Thanks to the James Webb Space Telescope, scientists have managed to characterize for the first time the atmosphere of a super-Earth, a rocky planet that orbits about 40 light-years away from us. Here’s what was discovered and why it is a very precious result.
Illustration of 55 Cancri e. Credit: ESA/HUBBLE
For the first time, researchers have discovered aatmosphere around a planet outside of Solar systemone super Earth call Janssen or more formally 55 Cancri e. There is no definitive confirmation yet, however scholars are confident in the data collected thanks to the futuristic device James Webb Space Telescope (JWST), the most powerful and sensitive instrument available for space research. The exoplanet, which orbits 41 light years away from us – more or less the same distance as the famous system TRAPPIST-1 – would be surrounded by an atmosphere dense and volatile composed by carbon dioxide or carbon monoxide, with the possible presence of other elements such as water and sulfur dioxide. This was determined by an international research team led by scientists from the Jet Propulsion Laboratory from the NASAwho collaborated with colleagues from various universities around the world.
The Janssen exoplanet was discovered in 2004 and is among the most studied ever, being the first super Earth identified by scientists, i.e. a rocky planet with a mass between two and ten times that of Earth. In this case it is approximately nine times that of the terraqueous globe. The celestial body orbits a red dwarf called Copernicus (55 Cancri A) and has a radius double that of the Earth. It is so close to its parent star that it takes just 18 hours to complete a full orbit; this means that a year on this alien world lasts less than an Earth day. The extreme proximity entails two consequences: one face is constantly turned towards the star (day side) and another is constantly in the dark, furthermore the temperatures on its surface are extreme, around 2,300 degrees on the illuminated face, sufficient to melt the iron. It is in fact a hellish planet covered in lava, totally inhospitable for life as we know it. But that doesn’t mean it isn’t interesting from a scientific point of view, as demonstrated by the discovery of the atmosphere.
By analyzing the differences between the temperatures of the day and night side and the impact on the brightness of the star Copernicus during eclipses, researchers led by Professor Renyu Hu were able to extrapolate the thermal emission alone – thanks to JWST’s NIRCam and MIRI instruments – of the super Earth, a precious piece of data from which it was possible to determine the presence of atmospheric gases. As indicated, Janssen’s is most likely composed of CO2 or carbon monoxide. The data does not suggest the presence of a primordial atmosphere composed of hydrogen and helium.
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The peculiarity lies in the fact that this dense atmosphere would be supported by the underlying magma ocean, therefore not comparable to that present around the Earth or to the very thin one on Mars. It is closer to that detected around the Medici satellite Io, one of Jupiter’s four main moons (the others are Ganymede, Callisto and Europa). Being able to characterize the atmosphere of a rocky planet is crucial because in the future it could help us identify habitable alien worlds. The details of the research “A secondary atmosphere on the rocky Exoplanet 55 Cancri e” were published in the prestigious scientific journal Nature.
