The Ring Nebula as a laboratory for the interaction of molecules, PAHs and dust in strong UV radiation fields

We propose to observe the Ring Nebula, NGC 6720, at unprecedented spatial resolution and spectral sensitivity using MIRI, NIRSpec and NIRCam, with the aim of measuring and analyzing the emission from a range of atomic, molecular and particulate components commonly found in astrophysical environments. We will use this planetary nebula (PN) as an astrophysical laboratory, with a well-defined geometry and a single exciting central star. With Spitzer, PAH emission and strong mid-IR molecular H2 emission have already been detected from the O-rich PN NGC 6720. We will image the entire nebula in multiple NIRCAM and MIRI filters to enable us to spatially resolve the different gas and PAH components, combining these with high spatial and spectral resolution NIRSpec and MIRI IFU spectroscopy at two positions, one on an isolated clump at the inner edge of the bright ring and the other on the main ring itself. We will use the data to analyze and model the physical conditions in the ionized and molecular gas in order to probe how these, together with the radiation field, influence spatial variations of the PAH charge balance, size and structures deduced from the observed PAH band ratios. This will allow us to investigate how PAHs and other molecules form, evolve and survive in clumpy, irradiated environments.