A planet made of diamond

Researchers have discovered that the super-Earth, which is 40 light years away from us, consists mainly of diamond

A new study led by researchers from Yale University suggests that a rocky planet, twice the size of Earth orbiting a star relatively close to our solar system, is made of diamond.

"This is our first glimpse of a rocky world with a completely different chemistry than Earth." says lead researcher Nico Madhusudhan, a postdoctoral fellow in physics and astronomy at Yale. "The surface of these planets will be covered with graphite and diamond rather than water and granite.
The research findings were accepted for publication in the Astrophysical Journal Letters.

The planet, known as 55 Cancri e, has a radius twice that of Earth and a mass eight times greater, which puts it in the category of super-Earths. It is one of five planets orbiting a Sun-like star, 55 Cancri, located 40 light-years from us and visible to the naked eye in the constellation Cancer.

The planet orbits its sun at high speed: its year lasts 18 hours. It is also very hot, and the heat on its surface reaches 2,150 degrees Celsius, so it cannot be settled.

The planet was first observed passing its sun about a year ago, allowing astronomers to measure its radius. The new information, combined with the estimates of its mass, allowed Madhusudhan and his colleagues to estimate its composition, using models of its interior and calculating all the possible combinations of elements and compounds that would give these specific properties.

Astronomers previously thought that the sun of that system had more carbon than oxygen, Madhusudhan and his colleagues confirmed the existence of large amounts of carbonaceous carbon and silicon, and a negligible amount of water that was present when the planet formed.

The astronomers also believed that 55 Cansari contains super-hot water, based on the assessment that its chemical composition is similar to that of the Earth, Madhusudhan says, but the new research suggests that it has no water at all and that it is composed mainly of carbon (in the form of graphite and diamonds), iron, Carbon silicon, and possibly some silicates. The study estimates that at least a third of the planet's mass - or about three Earth masses - may be diamond.

For comparison, the Earth's interior is rich in oxygen but very poor in carbon - less than a thousandth of the mass, says geophysicist Mile Kenani Lee.

The identification of super carbon-rich Earths means that it is no longer possible to associate them with a chemistry similar to that of Earth, Madhusudhan said. The discovery also opens new paths for the study of the geochemical and geophysical processes in Earth-like planets. The carbon-rich composition may affect the planet's thermal evolution and plate tectonics, among other things, with implications for volcanism, seismic activity, and mountain formation.

"Stars are simple, given the mass and age one can know the basic structure and history" says David Spergel, professor of astronomy and holder of the chair of astrophysical sciences at Princeton University, who is not related to the current research. "Planets are much more complex. Diamond-rich super-Earths are just one example of a rich series of discoveries that await us as we begin to explore planets around nearby stars.

In 2011, Madhusudhan led the discovery of a planet with a carbon-rich atmosphere, but at the time it was a giant planet, but the research opened up the possibility of rocky carbon-rich planets (or diamond planets). The new study marks the first time astronomers have identified a diamond planet orbiting a Sun similar to ours and identified its chemical composition. Follow-up observations of the planet's atmosphere and additional assessments of the Sun's composition may strengthen the findings about the planet's chemical composition.

to the notice of the researchers