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Presolar Grains as Probes of Supernova Nucleosynthesis.
Space Sci Rev
November 2024
Institute for Geochemistry and Petrology, ETH Zürich, 8092 Zurich, Switzerland.
We provide an overview of the isotopic signatures of presolar supernova grains, specifically focusing on Ti-containing grains with robustly inferred supernova origins and their implications for nucleosynthesis and mixing mechanisms in supernovae. Recent technique advancements have enabled the differentiation between radiogenic (from Ti decay) and nonradiogenic Ca excesses in presolar grains, made possible by enhanced spatial resolution of Ca-Ti isotope analyses with the Cameca NanoSIMS (Nano-scale Secondary Ion Mass Spectrometer) instrument. Within the context of presolar supernova grain data, we discuss () the production of Ti in supernovae and the impact of interstellar medium heterogeneities on the galactic chemical evolution of Ca/Ca, () the nucleosynthesis processes of neutron bursts and explosive H-burning in Type II supernovae, and () challenges in identifying the progenitor supernovae for Cr-rich presolar nanospinel grains.
View Article and Find Full Text PDFHigh-temperature Tl decay clarifies Pb dating in early Solar System.
Nature
November 2024
GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany.
Article Synopsis
- Radioactive nuclei that live for millions of years help us understand the Sun's formation and the nucleosynthesis happening when it was born, with lead (Pb) being a key example.
- Recent measurements of the weak decay of ionized thallium (Tl) provided a more accurate half-life, which was found to be 4.7 times longer than previously thought, thus reducing uncertainty in our calculations.
- Using these improved decay rates, researchers calculated lead yields in asymptotic giant branch (AGB) stars, confirmed isolation times for solar material, and validated the theory that the Sun formed in a long-lived molecular cloud.
Preferential occurrence of fast radio bursts in massive star-forming galaxies.
Nature
November 2024
Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA, USA.
Fast radio bursts (FRBs) are millisecond-duration events detected from beyond the Milky Way. FRB emission characteristics favour highly magnetized neutron stars, or magnetars, as the sources, as evidenced by FRB-like bursts from a galactic magnetar, and the star-forming nature of FRB host galaxies. However, the processes that produce FRB sources remain unknown.
View Article and Find Full Text PDFThe black hole low-mass X-ray binary V404 Cygni is part of a wide triple.
Nature
November 2024
Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
Evidence suggests that, when compact objects such as black holes and neutron stars form, they may receive a 'natal kick', during which the stellar remnant gains momentum. Observational evidence for neutron star kicks is substantial, yet is limited for black hole natal kicks, and some proposed black hole formation scenarios result in very small kicks. Here we report that the canonical black hole low-mass X-ray binary (LMXB) V404 Cygni is part of a wide hierarchical triple with a tertiary companion at least 3,500 astronomical units (AU) away from the inner binary.
View Article and Find Full Text PDFShedding Light on the Origin of ^{204}Pb, the Heaviest s-Process-Only Isotope in the Solar System.
Phys Rev Lett
August 2024
European Organization for Nuclear Research (CERN), Switzerland.
Asymptotic giant branch stars are responsible for the production of most of the heavy isotopes beyond Sr observed in the solar system. Among them, isotopes shielded from the r-process contribution by their stable isobars are defined as s-only nuclei. For a long time the abundance of ^{204}Pb, the heaviest s-only isotope, has been a topic of debate because state-of-the-art stellar models appeared to systematically underestimate its solar abundance.
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