1. GEOL3045: Planetary Geology Lysa Chizmadia 11 Jan 2007 The Big Bang & Nucleosynthesis Lysa Chizmadia 11 Jan 2007 The Big Bang & Nucleosynthesis

2. Introduction  Parts of an atom:  Protons (p + ): +’ly charged particles in nucleus, mass ~ 1 atomic mass  Neutrons (n 0 ): 0 charged particles in nucleus, mass ~ 1 atomic mass  Electrons (e - ): -’ly charged particles in nucleus, mass = 5.45 x 10 -4 atomic masses [= 1/ 1836 of p + mass]  Definition of an isotope:  Different # of n 0 s  Same element, different atomic mass  E.g. Oxygen  16 O = 8 p + s and 8 n 0 s  17 O = 8 p + s and 9 n 0 s  18 O = 8 p + s and 10 n 0 s  Parts of an atom:  Protons (p + ): +’ly charged particles in nucleus, mass ~ 1 atomic mass  Neutrons (n 0 ): 0 charged particles in nucleus, mass ~ 1 atomic mass  Electrons (e - ): -’ly charged particles in nucleus, mass = 5.45 x 10 -4 atomic masses [= 1/ 1836 of p + mass]  Definition of an isotope:  Different # of n 0 s  Same element, different atomic mass  E.g. Oxygen  16 O = 8 p + s and 8 n 0 s  17 O = 8 p + s and 9 n 0 s  18 O = 8 p + s and 10 n 0 s

3. The Big Bang  Initially universe  Only contains photons (  ), p + s, n 0 s, e - s and e + s  Due to high , particles collide  Pair production  Annihilation  Proton - Neutron Conversion  Initially universe  Only contains photons (  ), p + s, n 0 s, e - s and e + s  Due to high , particles collide  Pair production  Annihilation  Proton - Neutron Conversion Images from: http://aether.lbl.gov/www/tour/elements/early/early_a.html

4. Nucleosynthesis (H & He)  Due to  T, particles don’t stick  With  T, particles stick to form elements  2 Pathways to form H & He:  Due to  T, particles don’t stick  With  T, particles stick to form elements  2 Pathways to form H & He: Images from: http://aether.lbl.gov/www/tour/elements/early/early_a.html Pathway #1Pathway #2

5. Nucleosynthesis (Li & Be)  6 Li = 4 He + 2 H  7 Li = 4 He + 3 H  7 Be = 3 He + 4 He  8 Be = 4 He + 4 He  Finally, cools enough for atoms to capture e - to be neutral  6 Li = 4 He + 2 H  7 Li = 4 He + 3 H  7 Be = 3 He + 4 He  8 Be = 4 He + 4 He  Finally, cools enough for atoms to capture e - to be neutral Images from: http://aether.lbl.gov/www/tour/elements/early/early_a.html

6. Big Bang Nucleosynthesis  So where do the heavier elements originate? Image from: http://aether.lbl.gov/www/tour/elements/element.html Produced during Big Bang

7. Stellar Nucleosynthesis  Initially ~75% H & ~25% He  Not homogeneously distributed  Places of  , become clumps  Clumps collapse into nebulae  Nebula collapses into star   T, P and   Initially ~75% H & ~25% He  Not homogeneously distributed  Places of  , become clumps  Clumps collapse into nebulae  Nebula collapses into star   T, P and  Images from: http://aether.lbl.gov/www/tour/elements/stellar/stellar_a.htmlhttp://aether.lbl.gov/www/tour/elements/stellar/stellar_a.html

8. Stellar Nucleosynthesis  Inside star’s core:  P &  very high  Nuclear fusion  H-burning: H  He  Mass > 1.5 M ,  He-burning: He  C  Inside star’s core:  P &  very high  Nuclear fusion  H-burning: H  He  Mass > 1.5 M ,  He-burning: He  C Images from: http://en.wikipedia.org/wiki/Main_sequence and http://aether.lbl.gov/www/tour/elements/stellar/stellar_a.htmlhttp://en.wikipedia.org/wiki/Main_sequence http://aether.lbl.gov/www/tour/elements/stellar/stellar_a.html = Sunlight

