Revealing the Photodissociation Region: Hubble Space Telescope/NICMOS Imaging of NGC 7027

We report results from a Hubble Space Telescope (HST) and Near-InfraredCamera and Multiobject Spectrometer (NICMOS) program to study the distributionof hot neutral (molecular hydrogen) and ionized circumstellar material in theyoung planetary nebulae NGC 7027. HST/NICMOS provided very high spatialresolution imaging in line and continuum emission, and the stability and largedynamic range needed for investigating detailed structures in the circumstellarmaterial. We present dramatic new images of NGC 7027 that have led to a newunderstanding of the structure in this important planetary nebula. The centralstar is clearly revealed, providing near-infrared fluxes that are used todirectly determine the stellar temperature very accurately (T = 198,000 K). Itis found that the photodissociation layer as revealed by near-infraredmolecular hydrogen emission is very thin, and is biconical in shape. Theinterface region is structured and filamentary, suggesting the existence ofhydrodynamic instabilities. We discuss evidence for the presence of one or morehighly collimated, off-axis jets that might be present in NGC 7027. Theevolutionary future of NGC 7027 is discussed