Heavy element abundances in planetary nebulae: A theorist's perspective

Abstract

The determination of heavy element abundances from planetary nebula (PN) spectra provides an exciting opportunity to study the nucleosynthesis occurring in the progenitor asymptotic giant branch (AGB) star. We perform post-processing calculations on AGB models of a large range of mass and metallicity to obtain predictions for the production of neutron-capture elements up to the first s-process peak at strontium. We find that solar metallicity intermediate-mass AGB models provide a reasonable match to the heavy element composition of Type I PNe. Likewise, many of the Se and Kr enriched PNe are well fitted by lower mass models with solar or close-to-solar metallicities. However the most Kr-enriched objects, and the PN with sub-solar Se/O ratios are difficult to explain with AGB nucleosynthesis models. Furthermore, we compute s-process abundance predictions for low-mass AGB models of very low metallicity ([Fe/H] =-2.3) using both scaled solar and an alpha-enhanced initial composition. For these models, O is dredged to the surface, which means that abundance ratios measured relative to this element (e.g., [X/O]) do not provide a reliable measure of initial abundance ratios, or of production within the star owing to internal nucleosynthesis.

5 pages, presentation at the workshop on the Legacies of the Macquarie/AAO/Strasbourg H-alpha Planetary Nebula project, accepted for publication in PASA

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Cited by in corpus (14)

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• Evolution and nucleosynthesis of asymptotic giant branch stellar models of low metallicity
• The First Stars: A Low-Mass Formation Mode
• Planetary Nebulae: Sources of Enlightenment
• A barium central star binary in the Type-I diamond ring planetary nebula Abell 70
• The Origin and Evolution of the Halo PN BoBn 1: From a Viewpoint of Chemical Abundances Based on Multiwavelength Spectra
• SALT reveals the barium central star of the planetary nebula Hen 2-39
• Is the Sulphur Anomaly in Planetary Nebulae Caused by the s-Process?
• C/O ratios in planetary nebulae with dual-dust chemistry from faint optical recombination lines
• Experimental Photoionization Cross-Section Measurements in the Ground and Metastable State Threshold Region of Se+
• CNO and F abundances in the barium star HD 123396
• Medium-resolution s-process Element Survey of 47 Tuc giant stars
• New Atomic Data for Trans-Iron Elements and Their Application to Abundance Determinations in Planetary Nebulae
• Ongoing surveys for close binary central stars and wider implications