A low-mass core-collapse supernova catalyzed the birth of our Solar System, according to a team of scientists led by University of Minnesota researcher.
About 4.6 billion years ago, some event disturbed a cloud of gas and dust, triggering the gravitational collapse that led to the formation of our Solar System.
A core-collapse supernova (CCSN) would have enough energy to compress such a cloud. Yet there was no conclusive evidence to support this theory. In addition, the nature of the triggering supernova remained elusive.
University of Minnesota School of Physics and Astronomy Professor Yong-Zhong Qia and his colleagues from Monash University in Australia, Shanghai Jiao Tong University in China, the University of Minnesota, the University of California and Lawrence Berkeley National Laboratory decided to focus on short-lived nuclei present in the early Solar System.
Due to their short lifetimes, these nuclei could only have come from the triggering supernova. Their abundances in the early Solar System have been inferred from their decay products in meteorites.
As the debris from the formation of the Solar System, meteorites are comparable to the leftover bricks and mortar in a construction site. They tell us what the Solar System is made of and in particular, what short-lived nuclei the triggering supernova provided.
“This is the forensic evidence we need to help us explain how the Solar System was formed. It points to a low-mass supernova as the trigger,” Prof. Qian said.
The team realized that previous efforts in studying the formation of the Solar System were focused on a high-mass CCSN.
They decided to test whether a low-mass CCSN, approximately 12 times heavier than our Sun, could explain the meteoritic record.
They began their research by examining beryllium-10, a short-lived radionuclide widely distributed in meteorites.
In fact, the ubiquity of beryllium-10 was something of a mystery in and of itself. Many researchers had theorized that spallation — a process where high-energy particles strip away protons or neutrons from a nucleus to form new nuclei — by cosmic rays was responsible for the beryllium-10 found in meteorites.
“This hypothesis involves many uncertain inputs and presumes that beryllium-10 cannot be made in supernovae,” Prof. Qian said.
Using new models of supernovae, he and co-authors have shown that beryllium-10 can be produced by neutrino spallation in supernovae of both low and high masses.
However, only a low-mass supernova triggering the formation of the Solar System is consistent with the overall meteoritic record.
“In addition to explaining the abundance of beryllium-10, this low-mass supernova model would also explain the short-lived nuclei calcium-41, palladium-107, and a few others found in meteorites,” Prof. Qian said.
“What it cannot explain must then be attributed to other sources that require detailed study.”
The team’s findings were published online Nov. 22, 2016 in the journal Nature Communications.
Projjwal Banerjee et al. 2016. Evidence from stable isotopes and 10Be for solar system formation triggered by a low-mass supernova. Nature Communications 7, article number: 13639; doi: 10.1038/ncomms13639