{"section":"evolution","label":"Formation & Evolution","count":12,"generatedAt":"2026-03-20","items":[{"slug":"star-formation-and-molecular-clouds","path":"/evolution/star-formation-and-molecular-clouds/","title":"Star Formation in Giant Molecular Clouds","description":"How cold giant molecular clouds fragment below the Jeans mass into Class 0–III protostars, launch bipolar jets, and set the Initial Mass Function.","questionOrTopic":"How do cold interstellar gas clouds collapse and fragment into newborn stars?","epistemicStatus":"strong-observational-evidence","formula":"M_BE = 1.18 c_s⁴ / √(G³ P_ext) ≈ 1.0 M_☉ (T / 10 K)^{3/2} (n_{H2} / 10^4 cm^{−3})^{−1/2};   dN / dM ∝ M^{−2.35}","keyMetricsCount":4,"sources":["src:jwst-archive","src:ngc-ic-steinicke","src:gaia-dr3"]},{"slug":"main-sequence-stellar-evolution","path":"/evolution/main-sequence-stellar-evolution/","title":"Main-Sequence Evolution & the Faint Young Sun","description":"How core hydrogen fusion increases mean molecular weight μ, why main-sequence stars gradually brighten by ~30–100%, and how mass dictates lifespan.","questionOrTopic":"How does a star change during its main-sequence lifetime while fusing hydrogen into helium?","epistemicStatus":"strong-observational-evidence","formula":"1 / μ ≈ 2 X + (3/4) Y + (1/2) Z;   τ_MS ≈ 10^{10} yr × (M / M_☉) / (L / L_☉) ≈ 10^{10} yr × (M / M_☉)^{−2.5}","keyMetricsCount":4,"sources":["src:gaia-dr3","src:hipparcos-new","src:simbad-cds"]},{"slug":"post-main-sequence-and-red-giants","path":"/evolution/post-main-sequence-and-red-giants/","title":"Red Giants, Helium Flash & AGB Evolution","description":"Why core hydrogen exhaustion makes stars expand into red giants, how the Mirror Principle and Helium Flash work, and how AGB winds form planetary nebulae.","questionOrTopic":"Why does a star swell to 100 times its radius and cool at its surface when its core contracts?","epistemicStatus":"strong-observational-evidence","formula":"(M_ic / M_★)_SC ≈ 0.37 (μ_env / μ_core)² ≈ 0.08;   L_RGB ∝ M_core^7   (Paczyński AGB relation: L_AGB ≈ 59,250 (M_c/M_☉ − 0.52) L_☉)","keyMetricsCount":4,"sources":["src:harris-globulars","src:gaia-dr3","src:gcvs-v5"]},{"slug":"core-collapse-and-stellar-death","path":"/evolution/core-collapse-and-stellar-death/","title":"Core Collapse, Neutrino Heating & Stellar Death","description":"How massive stars (>8 M☉) build an iron core, why photodisintegration and electron capture trigger collapse, and how neutrinos revive the shock.","questionOrTopic":"Why does iron accumulation doom a massive star to catastrophic core collapse in less than a second?","epistemicStatus":"standard-model-consensus","formula":"⁵⁶Fe + γ (≳ 2 MeV) → 13 ⁴He + 4 n − 124.4 MeV;   p + e⁻ → n + ν_e;   v_infall ≈ 0.23 c","keyMetricsCount":4,"sources":["src:ngc-ic-steinicke","src:gwtc-3","src:simbad-cds"]},{"slug":"protoplanetary-disks-and-planet-formation","path":"/evolution/protoplanetary-disks-and-planet-formation/","title":"Protoplanetary Disks & Planet Formation","description":"How micron dust grains in protoplanetary disks overcome the meter-size drift barrier via streaming instability and pebble accretion to build planets.","questionOrTopic":"How do microscopic dust grains in a circumstellar disk grow by 14 orders of magnitude into planets?","epistemicStatus":"standard-model-consensus","formula":"Δv_gas ≈ (1/2) (c_s / v_K)² v_K ≈ 50 m/s;   R_Hill = a (M_proto / (3 M_★))^{1/3}","keyMetricsCount":4,"sources":["src:jwst-archive","src:nasa-exoplanet-archive","src:jpl-horizons"]},{"slug":"planetary-migration-and-system-architecture","path":"/evolution/planetary-migration-and-system-architecture/","title":"Planetary Migration, Resonances & Hot Jupiters","description":"How Type I and Type II disk torques, mean-motion resonant chains, planet-planet scattering, and Kozai-Lidov cycles sculpt exoplanet orbits.","questionOrTopic":"How do gas giants end up in 3-day 'hot Jupiter' orbits when they must form beyond the icy snow line?","epistemicStatus":"standard-model-consensus","formula":"P_{i+1} / P_i ≈ (p + q) / p;   L_z = √(1 − e²) cos i ≈ const   (Kozai-Lidov oscillation for i_0 > 