Researchers from Arizona State University and the University of Chicago have found that carbon-rich planets outside our solar system may be made up of diamonds and silica.
Stars and planets are created when clouds of dust and gas bind together. The ratio of their combined elements influences what kind of stars and planet ultimately form. Stars with lower carbon-to-oxygen ratios tend to have planets similar to Earth, mainly comprised of silicates and oxides with few diamonds. Meanwhile, those with higher ratios of carbon to oxygen, given that there is water, end up with carbon-rich planets.
To understand how these carbon-rich planets behave, the researchers conducted an experiment to recreate the environment inside them. For it, they used two high-pressure diamond anvil- high-quality diamonds shaped like anvils. They then submerged silicon carbide in water and compressed it between the two anvils at very high pressure.
To monitor how the silicon carbide reacted with the water, they then heated the sample with lasers, taking X-ray measurements as it got hotter.
As they predicted, thanks to the high heat and pressure, the silicon carbide reacted with the water to produce diamonds and silica. These findings build upon previous investigations in which NASA took a closer look at exoplanet 55 Cancri e, after research suggested it may be rich in carbon.
While an interesting prospect to consider- especially for diamond enthusiasts- the researchers say that these carbon-rich planets are likely uninhabitable. They said, "While Earth is geologically active (an indicator of habitability), the results of this study show that carbon-rich planets are too hard to be geologically active, and this lack of geologic activity may make atmospheric composition uninhabitable."
Regardless of whether or not it is possible to live on these planets, however, the researchers say that these findings are nevertheless important in improving our ability to understand and characterize exoplanets.