Astroparticle physics 1. stellar astrophysics and solar neutrinos

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Astroparticle physics1. stellar astrophysics
and solar neutrinos

• Alberto Carramiñana
• Instituto Nacional de Astrofísica, Óptica y
  Electrónica
• Tonantzintla, Puebla, México
• Xalapa, 2 August 2004

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Stellar classification

• Spectroscopic lines ? need for spectral
  classification.
• Types OBAFGKM ? temperature sequence.

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Spectral classification

• Spectral line strengths following Saha law.

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HR diagram

• Hertzsprung (1905) correlation between spectral
  type (? colour ? temperature) and absolute
  magnitudes (? luminosities).
• Russell (1914) first color-magnitude (HR)
  diagram.

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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
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Hipparcos nearby stars
L 4?R2?Te4
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Mass luminosity relation

• Masses measured / estimated in binary stars.

Approx L ? M4
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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

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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
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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.
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Solar p-p Gamow peak
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Hydrogen burning pp chains

• Proton-proton
• I
• II
• III

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CNO chains and He burning

• Hydrogen burning can also proceed through the
  temperature sensitive CNO chain
• Helium burning requires higher temperatures

At 108K ?
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Stellar models

• Stellar models input M X, Y, Z
• Solar reaction are pp and CNO (lt8).
• More massive star models have to incorporate
  he-burning and ?-captured creations to Ne (medium
  mass) or reactions up to Fe.

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Stellar evolution
From Iben (1967)
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The standard solar model

• M 1 M?, X0.73, Y0.25, Z0.02
• X0.7078, Y0.2734 (Bahcall Pinsonneault 2004)

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Solar evolution

• Helium enrichment at core ? higher temp.

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Solar Neutrinos predicted
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Solar neutrino predictions and measurements
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Neutrino oscillations

• Neutrino flavor eigenstates as superposition of
  mass eigenstates.
• In vacuum and/or matter (MSW effect).
• Oscillations confirmed with KamLAND.

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Neutrino oscillations

• Vacuum or matter (MSW effect)?

?e survival probability Low E ? MSW
dominated High E ? vacuum dominated
MSW
Vacuum
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Neutrino oscillation parameters