A low-mass supernova — a star exploding at the end of its life-cycle — triggered the formation of our solar system, says a study based on new models an evidence from meteorites. Supernova left forensic evidence in meteorites that formed at the birth of our solar system.
For the study, a research team led by University of Minnesota Professor Yong-Zhong Qian examined telltale patterns of short-lived radionuclides that stellar explosion produced and which are preserved today as isotopic anomalies 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. 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 the solar system.
The collapse formed the proto-Sun with a surrounding disc where the planets were eventually born. But what was not known conclusively was what initiated the event. Scientists had already suspected that a supernova would have enough energy to trigger the disturbance, but there was no conclusive evidence to support this theory.
The researchers realised that previous efforts in studying the formation of the solar system were focused on a high-mass supernova trigger, which would have left behind a set of nuclear fingerprints that are not present in the meteoric record.
Qian and his collaborators decided to test whether a low-mass supernova, about 12 times heavier than our sun, could explain the meteoritic record. They began their research by examining Beryllium-10, a short-lived nucleus that has four protons (hence the fourth element in the periodic table) and six neutrons, weighing 10 mass units. This nucleus is widely distributed in meteorites.
In fact the ubiquity of Beryllium-10 was something of a mystery in and of itself. Using new models of supernovae, Qian and his collaborators showed that Beryllium-10 can be produced by 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, said the study published in the journal Nature Communications. Meteorites 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,” Qian said. “It points to a low-mass supernova as the trigger,” Qian noted.