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We investigate the effect of helium enrichment on the evolution andnucleosynthesis of low-mass asymptotic giant branch (AGB) stars of 1.7Msun and2.36Msun with a metallicity of Z=0.0006 ([Fe/H] = -1.4). We calculateevolutionary sequences with the primordial helium abundance (Y = 0.24) and withhelium-enriched compositions (Y = 0.30, 0.35, 0.40). For comparison wecalculate models of the same mass but at a lower metallicity Z=0.0003 ([Fe/H] =-1.8) with Y=0.24. Post-processing nucleosynthesis calculations are performedon each of the evolutionary sequences to determine the production of elementsfrom hydrogen through to bismuth. Elemental surface abundance predictions andstellar yields are presented for each model. The models with enriched heliumhave shorter main sequence and AGB lifetimes, and enter the AGB with a moremassive hydrogen exhausted core than the primordial helium model. The mainconsequences are 1) low-mass AGB models with enhanced helium will evolve morethan twice as fast, giving them the chance to contribute sooner to the chemicalevolution of the forming globular clusters, and 2) the stellar yields will bestrongly reduced relative to their primordial helium counterparts. An increaseof Delta Y = 0.10 at a given mass decreases the yields of carbon by up to ~60%,of fluorine by up to 80%, and decreases the yields of the s-process elementsbarium and lanthanum by about 45%. While the yields of first s-process peakelements strontium, yttrium and zirconium decrease by up to 50%, the yields ofrubidium either do not change or increase.

Nucleosynthesis in helium-enriched asymptotic giant branch models: Implications for Heavy Element Enrichment in Omega Centauri