Evrim Yazgin
Cosmos science journalist
The Sun took about 10–20 million years to form according to an analysis of stardust left behind from the dawn of our solar system.
Findings published in Nature show how long it took the molecular cloud of gas and dust to come together to create the Sun about 4.6 billion years ago. It is the first time scientists have been able to give a concrete estimate for how long the process took.
Scientists used sophisticated stellar evolution computer models to come up with their estimate.
“From these models, we can determine which elements are produced by stars and how those elements are expelled into the galaxy,” says co-author Amanda Karakas from Melbourne’s Monash University.
“These results are crucial for understanding what made up the gas and dust our Sun formed from,” she adds. “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 estimate for how long it took the Sun was made possible by an experiment in a lab in Germany.
Researchers at the GSI Helmholtz Centre successfully observed the rare decay of highly charged thallium (Tl) into lead (Pb). This allowed the astrophysicists to build a fuller picture of how much radioactive isotopes of lead to be expected in stars of different masses and ages.
Tl-205 requires extreme temperatures of hundreds of millions of degrees Celsius to decay toPb-205.
“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,” Karakas says.
“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.”
“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 adds. “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.”
The research may help to explain how the planets in our solar system formed, as well as how other solar systems developed.
