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Jakub Skowronski
All curiosities

Curiosity15 M☉

If 14N(p,γ)15O were twice as fast, this model of a 15 M☉ star's core would make about twice the power (×1.9) and run out of hydrogen in half the time (−49%).

  • Biggest knock-on effect: 16O (×2.0).

The CNO cycle's slowest step sets the temperature at which a massive star burns hydrogen.

One-zone model at 35 MK over 6.4 million years. Real stars adjust. The energy is that of this gas at the model's temperature, not the star's luminosity: a real star would adjust its temperature to keep its luminosity. Doubling is a what-if, not the rate's actual uncertainty. How well this rate is known: improving.

Try itHow we know this rate
Rate:
14N(p,γ)15O — G. Imbriani et al (2005), Eur. Phys. J. A 25, 455; REACLIB im05
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