Encyclopedia of Astrobiology

2015 Edition
| Editors: Muriel Gargaud, William M. Irvine, Ricardo Amils, Henderson James (Jim) CleavesII, Daniele L. Pinti, José Cernicharo Quintanilla, Daniel Rouan, Tilman Spohn, Stéphane Tirard, Michel Viso


Reference work entry
DOI: https://doi.org/10.1007/978-3-662-44185-5_1392


The r-process is one of the two main nucleosynthesis processes forming nuclei heavier than those of the iron peak, on the neutron-rich side of the nuclear stability valley. Neutron captures occur on timescales of ms, that is, short with respect to those of beta-decays (hence the r-, for rapid), driving the process far into the region of unstable, very neutron-rich nuclei (the “neutron-drip” line). The large neutron amounts required for the process are found either in the innermost regions of core collapse  supernovae or in the collisions of neutron stars. About half of the natural nuclides heavier than iron, including the heaviest ones (thorium and uranium) are produced by the r-process.

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© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  1. 1.Institut d’Astrophysique de ParisParisFrance