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Modelling SN Type II: microphysics

Modelling SN Type II: microphysics. From Woosley et al. (2002) Woosley Lectures. Solar-system composition. The s and r processes. Solar-system isotopic composition. Arnett: Supernovae and nucleosynthesis. Solar-system isotopic composition. -2. -4. -2. -6. -8. -10.

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Modelling SN Type II: microphysics

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  1. Modelling SN Type II: microphysics From Woosley et al. (2002) Woosley Lectures

  2. Solar-system composition

  3. The s and r processes

  4. Solar-system isotopic composition Arnett: Supernovae and nucleosynthesis

  5. Solar-system isotopic composition -2 -4 -2 -6 -8 -10

  6. Solar-system isotopic composition

  7. Solar-system isotopic composition

  8. A little on the equation of state

  9. Actually the dimensions of Y are Mole/gm and NA has dimensions particles per Mole.

  10. gram T

  11. Zentralfriedhof Vienna, Austria S = k log W T

  12. For radiation:

  13. for ideal gas plus radiation dividing by NA k makes s dimensionless

  14. Reif Fundamentals of Statistical and Thermal Physics McGraw Hill expression Cox and Guili Principles of Stellar Structure Second edition A. Weiss et al Cambridge Scientific Publishers Cox and Guili (24.76b) Note: here  has a different definition

  15. For an ideal gas i.e., non-relativistic, non- degenerate

  16. The entropy of most massive stars is predominantly due to electrons and ions. Radiation is ~10% correction.

  17. Implication: The Chandrasekhar mass will be relevant to the late evolution of the core

  18. Iben (1985; Ql. J. RAS 26, 1)

  19. Woosley et al (2002; RMP 74, 1015)

  20. Burning Stages in the Life of a Massive Star 0 11,000 Woosley et al (2002; RMP 74, 1015)

  21. Stellar Neutrino Energy Losses (see Clayton p. 259ff, especially 272ff) 1) Pair annihilation

  22. Want energy loss per cm3 per second. Integrate over thermal distribution of e+ and e- velocities. These have, in general, a Fermi-Dirac distribution. Fermi Integral -

  23. Clayton (Sect. 3.6) and Lang in Astrophysical Formulae give some approximations (not corrected for neutral currents) T9 < 2 v cancels v-1 in s

  24. More frequently we use the energy loss rate per gram per second

  25. Beaudet et al. (1967; ApJ 150, 979)

  26. 2) Photoneutrino process:(Clayton p. 280) Analogue of Compton scattering with the outgoing photon replaced by a neutrino pair. The electron absorbs the extra momentum. This process is only of marginal significance in stellar evolution – a little during helium and carbon burning. n When non-degenerate and non- relativistic Pphoto is proportional to the density (because it depends on the electron abundance) and en,photo is independent of the density. At high density, degeneracy blocks the phase space for the outgoing electron. e- W- g e-

  27. Beaudet et al. (1967; ApJ 150, 979)

  28. 3) Plasma Neutrino Process: (Clayton 275ff)

  29. A photon of any energy in a vacuum cannot decay into e+ and e- because such a decay would not simultaneously satisfy the conservation of energy and momentum (e.g., a photon that had energy just equal to 2 electron masses, hn = 2 mec2, would also have momentum hn/c = 2mec, but the electron and positron that are created, at threshold, would have no kinetic energy, hence no momentum. Such a decay is only allowed when the photon couples to matter that can absorb the excess momentum. The common case is a g-ray passing of over 1.02 MeV passing near a nucleus, but the photon can also acquire an effective mass by propagating through a plasma.

  30. Plasma frequency

  31. Plasmon dynamics An electromagnetic wave propagating through a plasma has an excess energy above that implied by its momentum. This excess is available for decay

  32. Plasmon dynamics A”plasmon” is a quantized collective charge oscillation in an ionized gas. For our purposes it behaves like a photon with rest mass. The frequency of these oscillations is given by the plasma frequency: increases with density suppression for degeneracy

  33. For moderate values of temperature and density, raising the density implies more energy in the plasmon and raising the temperature excites more plasmons. Hence the loss rate increases with temperature and density.

  34. This is a relevant temperature for Type Ia supernovae Beaudet et al. (1967; ApJ 150, 979)

  35. Festa and Ruderman (1969) Itoh et al (1996) 5) Neutral current excited state decay – not very important. maybe assists in white dwarf cooling. Crawford et al. ApJ, 206, 208 (1976)

  36. Neutrino loss mechanisms = 106 T93 Itoh et al. (1989; ApJ 339, 354)

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