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Astroparticle physics 1. stellar astrophysics and solar neutrinos Alberto Carramiñana Instituto Nacional de Astrofísica, Óptica y Electrónica Tonantzintla, Puebla, México Xalapa, 2 August 2004 Stellar classification • Spectroscopic lines need for spectral classification. • Types OBAFGKM temperature sequence. Spectral classification • Spectral line strengths following Saha law. HR diagram • Hertzsprung (1905): correlation between spectral type ( colour temperature) and absolute magnitudes ( luminosities). • Russell (1914): first color-magnitude (HR) diagram. Luminosity classes • • • • • • Ia: luminous supergiants Ib: less luminous... II: bright giants. III: normal giants. IV: subgiants. V: main sequence (dwarfs). • VI,sd: subdwarfs • D: white dwarfs. Sun is a G2V star Hipparcos nearby stars L = 4R2Te4 Mass – luminosity relation • Masses measured / estimated in binary stars. Approx L M4 Modelling stellar strcuture • Basic equations (assumptions): – mass conservation – hydrostatic equilibrium • a polytrope can now be built (before thermodynamics!) – equation of state (gas & radiation) – energy transport (radiative & convective) – energy production Mass composition • = mean molecular weight • X = hydrogen, Y = helium, Z = “metals” • Stellar evolution models: X(t), Y(t), Z(t). 1/2 1/15.5 Stellar energy production • Nuclear reactions: collision and strong force capture vs Coulomb repulsion. – Maxwell distribution vs tunelling penetration function: Gamow peak. Gamow peak depends on temperature and composition of colliding nuclei. Solar p-p Gamow peak Hydrogen burning: pp chains • Proton-proton: – I: – II: – III: CNO chains and He burning • Hydrogen burning can also proceed through the temperature sensitive CNO chain • Helium burning requires higher temperatures At 108K Stellar models • Stellar models input: M & {X, Y, Z} • Solar reaction are pp and CNO (<8%). • More massive star models have to incorporate he-burning and -captured creations to Ne (medium mass) or reactions up to Fe. Stellar evolution From Iben (1967) The standard solar model • M = 1 M, X=0.73, Y=0.25, Z=0.02 • X=0.7078, Y=0.2734 (Bahcall & Pinsonneault 2004) Solar evolution • Helium enrichment at core higher temp. Solar Neutrinos predicted Solar neutrino predictions and measurements Neutrino oscillations • Neutrino flavor eigenstates as superposition of mass eigenstates. • In vacuum and/or matter (MSW effect). • Oscillations confirmed with KamLAND. Neutrino oscillations • Vacuum or matter (MSW effect)? Vacuum - Matter transitions P 1 0.5 0 E MSW Vacuum e survival probability: Low E MSW dominated High E vacuum dominated Neutrino oscillation parameters