Infrared Study of Fullerene Planetary Nebulae

Abstract

We present a study of 16 PNe where fullerenes have been detected in their Spitzer spectra. This large sample of objects offers an unique opportunity to test conditions of fullerene formation and survival under different metallicity environments as we are analyzing five sources in our own Galaxy, four in the LMC, and seven in the SMC. Among the 16 PNe under study, we present the first detection of C60 (possibly also C70) fullerenes in the PN M 1-60 as well as of the unusual 6.6, 9.8, and 20 um features (possible planar C24) in the PN K 3-54. Although selection effects in the original samples of PNe observed with Spitzer may play a potentially significant role in the statistics, we find that the detection rate of fullerenes in C-rich PNe increases with decreasing metallicity (5% in the Galaxy, 20% in the LMC, and 44% in the SMC). CLOUDY photoionization modeling matches the observed IR fluxes with central stars that display a rather narrow range in effective temperature (30,000-45,000 K), suggesting a common evolutionary status of the objects and similar fullerene formation conditions. The observed C60 intensity ratios in the Galactic sources confirm our previous finding in the MCs that the fullerene emission is not excited by the UV radiation from the central star. CLOUDY models also show that line- and wind-blanketed model atmospheres can explain many of the observed [NeIII]/[NeII] ratios by photoionization suggesting that possibly the UV radiation from the central star, and not shocks, are triggering the decomposition of the circumstellar dust grains. With the data at hand, we suggest that the most likely explanation for the formation of fullerenes and graphene precursors in PNe is that these molecular species are built from the photo-chemical processing of a carbonaceous compound with a mixture of aromatic and aliphatic structures similar to that of HAC dust.

Accepted for publication in ApJ (43 pages, 11 figures, and 4 tables). Small changes to fit the proof-corrected article to be published in ApJ

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Cited by in corpus (43)

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• The detection of C60 in the well-characterized planetary nebula M1-11
• Far- and mid-infrared spectroscopy of complex organic matter of astrochemical interest: coal, heavy petroleum fractions, and asphaltenes
• The Mystery of Unidentified Infrared Emission Bands
• Searching for stable fullerenes in space with computational chemistry
• Infrared spectroscopy of fullerene C60/anthracene adducts
• Chemical abundances in Galactic planetary nebulae with Spitzer spectra
• The Role of Acetylene in the Chemical Evolution of Carbon Complexity
• Diffuse interstellar bands in fullerene planetary nebulae: the fullerenes - diffuse interstellar bands connection
• A Theoretical Study on the Vibrational Spectra of PAH Molecules with Aliphatic Sidegroups
• A search for diffuse bands in fullerene planetary nebulae: evidence of diffuse circumstellar bands
• C60 as a probe for astrophysical environments
• Search for Hydrogenated C${}_{60}$ (fulleranes) in Circumstellar Envelopes
• On Graphene in the Interstellar Medium
• Mapping the structural diversity of C60 carbon clusters and their infrared spectra
• Dust around R Coronae Borealis stars: II. Infrared emission features in a H-poor environment
• Modeling dust emission in PN IC 418
• A search for hydrogenated fullerenes in fullerene-containing planetary nebulae
• XSHOOTER spectroscopy of the enigmatic planetary nebula Lin49 in the Small Magellanic Cloud
• Detection of Cosmic Fullerenes in the Almahata Sitta Meteorite: Are They an Interstellar Heritage?
• How Much Graphene in Space?
• Synthesizing carbon nanotubes in space
• On the presence of metallofullerenes in fullerene-rich circumstellar envelopes
• Physical properties of the fullerene C60-containing planetary nebula SaSt 2-3
• Integrated molar absorptivity of mid- and far-infrared spectra of glycine and other selected amino acids
• GTC/CanariCam mid-IR imaging of the fullerene-rich Planetary Nebula IC 418: searching for the spatial distribution of fullerene-like molecules
• Chemical Abundances in the PN Wray16-423 in the Sagittarius Dwarf Spheroidal Galaxy: Constraining the Dust Composition
• Towards a reliable prediction of the infrared spectra of cosmic fullerenes and their derivatives in the JWST era
• On Carbon Nanotubes in the Interstellar Medium
• Hydrogenation of C${}_{24}$ carbon clusters : structural diversity and energetic properties
• 30-micron sources in galaxies with different metallicities
• Spectroscopy of fullerenes, fulleranes and PAHs in the UV, visible and near infrared spectral range
• Hydrogenated amorphous carbon grains as an alternative carrier of the 9$-$13$\mu$m plateau feature in the fullerene planetary nebula Tc 1
• Planetary Nebulae of the Large Magellanic Cloud II: the connection with the progenitors' properties
• Unusual Infrared Emission toward Sgr B2: Possible Planar C${}_{24}$
• Stability of C${}_{59}$ Knockout Fragments from Femtoseconds to Infinity
• Molecular studies of Planetary Nebulae
• On the formation of molecules and solid-state compounds from the AGB to the PN phases
• Outflowing Gas in the Planetary Nebula K 3-54
• Diffuse interstellar bands in (proto-) fullerene-rich environments