Science & Technology, UK (Commonwealth Union) – An astonishing finding has been made by researchers hailing from the University of Sheffield and Imperial College London. They have observed a ‘retired’ Asymptotic Giant Branch (AGB) star traversing through a youthful star-forming region, overturning previous assumptions.
The enigmatic Asymptotic Giant Branch (AGB) stars shine with a unique radiance, has provided a glimpse into the intricate dance of cosmic evolution. These colossal stars, often referred to as “retired” giants, have captivated the attention of astronomers and researchers, illuminating our understanding of stellar life cycles and the origins of essential elements in the universe.
The journey of a star is a cosmic ballet choreographed by the forces of gravity, nuclear fusion, and radiation. AGB stars mark a critical phase in this grand performance, emerging from the cores of intermediate-mass stars as they near the twilight of their existence. As these stars exhaust their nuclear fuel, their cores contract while the outer layers swell dramatically, transforming them into bloated giants.
During this phase, AGB stars become incredibly luminous, radiating vast amounts of energy into the surrounding space. Their luminosity makes them visible from great distances, contributing to the vibrant tapestry of our night sky.
Utilizing the Gaia satellite, a €740 million endeavor dedicated to mapping the positions of countless stars within our Galaxy, the researchers identified this unique occurrence in a key zone believed to be a birthplace for stars similar to our Sun. The latest Gaia data release, known as Data Release 3, has empowered the research team to precisely locate these intruding stars, referred to as interlopers. These interlopers are stars that were not born within the region but are merely passing through. While the team had previously detected youthful interloping stars, they have now encountered an older, evolved star of the AGB variety journeying through the same region.
Earlier studies have indicated that these retired AGB stars generate significant amounts of radioactively unstable chemical elements, specifically Aluminium-26 and Iron-60. These elements were transported to our nascent Solar System during the period of planet formation and are believed to have played a dominant role in the initial internal warming of Earth.
Intriguingly, Aluminium-26 and Iron-60 might have indirectly contributed to the geological phenomenon of plate tectonics on our planet, a process vital for maintaining a habitable atmosphere on Earth. The research team has meticulously computed the potential amount of Aluminium-26 and Iron-60 from the AGB star that could have been assimilated by a star akin to our Sun during the formation of its planetary system.
Dr Richard Parker, a lecturer in Astrophysics from Department of Physics and Astronomy at the University of Sheffield, who is also the lead author of the study, says “Until now, researchers have been sceptical that these old, evolved stars could ever meet young stars that are forming planets, so this discovery reveals much more about the dynamics, relationships and journeys of stars.”
“By showing that AGB stars can meet young planetary systems, we have shown that other sources of Aluminium-26 and Iron-60, such as the winds and supernovae of very massive stars, may not be required to explain the origin of these chemical elements in our Solar System.”
Dr. Christina Schoettler, an Astrophysics research associate within the Department of Physics at Imperial College London, successfully pinpointed the AGB star while analyzing the Gaia DR3 dataset. According to her, Gaia is leading a paradigm shift in our comprehension of star formation and subsequent Galactic motion. The unanticipated identification of a mature, evolved star situated in close proximity to nascent planet-forming stars serves as a remarkable illustration of the fortuitous nature inherent in scientific exploration.
The forthcoming phase of this study involves an endeavor to uncover additional evolved stars within burgeoning star-forming domains, aiming to gauge the prevalence of these retired interlopers.
