2010MNRAS.403.1413K

An updated grid of stellar yields for low- to intermediate-mass thermally pulsing asymptotic giant branch (AGB) stars is presented. The models cover a range in metallicity Z = 0.02, 0.008, 0.004 and 0.0001, and masses between 1 and 6M_☉. New intermediate-mass (M ≥ 3M_☉) Z = 0.0001 AGB models are also presented, along with a finer mass grid than used in previous studies. The yields are computed using an updated reaction rate network that includes the latest NeNa and MgAl proton capture rates, with the main result that between ∼6 and 30 times less Na is produced by intermediate-mass models with hot bottom burning. In low-mass AGB models, we investigate the effect, on the production of light elements, of including some partial mixing of protons into the intershell region during the deepest extent of each third dredge-up episode. The protons are captured by the abundant ¹²C to form a ¹³C pocket. The ¹³C pocket increases the yields of ¹⁹F, ²³Na, the neutron-rich Mg and Si isotopes, ⁶⁰Fe and ³¹P. The increase in ³¹P is by factors of ∼4 to 20, depending on the metallicity. Any structural changes caused by the addition of the ¹³C pocket into the He intershell are ignored. However, the models considered are of low mass and any such feedback is likely to be small. Further study is required to test the accuracy of the yields from the partial-mixing models. For each mass and metallicity, the yields are presented in a tabular form suitable for use in galactic chemical evolution studies or for comparison to the composition of planetary nebulae.