Studying the fullerene nest: JWST observations of the planetary nebula Tc 1. II. A spectroscopic and spatial study of the C₆₀ and C₇₀ emission

M.M. Giese (Univ. Western Ontario), J. Cami (Univ. Western Ontario), S. Van Schuylenbergh (Univ. Western Ontario), E. Peeters (Univ. Western Ontario), C. Bhatt (Univ. Western Ontario), D. Van De Putte (Univ. Western Ontario), C. Baerts (Univ. Western Ontario), M.J. Barlow (Univ. Coll. London), J. Bernard-Salas (ACRI-ST, INCLASS Common Lab.), A. Candian (Univ. Amsterdam), P.B. Changala (Univ. Colorado), N.L.J. Cox (ACRI-ST), H.L. Dinerstein (Univ. Texas) V.J. Esposito (Chapman Univ.), D.A. Garcia-Hernandez (Inst. Astrof. Canarias, Univ. La Laguna), M.A. Gomez-Munoz (Univ. Barcelona), K. