Evolved Older Stars Passing Through Star-Forming Regions May Have Warmed the Early Earth
Researchers from the University of Sheffield and Imperial College London have discovered “retired” Asymptotic Giant Branch (AGB) stars passing through young star-forming regions.
Using the Gaia satellite, a €740 million mission mapping the locations of billions of stars in the galaxy, the researchers found that the interaction occurred in one of the places where they believe sun-like stars must form.
Gaia’s latest data, Data Release 3, allowed the team to pinpoint the exact star that was interloping. These intervening stars were not formed in the region, but were simply passing through. The team has previously discovered young interstellar stars, but this time they found much older, evolved stars, known as AGBs, passing through the region.
Previous studies have shown that these retired AGB stars produce large amounts of the radioactive unstable chemical elements aluminum-26 and iron-60. Aluminum-26 and iron-60 are thought to have been transported into the solar system during planet formation and to have dominated the early internal heating of the Earth.
Finally, Aluminum 26 and Iron 60 may even indirectly contribute to Earth’s plate tectonics and help maintain a breathable atmosphere on Earth. The team calculated how much Aluminum 26 and Iron 60 is captured from the AGB when a Sun-like star forms a planet.
Dr. Richard Parker, a lecturer in astrophysics in the Department of Physics and Astronomy at the University of Sheffield and lead author of the study published in the Astrophysical Journal Letters, said, “Until now, researchers have been skeptical that such an old, evolved star would ever encounter a young planet-forming star. “Until now, researchers have been skeptical that such an old, evolved star could ever meet a young planet-forming star,” said Dr. Richard Parker, a research associate and coauthor of the study.
By showing that AGB stars can encounter young planetary systems, we have shown that other sources of Al-26 and Fe-60, such as supermassive star winds and supernova explosions, may not be necessary to explain the origin of these chemical elements in the solar system.”
Dr. Christina Shetler, an astrophysics fellow in the Department of Physics at Imperial College London, identified the AGB stars from Gaia DR3 data. Gaia is revolutionizing our ideas about how stars form and then move around the galaxy. The discovery of an old evolved star in close proximity to a young planet-forming star is an excellent example of the power of serendipity in scientific research.”
The next step in this research is to look for other evolved stars in young star-forming regions and establish how common these retired intervening stars are.
Source: Evolved Older Stars Passing Through Star-Forming Regions May Have Warmed the Early Earth
Radio telescope reveals thousands of star-forming galaxies in early Universe