Homework 12, due Oct 5
    
1) For the kinetic temperatures of a cluster of galaxies, T=3x10⁷ K, and for the Orion H II region, T=10⁴ K, what energy in eV does it correspond to?

    T   3x10⁷ K   10⁴ K
    Eₖₜ 2585.2 eV 0.86173 eV


2) What is the closest ionization stage of the six most common elements for those two temperatures, considering just the ionization energy?



      Cluster     Orion
       
    Thermal Average Energy 
    ────────────────────────
      2585.2 eV   0.86173 eV

    Near Ionization Stage
    ────────────────────────
      H I         H I
      He II       He I
      O VIII      O I
      C VI        C I
      Ne X        Ne I
      Fe XXIV     Fe I

    We expect all of the elements to be ionized in the cluster, except iron.


3) Consider the very important case of H 2 , H 0 , and H + . What is the temperature needed to dissociate H 2 and form H 0 , and then to ionize H 0 ?

    H₂[zero point] = -4.5 eV.
        4.5 eV / kᵦ = 5.2×10⁴ K.

    H⁰[zero point] = 13.6 eV.
        13.6 / kᵦ = 1.58×10⁶ K.