There are several giant planets among us, worlds of gas and ice to be more specific. They orbit the same star, but their environmental conditions and chemical composition are very different from those of Earth. These huge planets, Jupiter, Saturn, Neptune and Uranus, can be used as natural laboratories for the physics of matter at extreme temperatures and pressures. And that is what an international team has done, including scientists from the SLAC National Accelerator Laboratory (USA), who have developed a new experimental setup to measure how chemical elements behave and mix inside the giants. ice creams, which could offer information on the formation and evolution of planetary systems.
Neptune and Uranus are certainly two of the least understood planets in our solar system. Aside from being very, very, far away, only a single space probe, Voyager 2, has come in for a flyby, and no dedicated long-term missions have ever been sent. But understanding them better, knowing more about them, is essential to understand the planets of the entire galaxy. Because let’s not forget that planets like Neptune are 10 times more common than those similar to Jupiter, according to NASA.
In 2017, a study confirmed that 200-kilogram diamonds rain on Uranus and Neptune and that this rain occurs about 8,000 kilometers below the surface of both planets .
Experimental evidence
The new hypothesis as to why diamonds may rain deep in the hearts of Neptune and Uranus is based on the fact that the intense heat and pressure thousands of kilometers below the surface of these ice giants should separate the ice giants. composed of hydrocarbons, with the carbon compressing into diamond and sinking even deeper into the planetary cores.
To test this hypothesis, the experts conducted experimental tests using the Linac Coherent Light Source X-ray laser (LCLS) for more precise measurements of how this “diamond shower” process should occur, with a pressure of approximately 1, 5 million atmospheres and a temperature of 4,730 ºC, discovering that carbon becomes a crystalline diamond directly. Laboratory tests showed that at least a quarter of the carbon pools bind. And in those groups, carbon becomes its strongest disposition: diamonds.
“This research provides data on a phenomenon that is very difficult to model computationally: the ‘miscibility’ of two elements, or how they combine when mixed,” explained Mike Dunne, director of LCLS.
“In the case of the ice giants, we now know that carbon almost exclusively forms diamonds when it separates and does not take on a transitional fluid shape,” said Dominik Kraus of Helmholtz-Zentrum Dresden-Rossendorf, co-author of the paper that publishes the journal Nature Communications.
The shower of diamonds on Neptune and Uranus plays quite a role in the internal energy balance of these distant planets. The newly created diamonds would sink, generating heat as they slowly rub against the dense material around them; this would allow the planets to maintain such a warm interior. And it is that the interior of Neptune is much hotter than it should be (it emits 2.6 times more energy than the Sun absorbs) . And now we know why.
This experiment will make it possible to ‘probe’ the interior of other planets in the solar system. Jupiter and Saturn, maybe?
Referencia: S. Frydrych et al. Demonstration of X-ray Thomson scattering as diagnostics for miscibility in warm dense matter, Nature Communications (2020). DOI: 10.1038/s41467-020-16426-y
