The Evolution of Planetary Nebulae

Planetary nebulae have an important role in Galactic chemical evolution by returning significant enriched material to the ISM. Observations of planetary nebulae are used to determine the elemental abundances of the interstellar medium present in our own and other galaxies. The chemical properties of a planetary nebula can be determined through plasma diagnostics and empirical analysis using key information carried by the nebular emission lines. The emission lines emitted by a planetary nebulae also carry important information about the kinematics features of the nebula. The kinematic analysis of planetary nebulae provides some insights into the stellar mass-loss process and the planetary nebule evolution.

A considerable fraction of central stars of planetary nebulae exhibit hydrogen-deficient fast-expanding atmospheres characterized by a large mass-loss rate, so called Wolf-Rayet type stars. What are less clear are the physical mechanisms and evolutionary paths that remove the hydrogen-rich outer layer from these degenerate cores, and transform it into a fast stellar wind. The main goal of Ashkbiz Danehkar’s PhD thesis was to determine kinematic properties, physical conditions and chemical abundances for a sample of Galactic planetary nebulae with hydrogen-deficient Wolf-Rayet type central stars using integral field spectroscopic data collected at Siding Spring Observatory, which will provide clues about the origin and formation of their stellar atmospheres.