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Nucleosynthesis and formation of the elements

Nucleosynthesis and formation of the elements. Cosmic abundance of the elements. Mass number. Nucleosynthesis. Big Bang – ca 12 000 Ma Supernova – ca 5 000 Ma Condensation of matter and formation of the known elements . . . In the seconds following the Big Bang.

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Nucleosynthesis and formation of the elements

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  1. Nucleosynthesis and formation of the elements

  2. Cosmic abundance of the elements Mass number

  3. Nucleosynthesis • Big Bang – ca 12 000 Ma • Supernova – ca 5 000 Ma • Condensation of matter and formation of the known elements . . .

  4. In the seconds following theBig Bang Condensation of matter into p and n Formation of the fuel of the stars . . . H et He T  3 x 109 K p + e– n + v 1H + n 2H + g 2H + p 3He + g 3He + n 4He + g

  5. Diagramme Hertzprung-Russel

  6. 1st Generation Stars - H fusion and production of 4He 1H + 1H 2H + b+ + v0.422 MeV 2H + 1H 3He + g5.493 MeV 3He + 3He 4He + 1H + 1H12.859 MeV

  7. 2nd Generation Stars(Our sun today)Fusion by CNO reaction 12C + 1H 13N + g 13N 13C + b+ + v 13C + 1H 14N + g 14N + 1H 15O + g 15O 15N + b+ + v 15N + 1H 12C + 4He

  8. He Fusion in Red Giants (~ 106 to 107 years) 4He + 4He 8Be 8Be + 4He 12C + g 12C burning (<1000 years) 12C + 4He 16O 12C + 12C 20Ne + 4He + g 16O burning (<1 year) 16O + 16O 28Si + 4He + g 12C + 16O 24Mg + 4He + g

  9. End of a Red Giant's life: Si combustion:lasts about 1day 28Si + 4He 32S + g 32S + 4He 36Ar + g 36Ar + 4He 40Ca + g 40Ca + 4He 44Ti + g 44Ca + 2b+ 44Ti + 4He 48Cr + g 48Ti + 2b+ 48Cr + 4He 52Fe 52Cr + 2b+ 52Fe + 4He 56Ni + g 56Fe + 2b+ 56Ni / 56Fe + 4He  impossible . . .

  10. Nuclear binding energy maximum • maximum at 56Fe • after, fusion becomes endothermic • nucleosynthesis beyond 56Fe is by neutron capture • and by fission of nuclides with Z > 90 • (uranium and transuranics) http://www.chem.uidaho.edu/~honors/nucbind.html

  11. Supernovaand 2nd generation stars

  12. Supernova remnants Cygnus Loop (HST): green=H, red=S+, blue=O++ Cas A in x-rays (Chandra) Vela Remnant of SN386, with central pulsar (Chandra) SN1998bu

  13. Nucleosynthesis by n and p capture

  14. CNO Fe: produced in the final stage of fusion Equilibrium burning Elements > Fe:neuton activation in supernova Mg Ar Al Cr Na Ti P Mn Fissionable Elements Cl K Co F V Instable

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