Dust grains on Earth may be products of stellar explosions

Microscopic dust particles found in meteoritic material on Earth were likely formed in stellar explosions that occurred long before the creation of the Sun, a new study suggests.
Researchers are working to find whether some of these particles of stardust, known as "pre-solar grains," came from classical nova explosions.
The research has led to tantalising subatomic clues about the origins of these grains, researchers said.
Scientists at the National Superconducting Cyclotron Laboratory at Michigan State University in US are studying whether the particles may have formed in a classical nova, a thermonuclear explosion on the surface of a small star which is part of a binary star system - two stars orbiting each other.

This explosion would have ejected stellar material in the form of gas and dust into the space between stars in the galaxy. Some of that material would have been used in the creation of our solar system.
"When stars die, they spew out material in the form of dust and gas, which then gets recycled into future generations of stars and planets," said said Christopher Wrede, assistant professor of physics at MSU.

The researchers carried out an experiment in which they created and studied the exotic radioactive nuclei that have the greatest influence on the production of silicon isotopes in novae.

It turns out that the grains of stardust contain unusually high amounts of the isotope silicon-30, which is made up of 14 protons and 16 neutrons, researchers said.
Silicon-30 is quite rare on Earth (the most common is silicon-28), they said.
Researchers know that silicon-30 is produced in classical novae, but have not known enough about the nuclear reaction rates in the explosion to be sure how much silicon-30 was created. This has made the origins of the grains uncertain.
The new nuclear reaction path discovered, together with computer models of the explosion, will be used to identify the grains, researchers said.

"These particular grains are potential messengers from classical novae that allow us to study these events in an unconventional way," Wrede said.
"Normally what you would do is point your telescope at a nova and look at the light. But if you can actually hold a piece of the star in your hand and study it in detail, that opens a whole new window on these types of stellar explosions," he said.
The study was published in the journal Physical Review Letters.