Sun. Suppose 4 × 1026Js-1 is the (oral rate at which the Sun radiates energy at the present time.
(a) Find the total energy of the Sun available for radiation on the rough assumptions that the energy source is the conversion of hydrogen (atomic weight 1.0078) to helium (atomic weight 4.0026) and that the react ion stops when 10 percent of the original hydrogen has been converted to helium. Use the Einstein relation E = (ΔM)c2.
(b) Use (a) to estimate the life expectancy of the Sun. It is be1ievd that the age of the universe is about 10 × 109 years. (A good discussion is given in the books by Peebles arid by Weinberg, cited Hi the general references.)