Curiosity¹³C pocket

If ⁵⁶Fe(n,γ)⁵⁷Fe were twice as fast, this model of an AGB star's ¹³C pocket would end up with about half as much barium‑138 (−53%).

Biggest knock-on effect: ¹²⁰Sn (−71%).

Iron grabs more of the neutrons, so each nucleus climbs less far towards barium.

One-zone model at 90 MK over 78 000 years. Real stars adjust. Doubling is a what-if, not the rate's actual uncertainty. How well this rate is known: improving.

Try it How we know this rate

Rate:: ⁵⁶Fe(n,γ)⁵⁷Fe — KADONIS V0.3 refit 2017 (2009); REACLIB ks03
Improving:: Recent measurements have narrowed the rate; some uncertainty remains.
Model:: one-zone model; JINA REACLIB reaclib_default2_20250330, pynucastro 3.1.0; 2026-10-13

If 56Fe(n,γ)57Fe were twice as fast, this model of an AGB star's 13C pocket would end up with about half as much barium‑138 (−53%).

If ⁵⁶Fe(n,γ)⁵⁷Fe were twice as fast, this model of an AGB star's ¹³C pocket would end up with about half as much barium‑138 (−53%).