First detection of gases in atmosphere of a super-Earth
Super-Earths are thought to be the most common planetary type in our galaxy and are so-called because they have a mass larger than Earth but are still much smaller than the gas giants in the Solar System. The Wide Field Camera 3 (WFC3) on Hubble has already been used to probe the atmosphere of two super-Earths, but no spectral features were found in these previous studies.
Observations were made by scanning WFC3 very quickly across the star to create a number of spectra. By combining these observations and processing through computer analytic 'pipeline' software, the researchers were able to retrieve the spectral fingerprints of 55 Cancri e embedded in the starlight.
"This result gives a first insight into the atmosphere of a super-Earth. 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," said Professor Giovanna Tinetti, also from UCL.
Intriguingly, the data also hinted at a signature for 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, KU Leuven, Belgium, who developed an atmospheric chemical model of 55 Cancri e that supported the analysis of the observations.
"If the presence of hydrogen cyanide and other molecules is confirmed in a few years time by the next generation of infrared telescopes, it would support the theory that this planet is indeed carbon rich and a very exotic place," said Professor Jonathan Tennyson, UCL. "Although, hydrogen cyanide or prussic acid is highly poisonous, so it is perhaps not a planet I would like to live on!"
Source: Europlanet Media Centre [February 16, 2016]