Searching for Ha-Selected Planetary Nebulae in the UWISH2 Galactic Plane Molecular Hydrogen Survey

Abstract

This thesis seeks to analyse and quantify the differences present in 2 different emission mechanisms seen in Planetary Nebulae (PN). These are H emission from recombination of ionised hydrogen and H2 emission from photoexcitation of molecular hydrogen gas. Firstly, I have gathered images from the UKIRT Widefield Infrared Survey for H2 (UWISH2), which correspond to PN in the Macquarie/AAO/Strasbourg H (MASH) Planetary Nebula Galactic Cataloge, which have been compared and contrasted, and the full extent of which will be featured in the appendices of this report. Secondly, I have gathered images from the UWISH2, which correspond to PN found in the INT/WFC Photometric H Survey (IPHAS) of the Northern Galactic plane by Viironen et al. 2009, which have been compared and contrasted and will be featured in the appendices of this report. The results gained from this work challenge the assumption of Gatley's Rule that molecular hydrogen is a predictor for bipolar emission in PN with more than half of the PN in the MASH sample showing such emission, and approximately 80% of the PN in the IPHAS sample as well. This work has shown that H2 emission is a good method of searching for PN and may further be used as a tool to further confirm objects as true PN.