Infrared detection of Galactic planetary nebulae

This project will investigate techniques for the detection and characterization of planetary nebulae at infrared wavelengths. There are ~3,500 known PN in the Galaxy, with the majority discovered in recent years from Galactic Plane (GP) surveys at optical wavelengths, particularly in H-alpha (e.g. MASH -- Parker et al. 2006; IPHAS -- Sabin et al. 2014). Population estimates from models vary
from ~6000 up to ~45000 depending on whether binarity is a requirement or whether single stars can also form PN. At the moment this is an open question in stellar evolution. There is now a move to
IR detection techniques which are less prone to Galactic extinction and probe longer sightlines. This project will build on the UWISH2 survey, the first imaging survey of the northern GP in the v=1-0S(1) ro-vibrational line of molecular hydrogen (H2) at 2.12 microns (Froebrich et al. 2015), which resulted in the detection of ~300 PN candidates (b= +/- 1.5 degrees), with roughly 2/3 of these being new detections not seen in H-alpha and ~50% having bipolar morphology. The first phase of the project will be to reduce and publish long-slit K-band spectroscopy of a subset of these objects to further determine their PN nature (observations obtained July 2016 at WHT), with appropriate follow-up with Br-gamma and H2 line imaging (proposal submitted) and future possible IFS observations. In the second phase of the project, modelling of the recombination and molecular line emission spectra/images will be explored via PDR models, constrained by the observations (the student will attend the 2017 Cloudy workshop). The aim is to produce a suite of emission line and continuum modesl of PN in the IR as a function of evolutionary stage. This will then allow identification of PN in wide-field and all-sky IR surveys.