Grains of sand from supernova found in meteorites

Washington: Scientists have been studying stars by looking at specks of dust carried to Earth in meteorites. This technique for studying the stars gives scientists information that cannot be obtained by the traditional techniques of astronomy, such as telescope observations or computer modeling.

Now scientists working at Washington University in St. Louis with support from the McDonnell Center for the Space Sciences, have discovered two tiny grains of silica (SiO2; the most common constituent of sand) in primitive meteorites. This discovery is surprising because silica is not one of the minerals expected to condense in stellar atmospheres-in fact, it has been called "a mythical condensate." Five silica grains were found earlier, but, because of their isotopic compositions, they are thought to originate from AGB stars, red giants that puff up to enormous sizes at the end of their lives and are stripped of most of their mass by powerful stellar winds. These two grains are thought to have come instead from a core-collapse supernova, a massive star that exploded at the end of its life. Because the grains, which were found in meteorites from two different bodies of origin, have spookily similar isotopic compositions, the scientists speculate that they may have come from a single supernova, perhaps even the one whose explosion is thought to have triggered the formation of the solar system. The scientists can tell these grains came from ancient stars because they have highly unusual isotopic signatures. (Isotopes are different atoms of the same chemical element that have a slightly different mass.) The findings are published in Astrophysical Journal Letters. ANI