ReviewBasics of astrophysics

Stars StoryHydrostatic equilibriumMassLuminosity - Temperature

pp pep

7 Be

hep

8 B

ppI ppII ppIII

Proton – Proton Chain As happens in the core of a typical main

sequence star.99.77% 0.23%

15.08%

99.9% 0.1%

84.92%

10-5%

NeutrinoLeptonsNo electrical chargePasses through ordinary matter

ProblemDetermine the maximum size of rotating body

with rotation period = 0.033 second

Neutron StarsThe core of a massive star in a supernovaChandrasekhar limit (12.5)Stable stateMost SNs produce NSs -> 108 – 109 NSs in

universe

The T of a NS falls from 1012K to 1011 K in 2 seconds

A young NS is about 106 K

Supernova 1987AIn LMC

1987A’s TimelineFeb.23 7:35am, a total number of 24 neutrons

detectedHours later the visible SN discoveredNeutrinos and antineutrinos reached the earth

synchronously : matter, antimatter and photos react the same against gravity

1987A was a blue supergiant!Missing neutron star

1987A1987 was discovered in Feb., but reached the brightest in Mar.

AAVSO observations

Rings turning onMonths after SNEmission linesUVThe distance: 168,000 ly

Neutrinos in SupernovasDirect observation of SNs is impossible Dense gas surrounds SNs, and…Information about the inner most regions of a SN No interaction with matter

Delay of 1987 visible light

First impressions in 1987

Some FactsMuch of the visible light comes from the

decay of radioactive elements produced by the supernova shock wave, and even light from the explosion itself is scattered by dense and turbulent gases.

The neutrino burst is expected to reach Earth before any electromagnetic waves (SNEWS)

SoWas the total energy released in a SN less

than the energy that ionized shell emits?

99% of energy (1046 j) -> neutrinosWhere all these neutrinos come from?

Urca process(Z-1,A) -> (Z,A) + e- + ν-

e

(Z,A) + e- -> (Z-1,A) + νe

Two forms of beta decayBaryons - LeptonsGamow, Loosing energy (cooling), Casino

Urca

Beta decay

Beta Minus

Electron Capture

Beta Plus

PulsarsDiscovery 1967 as little green menNeutron stars are low in luminosity (why?)

Giant atomic nucleusFluid Super conductorMagnetic dipole radiationSpin periods of pulsars increase by time

Widescreen Test Pattern (16:9)

Aspect Ratio Test

(Should appear circular)

16x9

4x3