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'Super-Earth' Atmosphere Detected

An artist’s impression of 55 Cancri e (credit: NASA/ESA Hubble Space Telescope)

Astronomers say they have detected remnants of an atmosphere on an exoplanet.

Writing in the Astrophysical Journal, researchers say 55 Cancri e, which is about 40 light years away from Earth, has a “significant amount of hydrogen and helium” left over from when the planet formed.

“This is a very exciting result because it’s the first time that we have been able to find the spectral fingerprints that show the gases present in the atmosphere of a super-Earth,” said Angelos Tsiaras, a University College London PhD student who helped develop the analysis technique.

55 Cancri e is a so-called super-Earth because it is about eight times the mass of our planet. but not as large as gas giants like Jupiter and Saturn. 55 Cancri e has also been called the “diamond planet” because the interior is thought to be rich in carbon.

A year on the planet lasts only 18 hours and temperatures are thought to be as high as 2,000 degrees Celsius.

The astronomers were able to analyze the planet’s atmosphere using the Wide Field Camera 3, or WFC3, on the Hubble Space Telescope and feeding the data into a computer to reveal “spectral fingerprints” about the contents of the atmosphere.

“This result gives a first insight into the atmosphere of a super-Earth,” said UCL professor Giovanna Tinetti. “We now have clues as to what the planet is currently like, how it might have formed and evolved, and this has important implications for 55 Cancri e and other super-Earths.”

In addition to hydrogen and helium, the astronomers say they found the signature of hydrogen cyanide, which indicates a carbon-rich atmosphere.