NASA’s Spitzer space telescope: Silica (sand) in the supernova remnant Cassiopeia A.

In 2007 NASA’s Spitzer space telescope found the infrared signature of silica (sand) in the supernova remnant Cassiopeia A. 

The light from this exploding star first reached Earth in the 1600s.

The cyan dot just off center is all that remains of the star that exploded. 

Credit: NASA/JPL-Caltech/ O.Krause (Steward Observatory)

It's a bit like learning the secrets of the family that lived in your house in the 1800s by examining dust particles they left behind in cracks in the floorboards.

By looking at specks of dust carried to earth in meteorites, scientists are able to study stars that winked out of existence long before our solar system formed.

This technique for studying the stars – sometimes called astronomy in the lab—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 in the May 1 issue of Astrophysical Journal Letters, 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.

A summary of the paper will also appear in the Editors' Choice compilation in the May 3 issue of Science magazine.

More information: 
AJL paper: iopscience.iop.org/2041-8205/768/1/L17/