r-Process elements from magnetorotational hypernovae

• Published in: Nature (London) Vol. 595; no. 7866; pp. 223 - 226
• Main Authors: Yong, D., Kobayashi, C., Da Costa, G. S., Bessell, M. S., Chiti, A., Frebel, A., Lind, K., Mackey, A. D., Nordlander, T., Asplund, M., Casey, A. R., Marino, A. F., Murphy, S. J., Schmidt, B. P.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 08-07-2021; Nature Publishing Group
• Subjects: 639/33/34/4120; 639/33/34/4126; 639/33/34/867; Abundance; Astronomical models; Barium; Burning; Carbon; Chemical evolution; Explosions; Galactic evolution; Galaxies; Humanities and Social Sciences; Light elements; Metallicity; Milky Way; multidisciplinary; Nuclear capture; Science; Science (multidisciplinary); Star & galaxy formation; Star formation; Stars; Stars & galaxies; Stellar evolution; Supernovae; Zinc
• ISSN: 0028-0836; 1476-4687; 1476-4687
• DOI: 10.1038/s41586-021-03611-2

Neutron-star mergers were recently confirmed as sites of rapid-neutron-capture (r-process) nucleosynthesis
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. However, in Galactic chemical evolution models, neutron-star mergers alone cannot reproduce the observed element abundance patterns of extremely metal-poor stars, which indicates the existence of other sites of r-process nucleosynthesis
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. These sites may be investigated by studying the element abundance patterns of chemically primitive stars in the halo of the Milky Way, because these objects retain the nucleosynthetic signatures of the earliest generation of stars
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. Here we report the element abundance pattern of the extremely metal-poor star SMSS J200322.54−114203.3. We observe a large enhancement in r-process elements, with very low overall metallicity. The element abundance pattern is well matched by the yields of a single 25-solar-mass magnetorotational hypernova. Such a hypernova could produce not only the r-process elements, but also light elements during stellar evolution, and iron-peak elements during explosive nuclear burning. Hypernovae are often associated with long-duration γ-ray bursts in the nearby Universe
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. This connection indicates that similar explosions of fast-spinning strongly magnetized stars occurred during the earliest epochs of star formation in our Galaxy.
Observations of an extremely metal-poor star suggest that rapidly rotating massive stars with large magnetic fields were a source of r-process elements in the early Universe.