PAH Formation in O-rich Planetary Nebulae

Abstract

Polycyclic aromatic hydrocarbons (PAHs) have been observed in O-rich planetary nebulae towards the Galactic Bulge. This combination of oxygen-rich and carbon-rich material, known as dual-dust or mixed chemistry, is not expected to be seen around such objects. We recently proposed that PAHs could be formed from the photodissociation of CO in dense tori. In this work, using VISIR/VLT, we spatially resolved the emission of the PAH bands and ionised emission from the [SIV] line, confirming the presence of dense central tori in all the observed O-rich objects. Furthermore, we show that for most of the objects, PAHs are located at the outer edge of these dense/compact tori, while the ionised material is mostly present in the inner parts of these tori, consistent with our hypothesis for the formation of PAHs in these systems. The presence of a dense torus has been strongly associated with the action of a central binary star and, as such, the rich chemistry seen in these regions may also be related to the formation of exoplanets in post-common-envelope binary systems.

14, accepted for publication in the MNRAS Journal

References in corpus (7)

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• Spatially resolved kinematic observations of the planetary nebulae Hen 3-1333 and Hen 2-113
• Hidden IR structures in NGC 40: signpost of an ancient born-again event
• Planetary nebulae with Wolf-Rayet-type central stars -- II. Dissecting the compact planetary nebula M2-31 with GTC MEGARA
• JWST observations of the Ring Nebula (NGC 6720) -- II. PAH emission
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