What if you could witness a shower of sparkling diamonds falling from the sky? This might sound like a fairy tale, but it could be a reality on many exoplanets in our galaxy, according to new research.
Exoplanets are planets that orbit stars other than our sun. Some of them are similar to Earth, while others are more like gas giants such as Jupiter and Saturn. These gas giants are mostly made of hydrogen and helium, but they also contain traces of carbon compounds, such as methane and ethane.
Scientists have long speculated that under the extreme pressures and temperatures deep inside these planets, these carbon compounds could transform into diamonds, which would then sink towards the core, creating a “rain” of precious stones.
However, the exact conditions for diamond formation were unclear, and previous experiments using shock waves to simulate the planetary interior yielded conflicting results.
Now, a team of researchers led by SLAC National Accelerator Laboratory in California has found a new way to study this phenomenon, using a combination of static and dynamic compression. They squeezed a thin film of polystyrene, a plastic made of carbon and hydrogen, between two diamonds and then heated it with pulses of X-ray light from the European X-ray free-electron laser in Germany.
They discovered that diamonds began to form at temperatures of about 2200°C and pressures around 19 gigapascals, which are much lower than previously thought. These conditions are similar to those in the shallow interiors of Uranus and Neptune, the ice giants of our solar system.
This means that diamond rain could be possible on a larger number of exoplanets than previously estimated. The researchers calculated that more than 1900 of the confirmed exoplanets could have diamond rain, including some that are smaller than Neptune.
The findings, published in Nature Astronomy, have important implications for our understanding of the structure and evolution of these exotic worlds. For instance, diamond rain could provide an internal source of heat and transport carbon deeper into the planet, affecting its composition and properties. It could also influence the generation of the complex magnetic fields of Uranus and Neptune, which are still poorly understood.
The researchers hope to further explore the effects of diamond rain on exoplanets, as well as other types of exotic precipitation, such as silicon rain or iron rain, that could occur on different types of planets.
The next time you look up at the night sky, you might wonder if some of the distant stars are shining with the light of diamond rain.