astroparticle physics 1. stellar astrophysics and solar neutrinos alberto carramiñana instituto...
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Astroparticle physics
1. stellar astrophysics and solar neutrinos
Alberto CarramiñanaInstituto 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 = 4R2Te
4
Hipparcos nearby stars
Mass – luminosity relation
• Masses measured / estimated in binary stars.
ApproxL 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). 1/15.5
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 temperatureand 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
0
0.5
1
E
P
e survival probability:Low E MSW dominatedHigh E vacuum dominated
MSW Vacuum
Neutrino oscillation
parameters