Curiosity15 M☉

If ¹³C(p,γ)¹⁴N were twice as fast, this model of a 15 M☉ star's core would end up with a carbon‑12 to carbon‑13 ratio twice as high (×2.0).

Astronomers measure this ratio in red giants; LUNA measured this rate underground in 2023.

One-zone model at 35 MK over 6.4 million 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:: ¹³C(p,γ)¹⁴N — Angulo C. (1999), Nuclear Physics, A656, 3-183; REACLIB nacr
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 13C(p,γ)14N were twice as fast, this model of a 15 M☉ star's core would end up with a carbon‑12 to carbon‑13 ratio twice as high (×2.0).

If ¹³C(p,γ)¹⁴N were twice as fast, this model of a 15 M☉ star's core would end up with a carbon‑12 to carbon‑13 ratio twice as high (×2.0).