Carbon-rich planets with black graphite surfaces hiding rich seams of聽diamonds may orbit distant stars. Now, researchers have made tiny versions of these weird worlds in the lab to figure out what they are like.
Kaustubh Hakim at the University of Amsterdam in the Netherlands and his colleagues started with three different powdered mixtures of eight聽elements commonly found in young planets, including carbon, iron聽and silicon.
The team placed the mixtures in a cylindrical container and compressed them to pressures up to 2 gigapascals and temperatures up to 1550掳C聽鈥� comparable to the conditions at the centre of a Pluto-sized world.
Advertisement
Mini planets
They took a cross-section of the final products and found that, just like聽in real planets, all the powders had formed separate iron-rich and silicate-rich layers.
鈥淓xperimental studies give us a ground truth on what really could be聽happening in these planets,鈥� says聽Cayman Unterborn at Arizona State University.
For the carbon-rich mixes, the researchers found three main layers: an iron-rich core, a silicate mantle and a top layer of pitch-black graphite. That top layer could significantly change the density of such worlds, making them easier to distinguish from other kinds of planets.
鈥淚f you think about pencil lead, it鈥檚 light, fluffy stuff. A layer of graphite can make a big fluffy planet, and that鈥檚 detectable,鈥� says Marc Kuchner at NASA鈥檚 Goddard Space Flight Center in聽Maryland.
If the graphite is thick enough, it could press down on the carbon below and create a layer of diamonds. The diamonds may harm the potential for life on these worlds, says Unterborn. They could shut down convection within the planet, which might slow or prevent a water cycle like the one that sustains life on Earth.
Kuchner says that life may still be possible on a carbon world, despite its lack of many life-sustaining elements when it forms. After all, water and most of the other ingredients for life on Earth are widely believed to have been delivered on comets after the planet was formed.
鈥淚t鈥檇 be like living on top of a pile of coal, but there鈥檚 no reason you couldn鈥檛 do that as long as you had all the other stuff you need,鈥� says Kuchner. 鈥淵ou鈥檇 dig down and say 鈥榃hat are all these black rocks underneath my garden?鈥欌��
Reference:
