The planet 55 Cancri e might contain a diamond three times the size of the Earth

Artist's concept of the planet 55 Cancri e behind the Earth (Image NASA)
Artist’s concept of the planet 55 Cancri e behind the Earth (Image NASA)

The planet 55 Cancri e has been known since 2004 and last year the Spitzer Space Telescope was able to observe it directly. This super-Earth, about 40 light years away from our solar system, is so close to its star that its surface temperature is sufficient to melt metals. Astronomers, however, thought that on the surface there was also a lot of water at a supercritical state which therefore behaved in a manner more similar to a liquid than to a gas. Now, however, Yale University researcher Nikku Madhusudhan has a different and even more exotic theory.

The idea of the abundance of water on the planet 55 Cancri e was based on the assumption that its chemical makeup is similar to the Earth’s. Nikku Madhusudhan argues that there might be no water and that instead the main elements that compose it are carbon, iron and silicon. The most important part is that according to this new theory carbon is present in the form of graphite and diamond estimating that the equivalent of about three Earth masses could be in the form of diamond.

Last year, Nikku Madhusudhan led the discovery of a carbon-rich atmosphere in a gas giant exoplanet, the first with these features. The possibility that there were carbon-rich planets also led to the idea that rocky planets could have that kind of chemical makeup as well. This new theory on the planet 55 Cancri e derives from it, supported by the fact that its star is much more carbon-rich than the Sun.

Nikku Madhusudhan and his colleagues used computer models to understand the possible characteristics of 55 Cancri e. Temperature and pressure existing on the surface of the planet might be responsible for the existence of a surface layer of graphite and below it there might be a layer of diamonds so thick as to create such a huge mass.

David Spergel, a professor of astronomy, chair of astrophysical sciences at Princeton University and co-author of the new study, pointed out that planets are much more complex than stars. The consequence is that their chemical makeup may affect their evolution from the thermal and plate tectonic point of view, meaning the seismic, volcanic phenomena and mountain formation.

David Spergel also pointed out that probably 55 Cancri e is just one example of the different chemical makeups that can be found in planets. Whereas the existence of planets seems to be very common, this type of research is just beginning but it’s a step forward in understanding the diversity that we can find when the instruments available to scientists enable them to get more information obout them.

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