Tiny particles of stardust have been found in meteorites. Whether some of these particles, known as ‘pre-solar grains,’ came from classical novae is the focus of ongoing research at Michigan State University (MSU). That research has led to subatomic clues about the origins of these grains.
An artist’s rendering of a classical nova. Image credit: David Hardy, www.astroart.org.
Dr. Christopher Wrede, a physicist at MSU’s National Superconducting Cyclotron Laboratory and the Department of Physics and Astronomy, and his colleagues are investigating whether the pre-solar grains may have formed in a classical nova.
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.
To learn more about this question, Dr. Wrede and co-authors 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.
The findings were published in the March 10-11 issue of the journal Physical Review Letters.
According to the team, silicon-30 is quite rare on Earth; the most common is silicon-28.
Scientists know that silicon-30 is produced in classical novae, but haven’t 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.
“These particular grains are potential messengers from classical novae that allow us to study these events in an unconventional way,” Dr. 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.”
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M. B. Bennett et al. 2016. Isospin Mixing Reveals P30(p,γ)S31 Resonance Influencing Nova Nucleosynthesis. Phys. Rev. Lett. 116, 10-11; doi: 10.1103/PhysRevLett.116.102502
