Representative stellar fusion isotope pathways
The ppI branch builds deuterium and helium-3 before combining two helium-3 nuclei.
Key knowledge
The ppI branch builds deuterium and helium-3 before combining two helium-3 nuclei. A representative CN cycle regenerates carbon-12 while converting four protons to helium-4. Triple-alpha burning proceeds through short-lived beryllium-8 and excited carbon-12; carbon-12 can subsequently capture another alpha particle. These are representative pathways, not a complete reaction network.
Values and equations
ppI: p+p→D+e⁺+νₑ; D+p→³He+γ; ³He+³He→⁴He+2p. CN: ¹²C+p→¹³N+γ; ¹³N→¹³C+e⁺+νₑ; ¹³C+p→¹⁴N+γ; ¹⁴N+p→¹⁵O+γ; ¹⁵O→¹⁵N+e⁺+νₑ; ¹⁵N+p→¹²C+⁴He. Triple-alpha: α+α↔⁸Be; ⁸Be+α→¹²C*→¹²C+γ; subsequent capture: ¹²C+α→¹⁶O+γ.
- p,D,α
- proton, deuteron and helium-4 nucleus species
- e⁺,νₑ,γ
- positron, electron neutrino and photon species
- ¹²C*
- excited carbon-12 nucleus species
Conditions and scope
- p denotes a proton, D a deuteron, α a helium-4 nucleus, γ a photon, and νₑ an electron neutrino. Intermediate isotopes, branching, temperature, density and composition determine actual rates; the first two ppI steps occur twice per completion.
- For energy budgets distinguish nuclear from neutral-atom masses, positron annihilation and escaping neutrino energy. No fixed pp/CNO crossover temperature, abundance fit or single two-body rate formula for triple-alpha is asserted.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read pp branches, the six-step main CN cycle, alpha capture and neutrino-heating convention. Checked baryon number, charge and reaction cancellation. Excluded fixed temperature exponents, approximate numerical energy allocations and claimed universal catalyst conservation outside this bounded cycle.
2026-10-10 · Independent AI editorial review: All44 exact root-authored compact records, equations/variable units/conditions and140 origin edges accepted after independently reading final6/18 with bounded primary bodies and matching prior38/122 scientific fingerprints unchanged. Exact claim/edge review is distinct from combined inventory scope and separate CLE26 approval; no entire cited books or old-corpus experimental revalidation is asserted. Receipt: cosmos-completion-independent-content-and-inventory-review.1.
Entry details
Permanent link to this entry ↗- Record identity
- uni-cosmos-stellar-nuclear-isotope-steps
- Revision
- core.1
- Structured reference record
- University core expansion