1. The high temperatures that would be required (to overcome the electric Coulomb barriers) for fusion of nuclei beyond iron would also result in a large number of high-energy photons. These photons in turn result in photodisintegration of nuclei that suppress any possible charge-particle fusion reactions.
2. H fusion in stars occurs in the inner core (approximately the innermost 10% of the star by mass) and lasts for about 90% of the star's total life. After the exhaustion of H in the core the star will then develop a thin (thousands of km) H fusion shell outside of the inert He core. Later when the temperature rises to above 100 million K the He core will fuse C and O. When the He is finally depleted in the core a thin He fusion shell outside of the now C/O core but interior to the H fusion shell will ignite. These later fusion stages occur only during the last ∼10% of a star's life.
3. Supernovae (SNe) are observationally categorized by the presence (type II) or absence (type I) of hydrogen spectral lines. Further type II SNe are normally thought to result from the collapse and explosion of single massive short-lived stars. Type I SNe are thought to be phenomena of lower-mass longer-lived binary star systems with the eventual explosion and complete destruction of the white dwarf member of the binary.
4. A. G. W. Cameron in Essays in Nuclear Astrophysics C. A. Barnes D. D. Clayton D. N. Schramm Eds. (Cambridge Univ. Press Cambridge 1982) pp. 23–43.