Low mass asymptotic giant branch evolution

Becker and Iben (1979, 1980) have studied the evolution of asymptotic giant branch (AGB) stars as a function of mass and composition for M equal to or greater than 3 solar masses. The results of calculations such as those conducted by Becker and Iben may be used to provide input data for calculations of synthetic AGB star populations. However, these calculations fail to produce C stars at the low luminosities required by the observations. A possible reason for this situation is the lack of input data for masses in the approximate range from 1 to 3 solar masses in the synthetic AGB populations. A critical parameter is the initial mass MH(1) of the hydrogen-exhausted core at the first (major) thermal pulse. The primary objective of the present investigation is the determination of MH(1) as a function of composition and mass (between 1 and 3 solar masses). The obtained results are presented in a graph.