Reduce, Reuse, Recycle: Planetary Nebulae as Green Galactic Citizens

TL;DR

This paper reviews planetary nebulae as tools for understanding stellar evolution and galactic chemical composition, highlighting their dual role as metallicity archives and sources of processed elements, and discusses current analysis methods and discrepancies.

Contribution

It provides a comprehensive review of gas-phase abundance analysis in planetary nebulae, comparing observational data with theoretical models and identifying areas for future research.

Findings

Abundance measurements vary depending on analysis methods.

Observational data generally align with AGB stellar yield predictions.

Discrepancies highlight the need for improved analysis techniques.

Abstract

We review gas-phase abundances in PNe and describe their dual utility as archives of original progenitor metallicity via the alpha elements, as well as sources of processed material from nucleosynthesis during the star's evolution, i.e., C, N, and s-process elements. We describe the analysis of PN spectra to derive abundances and discuss the discrepancies that arise from different choices at each step. Abundance results for the Milky Way and Magellanic Clouds from various groups of investigators are presented; the observational results are compared with theoretical predictions of AGB stellar yields. Finally, we suggest areas where more work is needed to improve our abilities to determine abundances in PNe.