In short: Mercury is the smallest planet within the photo voltaic system and has at all times been a thriller as a result of its darkish floor and excessive core density. Nonetheless, astronomers have lengthy recognized that its floor comprises vital quantities of graphite, a type of carbon. A brand new reveals {that a} thick diamond layer lies beneath that graphite crust at its core-mantle boundary.
Scientists from China and Belgium not too long ago printed a examine in Nature Communications that proposes the existence of a diamond layer at Mercury’s core-mantle boundary. It suggests this layer is as much as 18 kilometers (11 miles) thick. The discovering represents a major advance in understanding planetary differentiation processes – how planets develop distinct inner layers.
The scientists consider the diamond layer shaped as a result of crystallization of Mercury’s carbon-rich magma ocean. Because the planet cooled, this carbon shaped a graphite crust on the floor. Nonetheless, the examine challenges the belief that graphite was the one secure carbon section throughout this era.
“A few years in the past, I seen that Mercury’s extraordinarily excessive carbon content material may need vital implications,” the examine’s co-author, Dr. Yanhao Lin, from the Middle for Excessive Stress Science and Expertise Superior Analysis in Beijing informed Phys.org. “It made me understand that one thing particular in all probability occurred inside its inside.”
The researchers used high-pressure and temperature experiments mixed with thermodynamic modeling to recreate the situations of Mercury’s inside. They achieved stress ranges as much as 7 Giga Pascals, permitting them to check the equilibrium phases of Mercury’s minerals.
They decided that the presence of sulfur in Mercury’s iron core affected the crystallization technique of the magma ocean. Sulfur lowers the liquidus temperature, facilitating the formation of a diamond layer on the core-mantle boundary. It additionally shaped an iron sulfide layer, influencing the carbon content material throughout planetary differentiation.
The diamond layer’s excessive thermal conductivity impacts Mercury’s thermal dynamics and magnetic area technology. The diamond layer helps switch warmth from the core to the mantle, affecting temperature gradients and convection within the liquid outer core, influencing the magnetic area.
The findings even have implications for understanding different carbon-rich exoplanetary methods and terrestrial planets with related sizes and compositions to Mercury. The processes noticed on Mercury may also happen on different planets, doubtlessly leaving related signatures. The examine concludes that related diamond layers may exist in different terrestrial planets, although the situations have to be precisely proper.
