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Almost several decades after the discovery of the first multiple populationsin galactic globular clusters (GC) the debate on their formation is stillextremely current and NGC2808 remains one of the best benchmark to test anyscenario for their origin and the evolution. In this work we focus on thechemical composition of stars belonging to the extreme He-rich populationpopulated by stars with the most extreme abundance of Mg, Al, Na, O and Si. Wechecked whether the most recent measures are consistent with the AGB yields ofstars of $6.5-8~M_{\odot}$. These stars evolve on time scales of the order of40-60 Myr and eject matter strongly enriched in helium, owing to a deeppenetration of the surface convective zone down to regions touched by CNOnucleosynthesis occurring after the core He-burning phase. Since the bigunknown of the AGB phase of massive stars is the mass loss, we propose a newapproch that takes into account the effects of the radiation pressure on dustparticles. We show that this more realistic description is able to reproducethe observed abundances of Mg, Al, Na and Si in these extreme stars. The largespread in the oxygen abundances is explained by invoking deep mixing during theRGB phase. It will be possible to check this work hypothesis as soon as theoxygen measurements of the main sequence stars of NGC2808 will be available.

Self-enrichment in Globular Clusters: the extreme He-rich population of NGC 2808