Mid and Far Infrared Photometry of Galactic Planetary Nebulae with the AKARI All Sky Survey

Abstract

We provide mid- and far-infrared photometry of 857 Galactic planetary nebulae (PNe) using data derived from the AKARI All-Sky Survey. These include fluxes at 9 and 18 {\mu}m obtained with the Infrared Camera (IRC), and at 65, 90, 140 and 160 {\mu}m using the far-Infrared Surveyor (FIS). It is noted that the IR luminosities of the youngest PNe are comparable to the total luminosities of the central stars, and subsequently decline to ~ 5102 L where D > 0.08 pc. This is consistent with an evolution of PNe dust opacities, and appreciable absorption in young and proto-PNe. We also note that whilst there is little evidence for the evolution in IR/radio flux ratios suggested by previous authors. The fall-off in dust temperatures is similar to that determined in previous studies, whilst levels of Ly heating are < 0.5 of the total energy budget of the grains. There appears to be an evolution in the infrared excess (IRE) as nebulae expand, with the largest values occurring in the most compact PNe.