Basics Of Astrophysics

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The lecture I made about astrophysics, how a star shine and the fate of a star in our university.

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  • hmmm quite interesting for a newbie to astro physics, i cant quite determine what most of the letters stand for in the equations, perhaps a key could be made?
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Basics Of Astrophysics

  1. 1. Basics of astrophysics
  2. 2. Stars Story  Hydrostatic equilibrium  Mass  Luminosity - Temperature
  3. 3. Proton – Proton Chain  As happens in the core of a typical main sequence star. 0.23% 99.77% 10-5% 15.08% 99.9% 0.1% 84.92%
  4. 4. Neutrino  Leptons  No electrical charge  Passes through ordinary matter
  5. 5. Problem  Determine the maximum size of rotating body with rotation period = 0.033 second
  6. 6. Neutron Stars  The core of a massive star in a supernova  Chandrasekhar limit (12.5)  Stable state  Most 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
  7. 7. Supernova 1987A In LMC
  8. 8. 1987A’s Timeline  Feb.23 7:35am, a total number of 24 neutrons detected  Hours later the visible SN discovered  Neutrinos and antineutrinos reached the earth synchronously : matter, antimatter and photos react the same against gravity  1987A was a blue supergiant!  Missing neutron star
  9. 9. 1987A 1987 was discovered in Feb., but reached the brightest in Mar. AAVSO observations
  10. 10. Rings turning on  Months after SN  Emission lines  UV  The distance: 168,000 ly
  11. 11. Neutrinos in Supernovas  Direct 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
  12. 12. Some Facts  Much 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)
  13. 13. So  Was the total energy released in a SN less than the energy that ionized shell emits?  99% of energy (1046 j) -> neutrinos  Where all these neutrinos come from?
  14. 14. Urca process  (Z-1,A) -> (Z,A) + e- + ν-e  (Z,A) + e- -> (Z-1,A) + νe  Two forms of beta decay  Baryons - Leptons  Gamow, Loosing energy (cooling), Casino Urca
  15. 15. Beta decay Beta Minus Beta Plus Electron Capture
  16. 16. Pulsars  Discovery 1967 as little green men  Neutron stars are low in luminosity (why?)
  17. 17.  Giant atomic nucleus  Fluid Super conductor  Magnetic dipole radiation  Spin periods of pulsars increase by time
  18. 18. Widescreen Test Pattern (16:9) Aspect Ratio Test (Should appear circular) 4x3 16x9

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