Astronomers sample atmosphere on super-Earth for the first time

© ESA/Hubble, M. Kornmesser
Astronomers have for the first time analyzed the gases in the atmosphere of a super-Earth, revealing the presence of hydrogen and helium, but no water vapor. Over eight times the size of Earth, 55 Cancri e is about 40 light years away.

Using new processing techniques on data from the NASA/ESA Hubble Telescope, the University College of London-led team of astronomers have been able to examine the atmosphere of 55 Cancri e, also known as “Janssen,” as it transitioned in front of its parent star. Observations were made by scanning a wide field camera across the star to create a number of spectra which, when combined, gave clues about what the planet was like.

“Our observations of 55 Cancri e’s atmosphere suggest that the planet has managed to cling on to a significant amount of hydrogen and helium from the nebula from which it formed,” said Angelos Tsiaras, a PhD student at UCL who developed the analysis technique along with colleagues at UCL Physics & Astronomy, in a statement.

The atmospheric data gives astronomers clues as to how the super-Earth might have formed and evolved, which will have implications for not only 55 Cancri e, but also other super-Earths. Janssen was one of the first super-Earths to be found by astronomers back in 2004, and it is estimated that the planet and its star were formed about 8 billion years ago. The data also suggested there may be hydrogen cyanide, a marker for carbon-rich atmospheres.

“Such an amount of hydrogen cyanide would indicate an atmosphere with a very high ratio of carbon to oxygen,” said Dr. Olivia Venot of KU Leuven in Belgium in a statement.

Astronomers said that if, in a few years’ time, the presence of hydrogen cyanide and other molecules is confirmed by the next generation of infrared telescopes, “it would support the theory that this planet is indeed carbon rich and a very exotic place.” That has led many astronomers to call the planet the “diamond planet” and speculate that it might have a diamond-like core due to its very high density.

The hydrogen cyanide gases would also make it highly poisonous.

“[It] is perhaps not a planet I would like to live on!” said UCL’s Professor Jonathan Tennyson.

The super-Earth is also super hot, with surface temperatures thought to reach over 3,600 degrees Fahrenheit, or 2,000 degrees Celsius.

The results have been published in the Astrophysical Journal in a study titled, “Detection of an atmosphere around the super-Earth 55 Cancri E.”