On Low Mass AGB Stars

Abstract

Recent results on low mass AGB stars are presented. Observed amounts of AGB mass loss imply that thermal pulses will only be encountered for stars of initial mass less than about 4M⊙ for Pop I and 3 M⊙ for Pop II. Mc – L, Me – τif, and Mc – Tb relations are summarized. Carbon dredge-up has been found in low mass stars of both Pop I and Pop II; the mixing length parameter α is crucial to dredge-up, and its value must be normalized according to each author's opacities and mixing length treatment (e.g., via the Sun's Te and L). The “carbon star mystery” is nearing a solution, but a new “s-process mystery” has appeared: only in a narrow range of mass and metallicity have theoretical models been found that encounter the semiconvective 13C s-process mechanism.