Rapid neutron capture (the r-process)

Assembled from 19 blocks · 2 evidence · 12 related

1. Story
2. The mechanism that builds roughly half the elements heavier than iron, including gold, platinum, thorium and uranium. It requires a neutron flux so intense that a nucleus captures neutrons faster than it can beta-decay, driving matter far to the neutron-rich side of stability before it decays back toward it. The conditions are extreme enough that the astrophysical site was disputed for decades: core-collapse supernovae were the traditional candidate, and neutron-star mergers the theoretical alternative. The 2017 detection of a kilonova following the neutron-star merger GW170817 provided the first direct evidence of r-process material being made in a merger, with ejecta estimates on the order of a few hundredths of a solar mass. Whether mergers alone can account for the Galactic inventory, and whether the very heaviest species were observed at all, remain open. Not a place.
3. Knowledge
4. Stellar nucleosynthesis
5. Rapid neutron capture (the r-process)
6. Connections
7. Stellar nucleosynthesis
8. Kilonova
9. B2FH sets out the synthesis of the elements in stars
10. A neutron-star merger is detected in gravitational waves and light
11. Hydrogen fusion: the proton-proton chain and the CNO cycle
12. The iron peak in nuclear binding energy
13. Rapid neutron capture (the r-process)
14. The first stars form from metal-free gas
15. B2FH sets out the synthesis of the elements in stars
16. A neutron-star merger is detected in gravitational waves and light
17. Evidence
18. Establishes the 17 August 2017 binary neutron-star merger and the associated kilonova AT2017gfo in NGC 4993 at roughly 40 Mpc as a site of r-process nucleosynthesis. Volume and page numbers are deliberately not asserted because they were not confirmed. Ejecta mass estimates of 0.03-0.06 solar masses come from modelling papers summarised via search, not from this paper.
19. Establishes stellar nucleosynthesis as the origin of the elements heavier than helium and organises production into distinct nuclear processes including slow and rapid neutron capture. Title, authors, journal, volume and pages were read from ADS and publisher listings via search; the review itself was not fetched, so the internal process taxonomy is described from secondary accounts.