Some carbon-rich exoplanets, scattered throughout the Solar System, can be made of diamond and silica, given the right circumstances of temperature and pressure. This is suggested by a new study published in The Planetary Science Journal in August, conducted by scientists at Arizona State University and the University of Chicago, both in the United States.
Planets and stars are formed from the same gas cloud, presenting similar compositions. In stars with a lower carbon to oxygen ratio, the formation of Earth-like planets is more likely, that is, composed of oxides and silicates, with a low diamond content.
Those who orbit stars with a higher proportion of carbon to oxygen can convert a significant part of their mass into diamond and silicate, if there is contact with water during their formation period, according to the researchers. Based on this last hypothesis, they did an experiment, simulating the interior of a carbon-rich exoplanet.
To do so, they dipped silicon carbide in water and compressed it between diamond anvils, at very high pressure levels, heating the mass with laser and making measurements with X-ray machines. As expected, the result of the experiment showed a reaction between silicon carbide and water, transforming the mixture into silica and diamonds.
If diamond planets do exist, they probably shouldn’t harbor life. That’s because carbon-rich celestial bodies are rarely geologically active, making life as we know it unfeasible, according to study participants.
“Regardless of habitability, this is an additional step to help us understand and characterize the ever-expanding and enhanced observations of exoplanets,” explained Arizona State University geophysicist Harrison Allen-Sutter, one of the study’s co-authors.