Thermal pulses; p-capture, alpha-capture, s-process nucleosynthesis; and convective mixing in a star of intermediate mass

Schwarzschild and Haerm (1967), and Sanders (1967) have suggested that the synthesis of elements by slow neutron capture on iron and on elements heavier than iron may take place in stars undergoing thermal pulses. The drawbacks of the various specific mechanisms that have been proposed by various investigators are pointed out, noting at the same time that all the mechanisms have one common feature - many repeated neutron bursts separated by long periods of quiescence - which seems to be a crucial element in obtaining a cosmic distribution of s-process elements. A scheme capable of producing repeated neutron bursts and bringing neutron-capture products to the surface is proposed for stars experiencing thermal pulses.