9. Stellar Evolution  Hertzsprung-Russell diagram  Mass > 4 M   H  He  C  Ne  O  Si  Fe  Hertzsprung-Russell diagram  Mass > 4 M   H  He  C  Ne  O  Si  Fe Images from: http://en.wikipedia.org/wiki/Main_sequencehttp://en.wikipedia.org/wiki/Main_sequence

10. Nucleosynthesis Reactions  Mass > 4 M ,  C-burning  12 C + 12 C  20 Ne + 4 He  23 Na + 1 H  24 Mg + n 0  Mass > 8 M ,  Ne-burning:  20 Ne +   16 O + 4 He  20 Ne + 4 He  24 Mg +   Mass > 4 M ,  C-burning  12 C + 12 C  20 Ne + 4 He  23 Na + 1 H  24 Mg + n 0  Mass > 8 M ,  Ne-burning:  20 Ne +   16 O + 4 He  20 Ne + 4 He  24 Mg +   O-burning  16 O + 16 O  28 Si + 4 He  31 P + 1 H  31 S + n 0  31 P + 1 H  30 S + 2 1 H  30 P + 2 2 H  Mass = 8-11 M ,  Si-burning  12 C  16 O  20 Ne  24 Mg  28 Si  32 S  36 Ar  40 Ca  44 Ti  48 Cr  52 Fe  56 Ni  56 Ni decays to 56 Co  56 Fe  t 1/2 = 6 days & 77 days What about elements > Ni?

11. Nucleosynthesis  So where do the heavier elements originate? Image from: http://aether.lbl.gov/www/tour/elements/element.html Produced during Big Bang Stellar Nucleosynthesis

12. Fe has highest binding E  All elements up to Fe release energy (E) when formed (exothermic)  Heavier elements need more energy added (endothermic)  How to add more E to form heavier elements?  All elements up to Fe release energy (E) when formed (exothermic)  Heavier elements need more energy added (endothermic)  How to add more E to form heavier elements? Image from: http://en.wikipedia.org/wiki/Silicon_burning_process

13. Supernovae  With burning of heavier elements, star continues to collapse  Fe breaks down to 4 He, n 0 and p +  Finally no more compression possible  Outer layers bounce off core  Supernova occurs  Releases neutrons  With burning of heavier elements, star continues to collapse  Fe breaks down to 4 He, n 0 and p +  Finally no more compression possible  Outer layers bounce off core  Supernova occurs  Releases neutrons Images from: http://aether.lbl.gov/www/tour/elements/stellar/stellar_a.html

14. Supernovae Processes  R-process: rapid neutron capture  Occurs over seconds  S-process: slow neutron capture  Occurs over 1000s of years  P-process: knocks out neutrons  Results in proton-rich isotopes  rP-process: rapid proton capture  Occurs over seconds  Cannot progress > Te  R-process: rapid neutron capture  Occurs over seconds  S-process: slow neutron capture  Occurs over 1000s of years  P-process: knocks out neutrons  Results in proton-rich isotopes  rP-process: rapid proton capture  Occurs over seconds  Cannot progress > Te Image from: http://en.wikipedia.org/wiki/S-process

15. Chart of the Nuclides  Red = stable  Blue = extremely short half lives  For more info:  http://en.wikipedia.org/wiki/Isotope_table_ %28complete%29  Red = stable  Blue = extremely short half lives  For more info:  http://en.wikipedia.org/wiki/Isotope_table_ %28complete%29 Image from: http://en.wikipedia.org/wiki/Main_sequencehttp://en.wikipedia.org/wiki/Main_sequence

16. Summary  1) Only H, He, Li & Be produced during Big Bang  Initially only energy & sub-atomic particles existed  With  T, particles collided to form atoms  2) Elements up to Fe produced by stellar nucleosynthesis  Larger star produce heavier elements  3) All elements heavier than Fe produced in supernovae  Neutron capture  Proton capture  1) Only H, He, Li & Be produced during Big Bang  Initially only energy & sub-atomic particles existed  With  T, particles collided to form atoms  2) Elements up to Fe produced by stellar nucleosynthesis  Larger star produce heavier elements  3) All elements heavier than Fe produced in supernovae  Neutron capture  Proton capture