For a few billionths of a second, two samples of ferrous alloys felt the crushing pressure in the middle of a huge, rocky planet three times the size of the Earth. But instead of being on one of the 2000 super-earths, scientists have discovered they were circling other stars, it was here on our home planet – and it was thrown forward with a laser blast.
Little is known about what happens in the Earth's core, researchers report in a new study, and even less is known about these rocky super-Earths, which are larger than our planet but smaller than Neptune – a size which can not be found in our solar system. The researchers' work marks a groundbreaking measurement of pressurized material and provides insight into the modeling of the properties of these mysterious worlds.
"We now have a technique that enables us to directly address the extreme pressures of the deep interiors of exoplanets and measure important properties," said Thomas Duffy, a geoscientist at Princeton University and co-author of the new work, in a statement. [No Way Out? Aliens on ̵
The researchers predicted that the cores of the rocky planets are made of iron interspersed with a lighter element such as silicon. So they set out to understand what's going on with this kind of combination deep inside a planet's core, according to the work's lead author, June Wicks, who was also at Princeton at the time of the research. The core is iron alloyed with about 10 percent of a lighter element, and silicon is one. English: www.dlr.de/en/desktopdefault.aspx/t…_read-11114/ Wicks, who is now a researcher at Johns Hopkins University in Maryland, said, "The knowledge of the crystal structure is the most basic information about the material, the the interior of a planet, since all other physical and chemical properties emanate from the crystal structure, "she added.
To measure these crystal structures, the research team blew up a high-power laser that sat between diamond pieces. The laser vaporized the edge of the diamond and turned some of it into plasma in the chamber, pushing it forward, creating extremely high pressure conditions. Immediately, they sent X-rays through the sample to measure their atomic structure-the highest pressure conditions ever recorded by X-ray diffraction, the researchers said. They reached 1,314 gigapascal pressure, which is more than 13 million times the pressure at sea level on Earth or 3.5 times the pressure in the Earth's core.
The researchers found that at the highest pressures the sample was arranged with less silicon atoms in a densely packed, hexagonal crystal structure, while those with more silicon had a cubic structure that formed cubes with an atom in the middle of eight more (called cubic body-centered pack).
They also measured the densities of the samples under different pressure levels and found that the alloys reached 2.5 times their density on the surface of the earth – comparable to the density of gold or platinum. In a core of super-earth, this type of material would result in a larger core with lower pressure than one consisting only of iron.
"A pure iron core is not realistic," Duffy said education will inevitably lead to the inclusion of significant amounts of lighter elements. Our study first considers these more realistic core compounds. "[The Most Intriguing Alien Planet Discoveries of 2017]
Next, the researchers want to test the influence of other light elements such as carbon or sulfur on iron alloys at high temperatures that could form exoplanet cores.
"The method of simultaneous X-ray diffraction and shock experiments is still in its infancy. So it's exciting to have a & # 39; real application & # 39; "For the Earth's Core and Beyond," Kanani Lee, geophysicist at Yale University
Diana Valencia, a planetary scientist at the University of Toronto-Scarborough who focuses on super-earth and mini-Neptune, and not on the Study was involved, said in the statement that the new technique used in the work is a "very significant" contribution in the field of exoplanet research.
"This is a good study because we are not only from low pressures extrapolate and hope for the best, "she said," This actually gives us the best, "these data give us, and that's what better limits our models."
The study's researchers added that their technique was the samples At higher pressures than ever before, researchers will allow peering into the nuclei of potential planets with greater certainty.
"For a geologist, the discovery of so many extrasolar planets has opened the door to a new field of exploration," said Duffy. "We now find that the types of planets that are out there go far beyond the limited examples in our own solar system, and there is a much wider field of pressure, temperature, and composition space that needs to be explored.
"Understanding the internal structure and composition of these large, rocky bodies is necessary to investigate fundamental issues such as the possible existence of plate tectonics, magnetic field generation, their thermal evolution, and even whether they are potentially habitable," he added.