Wednesday, March 2, 2011

How To Build A Coyote Snare

Pianeta Terra: il cromo mancante è nel nucleo

the beginning of the formation of Earth, some forms Rare chrome separated and disappeared deep into the core of the planet, according to a new study has shown geologists at UC Davis .

The discovery, published online by the journal Science on Feb. 24, "will help scientists understand the early stages of planet formation," said Qing-Zhu Yin, a professor of geology at UC Davis and co-author of the study .

Yin, Moynier and Frederic Edwin Schauble and the Department of Earth and Space Sciences at UCLA have used equipment specialist at UC Davis to make very precise measurements of chromium isotopes in meteorites, compared to rocks from the crust, and simulated the first terrestrial environment with computer simulations.

They studied a class of meteorites called chondrites, which are leftovers from the formation of the solar system over four and a half billion years ago.

The addition of chromium to the surface gloss rust-proof metal, gives the color of the emeralds and rubies. It exists in four stable isotopes (nonradioactive) with atomic mass of 50, 52, 53 and 54.
"It 's known for decades that the isotopes of chromium are relatively underrepresented in the mantle and crust," said Yin. This is because
or were volatile and evaporated into space, or because they were sucked into the deepest core of Earth.

very accurate measure of chromium isotopes in meteorites than in terrestrial rocks and comparing them with theoretical predictions, the researchers were able to show for the first time that the lighter isotopes preferentially enter the nucleus. From this, the team concluded that about 65% of chromium is probably missing in the Earth's core.

addition, the separation must have occurred early in the process of formation of the planet, probably in smaller bodies that assemble with the Earth or when the Earth was still molten, but smaller than at present.
The work was funded by contributions NASA and the National Science Foundation.

Translation by Arthur McPaul

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