In unveiling the nature of the first stars, the main astronomical clue is the elemental compositions of the second generation of stars, observed as extremely metal-poor stars, in the Milky Way. By using machine learning and state-of-the-art supernova nucleosynthesis, Dr. Tilman Hartwig from the University of Tokyo and the Kavli Institute for the Physics and Mathematics of the Universe and colleagues have now found the majority of observed second-generation stars were enriched by multiple supernovae.
Big Bang nucleosynthesis has produced hydrogen, helium, and trace amounts of lithium in the first minutes of the Universe.
All heavier elements were synthesized and released by stars and their violent final fates, such as supernova explosions.
The crucial transition from a primordial Universe to a Universe enriched with heavier elements (summarized as ‘metals’ by astronomers) was initiated by the first stars.
Also termed Population III stars, these stars formed in pristine mini-halos around redshift 6-30.
They ended the cosmic dark ages, they provided the first metals, they contributed to the reionization of the Universe, they might have provided the seeds for the first supermassive black holes, and they have set the scene for all subsequent galaxy formation.
Despite their importance for cosmology and intensive studies in the last decades, only a little is known about the Population III stars.
“Multiplicity of the first stars were only predicted from numerical simulations so far, and there was no way to observationally examine the theoretical prediction until now,” Dr. Hartwig said.
“Our result suggests that most first stars formed in small clusters so that multiple of their supernovae can contribute to the metal enrichment of the early interstellar medium.”
In their study, Dr. Hartwig and co-authors used artificial intelligence to analyze elemental abundances in more than 450 extremely metal-poor stars observed to date.
Based on the newly developed…
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