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The stars evolving through the asymptotic giant branch (AGB) are generally regarded as one of the most relevant pollutants of the interstellar medium, based on the gas reversed into their surroundings and on the significant amounts of dust produced into their circumstellar envelopes. Despite the significant progresses achieved in the last decades, the description of these stars is still affected by the poor knowledge of some physical mechanisms, primarily mass loss and convection, still largely unknown from first principles. After a general description of the evolution of the stars across the AGB, and of the gas and dust production expected, we will discuss how a valuable assist in the exhaustive comprehension of the evolutionary, structural and chemical properties of this class of stars is provided by the interpretation of the observations of post-AGB sources. |
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