Despite model predictions, many planetary nebulae appear to have a relatively rich molecular content. Observational studies of over 30 such objects show the presence of a variety of gas-phase molecules, from simple species such as CN and CS, to more complex organics including H2CO, HC3N, c-C3H2, and CH3CN. Other PNe contain fullerenes; carbonaceous and silicate dust features are also found. Molecular abundances also do not appear to vary with nebular age. Remnant material from the asymptotic giant branch appears to undergo chemical processing in the protoplanetary nebula phase and then is frozen out in planetary nebulae. PN ejecta are thus in part molecular in content and may account for the observation of complex molecules in diffuse clouds.

We present JWST images of NGC 6720 (the Ring Nebula), covering wavelengths from 1.6 μm to 25 μm. The bright shell is strongly fragmented with some 20 000 dense globules, bright in H2, with a characteristic diameter of 0.2 arcsec and density nH∼105–106cm−3. The shell contains a narrow ring of polycyclic aromatic hydrocarbon (PAH) emission. H2 is found throughout the shell and also in the halo. The central cavity is filled with high ionization gas and shows two linear structures seen in projection against the cavity. The central star is located 2 arcsec from the emission centroid of the cavity and shell. Linear features (‘spikes’) extend outward from the ring, pointing away from the central star. Around ten low-contrast, regularly spaced concentric arc-like features are present; they suggest orbital modulation by a low-mass companion with a period of about 280 yr. A previously known much wider companion is located at a projected separation of about 15 000 au; we show that it is an M2–M4 dwarf. NGC 6720 is therefore a triple star system. These features, including the multiplicity, are similar to those seen in the Southern Ring Nebula (NGC 3132) and may be a common aspect of such nebulae.