For the first time astronomers have been able to analyze the atmosphere of an exoplanet in the class known as super-Earths, and it’s bone dry.
Using data gathered from the Hubble Space Telescope, and by using new analysis techniques, researchers were able to reveal that exoplanet 55 Cancri e has a dry atmosphere without any indications of water vapor. The results indicate that the atmosphere consists mainly of hydrogen and helium.
The international team, led by scientists from University College London (UCL) in the U.K., took observations of the nearby exoplanet 55 Cancri e. It is located in the planetary system of 55 Cancri, a star that is about 40 light-years from Earth.
The observations were made with the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope.This is a first in detection of gases in the atmosphere of a super-Earth. By exploiting a newly-developed processing technique, the team was able to examine the atmosphere of 55 Cancri e in detail, which revealed the presence of hydrogen and helium, but no water vapor.
Angelos Tsiaras, a PhD student at UCL, who developed the analysis technique along with his colleagues, Ingo Waldmann and Marco Rocchetto, explains:
“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,
“The 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 originally formed.”
According to Space Telescope:
“Super-Earths like 55 Cancri e are thought to be the most common type of planet in our galaxy. They acquired the name ‘super-Earth’ because they have a mass larger than that of the Earth but are still much smaller than the gas giants in the Solar System. The WFC3 instrument on Hubble has already been used to probe the atmospheres of two other super-Earths, but no spectral features were found in those previous studies.
“55 Cancri e, however, is an unusual super-Earth as it orbits very close to its parent star. A year on the exoplanet lasts for only 18 hours, and temperatures on the surface are thought to reach around 2,000 degrees Celsius. Because the exoplanet is orbiting its bright parent star at such a small distance, the team was able to use new analysis techniques to extract information about the planet, during its transits in front of the host star.”
The observations were made by scanning the WFC3 very quickly across the star, which creates a number of spectra. When the researchers combined these observations, and process them through the analytic software, the researchers are able to retrieve the spectrum of 55 Cancri e embedded in the light of its parent star.
Giovanna Tinetti, also from UCL, said:
“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 and how it might have formed and evolved, and this has important implications for 55 Cancri e and other super-Earths.”
Interestingly, however, the data also showed indications of the presence of hydrogen cyanide, which is a marker for carbon-rich atmospheres.
Olivia Venot, KU Leuven, who developed an atmospheric chemical model of 55 Cancri e that supported the analysis of the observations, said:
“Such an amount of hydrogen cyanide would indicate an atmosphere with a very high ratio of carbon to oxygen.”
Jonathan Tennyson from UCL, concludes that:
“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.
“Although hydrogen cyanide, or prussic acid, is highly poisonous, so it is perhaps not a planet I would like to live on!”