Presolar Grains – Types and Abundances скачать в хорошем качестве

Presolar Grains – Types and Abundances

Presolar grains originate from other stars, e.g., from red giants, AGB stars, but also from (super)novaes. These grains are then expelled from such stars and added to the ISM. Reprocessing – evaporation & recondensation due to galactic cosmic rays – destroys presolar grains, but about 3% of the ISM survives as original presolar grains (=stardust). These grains can then become part or are being added to protoplanetary disks, where these may end up in meteorites. Presolar grains are sub-µm sized and e.g., SiC, TiC, graphite, nanodiamonds, corundum, etc. – but also silicates. Their abundances are highly variable, but always only in the ppm range.