An illustration of the interior of 55 Cancri e.
Astronomers from Yale University believe planet 55 Cancri e is made largely of diamond.
The planet was first spotted orbiting its star in 2011. But at that time, scientists thought 55 Cancri e had a rocky core surrounded by water in a state where it is both liquid and gas. New observations challenge that assumption.
The planet was first observed transiting its star last year, allowing astronomers to measure its radius for the first time. This new information, combined with the most recent estimate of its mass, allowed [lead researcher] Madhusudhan and colleagues to infer its chemical composition using models of its interior and by computing all possible combinations of elements and compounds that would yield those specific characteristics.
Planet 55 Cancri e is part of a class of planets known as “super-Earths.” It’s about twice as big as our Blue Marble and eight times as massive. It’s also scorching hot with temperatures that can hit 3,900 degrees Fahrenheit.
Because of these conditions researchers now believe planet 55 Cancri e is mostly made of graphite that surrounds a thick layer of diamond, rather than water.
“When you form diamond, it’s only a matter of temperature and pressure, and the temperature is very high on the surface,” French scientist Olivier Mousis tells New Scientists’ Jacob Aron.