Presolar mineral

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Presolar minerals , often presolar grains or stardust called, are tiny crystals that are part of the fine-grained matrix of primitive meteorites are and before ( "pre") the formation of the solar system existed.

Presumably they originated in supernova explosions or in the vicinity of red giant stars . They later became part of the molecular cloud from which the solar nebula ultimately separated and collapsed to form the solar system. The presolar minerals presumably survived the collapse of the solar nebula and the subsequent formation of planetesimals , from which the primitive meteorites originate, because they consist of resistant, refractory minerals.

The following types of presolar crystals have been identified so far:

Noble gases with unusual isotope ratios were found in primitive meteorites as early as the mid-1960s . Even then, this led to the conclusion that it is presolar minerals that act as carriers of these noble gases in these meteorites. But it wasn't until 1987 that tiny diamonds and silicon carbide grains could be identified as carriers. Since solar matter has a fairly homogeneous isotopic composition, the additional isotopic anomalies found in the minerals prove the presolar origin of these extraordinary crystals.

Presolar diamonds are only a few nanometers in size , which is why they are also called nanodiamonds. Although nanodiamonds were the first presolar crystals to be discovered, along with silicon carbide crystals, relatively little is known about them. The remaining presolar crystals have a typical size in the micrometer range and are therefore easier to examine.

Presolar crystals are mainly examined using

Individual evidence

  1. ^ Roy S. Lewis et al .: Interstellar diamonds in meteorites . Nature 326, 1987, 160-162, doi: 10.1038 / 326160a0 ( online as conference abstract ).
  2. ↑ Thomas Bernatowicz et al .: Evidence for interstellar SiC in the Murray carbonaceous meteorite . Nature 330, 1987, pp. 728-730, doi: 10.1038 / 330728a0 .

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