Asymptotic Giant Branch Stars

Hydrostatic nucleosynthesis modifies the internal composition of low and intermediate mass stars(M <8M e) ), but only in few cases these changes may affect the overall composition of the Galaxy. Their C-O core, where most of the nucleosynthesis occurred, is left as a dead white dwarf or is completely modified by explosive nucleosynthesis in close binary system during SNIa explosion. However, these stars can take part in the chemical evolution of the Galaxy when the external convection penetrates into an inner region previously enriched with the products of the nuclear burning (dredge up). This chemically modified envelope is then dispersed into the interstellar medium by stellar winds. A partial H-burning may also occur directly in the deepest zones of the convective envelope, if its temperature exceeds 20 — 30.106K.