Astronomers using JWST report that a hellish super-Earth called 55 Cancrie might have a thick atmosphere made up of either of carbon dioxide or carbon monoxide. If confirmed, it would be the first known rocky planet beyond the Solar System to have a dense atmosphere.
Earth is a rocky planet and its atmosphere is vital in allowing life to flourish, protecting it from the Sun's radiation and the harshness of space. Mars is also a rocky planet, however, its very thin atmosphere, just 1 percent of Earth's, may be part of the reason there is (as far as we know) no life on the Red Planet. An atmosphere isn't necessarily an indicator of a potentially habitable planet but it's a good place to start and though it's unlikely life exists on 55 Cancri e since its surface is a molten ocean of magma, the fact JWST can and has detected hints of a possible atmosphere there is a very promising sign in our ability to hunt for Earth-Like planets.
55 Cancri e has almost twice the radius of our own world and a mass 8.8 times Earth's own. It orbits a star smaller than our Sun but so closely that it goes around it in less than 18 hours, meaning the star-facing side has temperatures high enough to melt iron and the world is expected to be marked by volcanos and a magma ocean. It is that geological activity that might sustain the atmosphere that a team of astronomers believe they have observed.
“The planet is so hot that some of the molten rock should evaporate,” lead author Renyu Hu from NASA’s Jet Propulsion Laboratory, said in a statement seen by IFLScience.
55 Cancri e is tidally locked so its night side is in constant darkness and its day side constantly facing the scorching star. If the planet was without an atmosphere, the day side would be very hot and the night side very cool, but this is not what JWST found. The day side is cooler than expected and while lava flow to the night side can explain some of it, an atmosphere can better explain the cooling observed.
“This is a very strong indication that energy is being distributed from the dayside to the nightside, most likely by a volatile-rich atmosphere,” Hu explained.
However, more observations are needed to truly characterize what is going on around 55 Cancri e; the evidence is compelling but to solve such a conundrum as this planet, astronomers need more information.
“55 Cancri e is one of the most enigmatic exoplanets. Despite enormous amounts of observing time obtained with a dozen of ground and space facilities in the past decade, its very nature has remained elusive, until today, when parts of the puzzle could finally be put together thanks to the JWST,” explained co-author Professor Brice-Olivier Demory from the University of Bern.
JWST's ability to pick up this potential atmosphere bodes well for its ability to detect cooler, more likely candidates for potentially habitable planets. It should also lead to a better understanding of planets as a whole. “JWST is really pushing the frontiers of exoplanet characterization to rocky exoplanets,” Hu said. “It is truly enabling a new type of science,” said Hu.
The study is published in the journal Nature.
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