Presolar Grains

Presolar grains are interstellar solid matters which are in the form of small solid grains that formed even before the formation of the sun. Presolar stardust grains formed in the exit and cooling gases of earlier presolar stars.

Highlights

Within each pre-solar star stellar nucleo-synthesis occurs and it gives each grain a unique isotopic composition. This composition differs from the isotopic composition of our solar system and the galactic average. The presolar origins can be indicated by the isotopic signatures which are often traced in very specific astrophysical nuclear processes which occur within host stars.

Facts about presolar grains

Presolar grains of silicon carbide are the oldest solid materials ever discovered. These grains were formed before the formation of the solar system and are therefore called presolar grains. Presolar grains are extremely rare, only found  in about 5% of meteorites that fall to Earth.

What can presolar grains reveal?

It could reveal the phenomenon of star formation in the Milky Way. Such as the presence of silicon carbide in meteorites that are samples of star dust. These grains can also provide clues regarding the formation of stars in the Milky Way galaxy.

How were these grains studied?

These grains were studied using transmission or scanning of electron microscopy, secondary ion mass spectrometry and mass spectrometry methods. These grains made of diamonds and are several nanometers in size and are therefore called nanodiamonds. Due to their small size, nanodiamonds are difficult to study and, although they were among the first pre-solar grains to be discovered, relatively little is known about them.