astroparticle physics 1. stellar astrophysics and solar neutrinos alberto carramiñana instituto...

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