39.2°)","keyMetricsCount":4,"sources":["src:nasa-exoplanet-archive","src:jpl-horizons","src:jwst-archive"]},{"slug":"galaxy-formation-and-hierarchical-mergers","path":"/evolution/galaxy-formation-and-hierarchical-mergers/","title":"Galaxy Formation, Cold Streams & Mergers","description":"How dark matter halos assemble hierarchically from the bottom up while baryonic gas cools via cold streams, starburst mergers, and AGN quenching.","questionOrTopic":"How do galaxies form inside dark matter halos and evolve from star-forming disks to quiescent ellipticals?","epistemicStatus":"standard-model-consensus","formula":"T_vir = (μ m_p G M_vir) / (2 k_B R_vir) ≈ 3.6 × 10^5 K × (v_circ / 100 km/s)²;   t_cool = (3 n k_B T) / (2 n_e n_H Λ(T, Z)) < t_dyn","keyMetricsCount":4,"sources":["src:jwst-archive","src:gaia-dr3","src:ngc-ic-steinicke"]},{"slug":"galactic-archaeology-and-stellar-populations","path":"/evolution/galactic-archaeology-and-stellar-populations/","title":"Galactic Archaeology & Stellar Populations","description":"How stellar metallicities [Fe/H], alpha-element ratios [α/Fe], and Gaia phase-space kinematics reconstruct the Milky Way's merger history (Gaia-Enceladus).","questionOrTopic":"How do astronomers use stellar chemistry and orbits as fossils to reconstruct our galaxy's past?","epistemicStatus":"strong-observational-evidence","formula":"[Fe/H] = log_10(N_Fe / N_H)_★ − log_10(N_Fe / N_H)_☉;   [α/Fe] = log_10(N_α / N_Fe)_★ − log_10(N_α / N_Fe)_☉","keyMetricsCount":4,"sources":["src:gaia-dr3","src:harris-globulars","src:simbad-cds"]},{"slug":"supermassive-black-hole-seeds-and-growth","path":"/evolution/supermassive-black-hole-seeds-and-growth/","title":"Supermassive Black Hole Seeds & Co-Evolution","description":"How 10^9 M☉ quasars grew within 700 Myr of the Big Bang: light Pop III seeds vs. heavy direct-collapse black holes, JWST AGN, and the M–σ relation.","questionOrTopic":"How did supermassive black holes grow to a billion solar masses less than 700 million years after the Big Bang?","epistemicStatus":"active-research-frontier","formula":"M(t) = M_seed exp(t / t_Sal),   t_Sal = [η / (1 − η)] (c σ_T) / (4π G m_p) ≈ 45 Myr (at η = 0.1);   M_BH ∝ σ_bulge^{4.4}","keyMetricsCount":4,"sources":["src:eht-m87-sgra","src:jwst-archive","src:simbad-cds"]},{"slug":"stellar-and-supernova-nucleosynthesis","path":"/evolution/stellar-and-supernova-nucleosynthesis/","title":"Stellar & Supernova Nucleosynthesis (B²FH)","description":"How hydrostatic stellar fusion, AGB s-process neutron capture, and supernova explosions synthesize the periodic table from carbon to iron and beyond.","questionOrTopic":"Which astrophysical processes forged each element of the periodic table after the Big Bang?","epistemicStatus":"strong-observational-evidence","formula":"⁴He + ⁴He ⇌ ⁸Be,   ⁸Be + ⁴He → ¹²C* (7.65 MeV) → ¹²C + 2γ;   s-process: τ_n ≫ τ_β   vs.   r-process: τ_n ≪ τ_β","keyMetricsCount":4,"sources":["src:simbad-cds","src:ngc-ic-steinicke","src:gaia-dr3"]},{"slug":"r-process-and-neutron-star-mergers","path":"/evolution/r-process-and-neutron-star-mergers/","title":"The r-Process, Kilonovae & Neutron Star Mergers","description":"How binary neutron star mergers eject neutron-rich matter that synthesizes europium, gold, platinum, and uranium via rapid neutron capture (r-process).","questionOrTopic":"How do neutron star mergers and kilonovae forge the heaviest elements in the universe like gold and uranium?","epistemicStatus":"strong-observational-evidence","formula":"Y_e = n_p / (n_p + n_n) ≲ 0.25 (for 3rd-peak Au/Pt/U);   t_peak ∝ (κ_lanth M_ej / v_ej)^{1/2}","keyMetricsCount":4,"sources":["src:gwtc-3","src:jwst-archive","src:simbad-cds"]},{"slug":"reionization-and-first-stars","path":"/evolution/reionization-and-first-stars/","title":"Cosmic Dawn, First Stars & Reionization","description":"How the Cosmic Dark Ages ended when metal-free Population III stars ignited via H₂ cooling, and how early galaxies reionized intergalactic hydrogen by z ≈ 5.3.","questionOrTopic":"How did the first stars and galaxies end the Cosmic Dark Ages and reionize the universe?","epistemicStatus":"active-research-frontier","formula":"M_J(Pop III, T≈200 K) ≈ 100× M_J(Pop I, T≈10 K);   dQ_{H II} / dt = ṅ_ion / n̄_H − Q_{H II} / t_rec","keyMetricsCount":4,"sources":["src:jwst-archive","src:planck-2018","src:simbad-cds"]}]}