A team of astrophysicists from the United States determined which geochemical processes occur in the depths of the so-called water supnatural — exoplanets the size of Neptune, having on its surface the oceans. The results show that them is a clear bottom, which is a solid phase intermediate between the water and rocks of the composition. This told the researchers in the Proceedings of the National Academy of Sciences.
Having in its composition the water exoplanets are quite common in the Universe, but their elemental composition and the form in which water is on the planet, may be very different from what we’re used to seeing on Earth. These “water worlds”, according to the calculations, covered with a thick layer of water, from hundreds to thousands of kilometers deep. Therefore, such objects can be seen significant differences in geochemical cycles, the composition and structure of rocks. To understand what geological processes are happening on these mysterious aquatic worlds, American astrophysicists have conducted the first study of chemical reactions and geochemical processes occurring in the water subnetting.
A common hypothesis is that the water and solid minerals located in layers in the internal structure of the planets. Since water is lighter under her layer on water-rich planets must be silicates. However, the extreme pressure and temperature at the boundary between water and mineral layers can significantly change the behavior of these materials. To simulate the high pressure and temperature in the laboratory, the creators of the work conducted experiments using cells with diamond anvils.
In their experiment, the scientists loaded silica in water, and squeezing the sample between the diamonds to create a pressure above 60 GPA and then heated it with laser beams. Laser heating of the scientists repeated at the Argonne national laboratory. To control the reaction between silica and water, they investigated the methods of x-ray diffraction during laser heating under high pressure. As a result, scientists unexpectedly discovered a new solid phase containing silicon, hydrogen and oxygen.
“Initially, it was thought that the layers of water and rocks in water-rich planets were clearly separated from each other, — says one of the researchers, an employee of Arizona state University Carole NISR. But we have discovered a previously unknown reaction between water and silica and found that the solid phase of intermediate composition remains stable. The difference between water and the rock was surprisingly blurry at high pressure and temperature”.
