Scientists of Bern University (Switzerland) revealed that in antiquity on Mercury there was a rapidly evaporating atmosphere, which was formed from the gas of the magmatic ocean. This is reported in an article published in The Planetary Science Journal magazine.
Planetologists suggest that early Mercury had an ocean of magma, which evaporated, forming an atmosphere from volatile and non-volatile substances. Such oceans are characteristic of stony planets in the early stages of existence, when the bombing of large cosmic bodies, the radioactive decay and the heat of the kernel supported the subsoil and surface in the molten state. The surface temperature at the same time reached 2400 Kelvinov (K), and the magma crystallization occurs at 1400 to.
Researchers simulated four possible composition of the magmatic ocean at two hypothetical sizes of ancient Mercury, while one of the options provides that the radius of the planet was more modern. Volatile substances, such as carbon dioxide, carbon monoxide, molecular hydrogen and water dissolve in magma and may volatile in the form of gas at low pressure. Relatively non-volatile breeding elements: silicon, sodium or iron – can exist in the form of gases (for example, silicon monoxide, SiO), only at very high temperatures.
It is shown that the atmosphere of Mercury evaporated due to several mechanisms. Slipping jeans when light molecules left space with high height and at high speed, played a small role. Sunny wind, photo post and photoionization led to massive losses of the gas shell with a speed of about one or four billion kilograms per second. In this case, the process of evaporation of volatile and non-volatile gases was similar at high temperatures, and the cooling occurred pretty quickly, therefore the main composition of Mercury’s marture at the stage of the magmatic ocean should not have changed significantly. Due to the dissipation of the atmosphere of the planet lost only 0.3 percent of the original mass or a layer of cortex less than 2.3 kilometers thick.
The fact that the modern surface of Mercury is enriched with volatile elements, such as sodium, cannot be explained by the presence of an early atmosphere. According to the conclusions of scientists, the cause could be chemical reactions that occurred in rocks forming due to attracting the substance contained in the outer space.