JWST observations of the Ring Nebula (NGC 6720): II. PAH emission

Clark, Nicholas, Peeters, Els, Cox, Nick L. J., Cami, Jan, Barlow, Michael J., Kavanagh, Patrick J., Van de Steene, Griet, Matsuura, Mikako ORCID: https://orcid.org/0000-0002-5529-5593, Zijlstra, Albert, Aleman, Isabel, Bernard-Salas, Jeronimo, Dinerstein, Harriet L., Justyanont, Kay, Kaplan, Kyle F., Manchado, Arturo, Sahai, Raghvendra, van Hoof, Peter, Volk, Kevin and Wesson, Roger 2025. JWST observations of the Ring Nebula (NGC 6720): II. PAH emission. Monthly Notices of the Royal Astronomical Society , staf826. 10.1093/mnras/staf826

PDF - Accepted Post-Print Version Available under License Creative Commons Attribution. Download (1MB)

Abstract

Polycyclic aromatic hydrocarbons (PAHs) and carbonaceous dust have been observed in clumpy circumstellar environments, yet their formation and evolutionary pathways in such environments remain elusive. We aim to characterize the PAH emission in a clumpy planetary nebula to decipher their formation and evolution pathways. We obtained JWST NIRSpec and MIRI IFU spectroscopic observations of two individual knots in the Ring Nebula (NGC 6720), a clumpy planetary nebula, and determine the PAH spectral characteristics. We detect the 3.3 and 11.2 μm PAH emission bands in both knots but do not detect PAH emission in the 6-9 μm range. We supplement our data with Spitzer/IRS SL1 (Short-Low) and SL2 data, containing 11.2, weak 6.2, and weak 7.7 μm PAH emission bands. The JWST data confirm the unusual profile of the 11.2 μm band, which is very broad and redshifted with respect to typical 11.2 μm PAH profiles. We estimate the PAH population to be largely neutral. The relative integrated surface brightness of the 3.3 and 11.2 μm bands indicates the presence of small-sized PAHs, consisting of 35±6 carbon atoms. We find that the PAH emission is concentrated outside of the clumps, in the inter-clump medium, and confirm the existence of enhanced PAH emission in a narrow “PAH ring” centered on the central star. This morphology suggests that PAHs formed during the Ring Nebula’s Asymptotic Giant Branch (AGB) phase, in the central star’s dust-driven wind.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Schools > Physics and Astronomy
Publisher:	Oxford University Press
ISSN:	0035-8711
Date of First Compliant Deposit:	22 May 2025
Date of Acceptance:	12 May 2025
Last Modified:	03 Jun 2025 09:45
URI:	https://orca.cardiff.ac.uk/id/eprint/178446

Actions (repository staff only)

Edit Item