Takaaki Takeda (VASA Entertainment Co. Ltd.)
The hundreds of gold-rich stars discovered in our Milky Way galaxy may come from smaller galaxies that merged 10 billion years ago, according to new simulations by a supercomputer.
Using the ATERUI II supercomputer at the Center for Computational Astrophysics at the National Astronomical Observatory of Japan, scientists at Tohoku University and the University of Notre Dame developed new simulations of galaxy formation with the highest resolution to date.
The paper was published this week in the Monthly Notices of the Royal Astronomical Society.
The simulation tracked the formation of a virtual Milky Way-like galaxy from the Big Bang to the present day to allow scientists to see how new materials released from old stars are absorbed into new stars.
The elements around us on Earth—from carbon and oxygen to silicon and gold are produced by thermonuclear reactions inside ancient stars. These elements are spread throughout the universe when stars explode.
Distribution of stars and gas in a simulated galaxy. The yellow dots represent the stars and the light blue… [+] dots depict gas.
Yutaka Hirai
“Today’s gold-rich stars tell us the story of our Galaxy,” said Yutaka Hirai of Tohoku University. “These ancient galaxies are the building blocks of the Milky Way. Our findings mean that many of the gold-rich stars we see today are the fossils of the formation of our Galaxy more than 10 billion years ago.”
The simulation, which lasted for several months, allowed scientists to observe the formation of gold-rich stars in our Milky Way for the first time.
It revealed that most of the gold-rich stars formed over 10 billion years ago in small galaxies, which later merged to form the Milky Way. Elements heavier than iron—such as gold and platinum—come from the kind of neutron star mergers (when the cores of two dying stars collide) that are thought to be common in small galaxies.
Although the simulations are just a prediction of what might happen, the predicted abundance of gold-enriched stars in our current Galaxy matches what astronomers can now observe.
This artist’s impression shows two tiny but very dense neutron stars at the point where… [+] they merge and explode as kilonovas.
University of Warwick/Mark Garlick/ESO
Hundreds of gold-rich stars have been identified in the past five years. In May 2022, scientists used the Hubble Space Telescope to discover 65 elements—including gold—in a star called HD 222925, a record for any object beyond our solar system.
Exactly how, why and when evidence is produced is the focus of much advanced research. Last week the European Union announced an award of €11.3 million to the research project HEAVYMETAL (How Neutron Star Mergers Make Heavy Elements), which aims to investigate the composition of chemical elements in neutron star mergers.
When stars about eight times the mass of our Sun run out of fuel, they collapse and disintegrate in supernova explosions, eventually becoming either a neutron star or a black hole.
I wish you clear skies and open eyes.
