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

L = 4  R 2  T e 4 Hipparcos nearby stars

Mass – luminosity relation Masses measured / estimated in binary stars. Approx L  M 4

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).  1/15.5  1/2

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 10 8 K 

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= (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)? e survival probability: Low E  MSW dominated High E  vacuum dominated MSWVacuum

Neutrino oscillation parameters