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We present updated calculations of stellar evolutionary sequences anddetailed nucleosynthesis predictions for the brightest asymptotic giant branch(AGB) stars in the Galaxy with masses between 5Msun to 9Msun, with an initialmetallicity of Z =0.02 ([Fe/H] = 0.14). In our previous studies we used theVassiliadis & Wood mass-loss rate, which stays low until the pulsation periodreaches 500 days after which point a superwind begins. Vassiliadis & Wood notedthat for stars over 2.5Msun the superwind should be delayed until P ~ 750 daysat 5Msun. We calculate evolutionary sequences where we delay the onset of thesuperwind to pulsation periods of P ~ 700-800 days in models of M = 5, 6, and7Msun. Post-processing nucleosynthesis calculations show that the 6 and 7Msunmodels produce the most Rb, with [Rb/Fe] ~ 1 dex, close to the average of mostof the Galactic Rb-rich stars ([Rb/Fe] ~ 1.4 plus or minus 0.8 dex). Changingthe rate of the 22Ne + alpha reactions results in variations of [Rb/Fe] aslarge as 0.5 dex in models with a delayed superwind. The largest enrichment inheavy elements is found for models that adopt the NACRE rate of the22Ne(a,n)25Mg reaction. Using this rate allows us to best match the compositionof most of the Rb-rich stars. A synthetic evolution algorithm is then used toremove the remaining envelope resulting in final [Rb/Fe] of ~ 1.4 dex althoughwith C/O ratios > 1. We conclude that delaying the superwind may account forthe large Rb overabundances observed in the brightest metal-rich AGB stars.

Heavy Element Nucleosynthesis in the Brightest Galactic Asymptotic Giant Branch stars