Observations and Theories of Mixing in Red Giants

摘要: Available data on abundances, luminosities, masses, technetium line strengths, and other properties of the peculiar red giants disk population are reviewed in order to provide a set observational constraints proposed theories mixing nucleosynthesis during advanced giant evolution. The observations suggest that occurs stars all ages, compositions, sets by core mass about 0.5 M⊙ double-shell models, either terminates 0.8 or is stochastic nature, with different probabilities for same initial composition. Evidence concerning s-process abundance distributions, Mg Ti isotopic ratios these imply 22Ne(α,n)25Mg not neutron source most observed giants, which have small masses. None satisfied existing stellar evolution calculations. A number potentially important physical effects may lead mixing, involving turbulence phenomena, magnetic fields, rotational instabilities, reviewed.