Privileged Planet: red giant contributions (Introduction)

by David Turell , Tuesday, December 10, 2019, 18:48 (1811 days ago) @ David Turell

The Earth is far more seeded with elements than planets further out from our sun:

https://phys.org/news/2019-12-stardust-red-giants.html

"Some of the Earth's building material was stardust from red giants, researchers from ETH Zurich have established. They have also explained why the Earth contains more of this stardust than the asteroids or the planet Mars, which are farther from the sun.

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"'The variable proportions of these isotopes act like a fingerprint," Schönbächler says.

"'Stardust has really extreme, unique fingerprints—and because it was spread unevenly through the protoplanetary disc, each planet and each asteroid got its own fingerprint when it was formed."

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"They argue that stardust consisted mainly of material that was produced in red giant stars. These are aging stars that expand because they have exhausted the fuel in their core. Our sun, too, will become a red giant 4 or 5 billion years from now.

"In these stars, heavy elements such as molybdenum and palladium were produced by what is known as the slow neutron capture process. "Palladium is slightly more volatile than the other elements measured. As a result, less of it condensed into dust around these stars, and therefore there is less palladium from stardust in the meteorites we studied," Ek says.

"The ETH researchers also have a plausible explanation for another stardust puzzle: the higher abundance of material from red giants on Earth compared to Mars or Vesta or other asteroids further out in the solar system. This outer region saw an accumulation of material from supernova explosions.

"'When the planets formed, temperatures closer to the sun were very high," Schönbächler explains. This caused unstable grains of dust, for instance, those with an icy crust, to evaporate. The interstellar material contained more of this kind of dust that was destroyed close to the sun, whereas stardust from red giants was less prone to destruction and hence concentrated there. It is conceivable that dust originating in supernova explosions also evaporates more easily, since it is somewhat smaller. "This allows us to explain why the Earth has the largest enrichment of stardust from red giant stars compared to other bodies in the solar system," Schönbächler says."

Comment: Still more evidence on how this planet was carefully prepared for us. Obviously we were the final goal.