a worthy exoplanet for sci-fi scenarios, with its bubbling magma ocean resembling the landscape of a futuristic film and reminiscent of the planet Mustafar from Star Wars. “55 Cancri e” is the main protagonist on the poster Lava Life, which shows an explorer gliding over the exoplanet. The poster is part of NASA's Exoplanet Travel Bareau poster series, where scientists, futurists and artists have worked together to imagine futuristic exoplanet travel. All posters in the series are designed in a vintage style and show a different exoplanet as a tourist destination. Unfortunately, it is still not possible to visit the planet as shown.

Nevertheless, there is an alternative: NASA has the Exoplanet Travel Bureau's 360-degree visualization tool on its website. This allows you to marvel at exoplanets as if you were standing on their surface! “55 Cancri e” is also included, so you can explore it from the comfort of your own home.

Original publication:

Hu, R., Bello-Arufe, A., Zhang, M. et al.

A secondary atmosphere on the rocky Exoplanet 55 Cancri e.

Nature, 2024;

DOI: doi.org/10.1038/s41586-024-07432-x