https://doi.org/10.1140/epja/s10050-026-01865-w
Review
The r-process: history, required conditions, astrophysical sites, and observations
1
GSI Helmholtz Center for Heavy Ion Research, Planckstrasse 1, 64291, Darmstadt, Germany
2
Department of Physics, University of Basel, Klingelbergstrasse 82, 4056, Basel, Switzerland
3
Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., 73019, Norman, OK, USA
a
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Received:
29
January
2026
Accepted:
16
April
2026
Published online:
27
May
2026
Abstract
This review of the rapid-neutron-capture (i.e. r-) process starts with determining the Solar System r-abundance pattern via first obtaining (and subtracting) the contribution from the slow-neutron capture (s-) process. We emphasize the extensive work in this area by our late colleague Roberto Gallino and continue in an overview, concentrating on attempts to reproduce the solar r-process pattern with historical site-independent approaches, based on nuclear physics far from stability. In a second step we address the existing proposals for astrophysical sites. Among stellar observations we start with available observations of individual events before analyzing low-metallicity stars, which witness r-process contributions in the early Galaxy. We conclude with a comparison of observations and model predictions, focusing on our present ability to identify the responsible individual astrophysical sites by their imprint in Galactic evolution.
Communicated by Maria Borge.
Friedrich-K. Thielemann and John J. Cowan contributed equally to this work.
© The Author(s) 2026
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