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Life of a Star

How these connect

Main sequence (core hydrogen burning) and what it relates to. Every line is an evidence-backed relation, and the arrangement is fixed — this address draws this picture, today and next year.

part_of — Core hydrogen fusion by the proton-proton chain or the CNO cycle is what defines the main-sequence phase.evidence_for — The main sequence is visible as a distinct diagonal population on a luminosity-temperature plot, which is how the phase was identified before any theory of it existed.governs — Models place the crossover from proton-proton to CNO dominance near 1.3 solar masses, because the CNO rate is far more temperature-sensitive.governs — Position along the main sequence, core temperature, dominant fusion cycle and lifetime are all set principally by initial mass.precedes — Core hydrogen exhaustion ends the main sequence and begins shell burning and envelope expansion.constrained_by — Below roughly 0.07 to 0.09 solar masses, depending on composition, a contracting object never ignites sustained hydrogen fusion and becomes a brown dwarf.precedes — Contraction ends and the main sequence begins at the moment core fusion supplies the entire radiated luminosity.depends_on — About 98.5 per cent of the Sun's present energy output comes from the proton-proton chain and about 1.5 per cent from the CNO cycle.instance_of — The Sun is a G-type main-sequence star currently fusing hydrogen in its core.Initial stellar massInitial stellar massHertzsprung-Russell diagramHertzsprung-Russell diagr…ProtostarProtostarThe SunThe SunMain sequence (core hydrogen burning)Main sequence (core hydro…Red giant and asymptotic giant branchRed giant and asymptotic …Hydrogen fusion: the proton-proton chain and the CNO cycleHydrogen fusion: the prot…
7 drawn · 12 reachable and not drawn · positions derived from object ids, never from a simulation
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Every relation drawn, in words9
  1. Hydrogen fusion: the proton-proton chain and the CNO cycle · part_of · Main sequence (core hydrogen burning)

    Core hydrogen fusion by the proton-proton chain or the CNO cycle is what defines the main-sequence phase.

  2. Hertzsprung-Russell diagram · evidence_for · Main sequence (core hydrogen burning)

    The main sequence is visible as a distinct diagonal population on a luminosity-temperature plot, which is how the phase was identified before any theory of it existed.

  3. Initial stellar mass · governs · Hydrogen fusion: the proton-proton chain and the CNO cycle

    Models place the crossover from proton-proton to CNO dominance near 1.3 solar masses, because the CNO rate is far more temperature-sensitive.

  4. Initial stellar mass · governs · Main sequence (core hydrogen burning)

    Position along the main sequence, core temperature, dominant fusion cycle and lifetime are all set principally by initial mass.

  5. Main sequence (core hydrogen burning) · precedes · Red giant and asymptotic giant branch

    Core hydrogen exhaustion ends the main sequence and begins shell burning and envelope expansion.

  6. Protostar · constrained_by · Initial stellar mass

    Below roughly 0.07 to 0.09 solar masses, depending on composition, a contracting object never ignites sustained hydrogen fusion and becomes a brown dwarf.

  7. Protostar · precedes · Main sequence (core hydrogen burning)

    Contraction ends and the main sequence begins at the moment core fusion supplies the entire radiated luminosity.

  8. The Sun · depends_on · Hydrogen fusion: the proton-proton chain and the CNO cycle

    About 98.5 per cent of the Sun's present energy output comes from the proton-proton chain and about 1.5 per cent from the CNO cycle.

  9. The Sun · instance_of · Main sequence (core hydrogen burning)

    The Sun is a G-type main-sequence star currently fusing hydrogen in its core.