Stardust left behind from the dawn of our solar system has allowed scientists to estimate the Sun took between 10 and 20 million years to form.
While there is consensus the Sun formed about 4.6 billion years ago from a molecular cloud of gas and dust, less was known about how long the formation took.
The findings were and relied on tools pioneered by Monash University astrophysicists led by Associate Professor Amanda Karakas.
Dr Karakas said the tools, called stellar evolution models, allow scientists to calculate how the chemical composition changes when stars age as a result of nuclear reactions.
“From these models, we can determine which elements are produced by stars and how those elements are expelled into the galaxy,” she said.
“These results are crucial for understanding what made up the gas and dust our Sun formed from.
“This is an exciting study because it provides an answer to one of the most enduring questions around the formation of our solar system.”
The new study was led by TRIUMF PhD candidate Guy Leckenby and an international consortium of scientists including former Monash University researcher Dr Maria Lugaro, now based at Konkoly Observatory in Hungary, and University of Szeged and Konkoly Observatory PhD candidate Balazs Szanyi.
The new study was prompted by the successful observation of the rare decay of highly-charged thallium at the GSI Helmholtz Centre, a nuclear research laboratory in Darmstadt, Germany.
Dr Lugaro and Szanyi worked with Dr Karakas on the stellar evolution models, while Szanyi performed the calculations used in this study.
To determine how long it took the Sun to form, the scientists estimated the levels of radioactive forms of lead expected in stars depending on their mass and age.
These calculations were based on the Monash models of ageing red giant stars developed by Dr Karakas and her colleagues, and other recent nuclear physics research
“Ageing red giant stars are the only place in the universe to generate this particular unstable isotope lead, a radioactive form of lead, which gets mixed into giant clouds of gas and dust and starts decaying,” she said.
“Our Sun formed from such a cloud, with some of the first solid fragments trapping some of this lead, which acts like a timestamp to give us clues to the formation time.
Dr Karakas is optimistic about the value her stellar evolution models will provide to astrophysics in the future.
“The nuclear physics data up until now has precluded us from making accurate predictions of production rates of this radioactive form of lead, so this is a huge step forward,” she said.
“These findings strengthen the accuracy of our tool and will be used to date other rock and nuclear samples we find in meteorites.
“It opens the door for additional discoveries to deepen our understanding about the elements that make up our universe, like where our planets came from and how other solar systems formed.”
The study has been published in Nature and is available online:
Artist impression image available.
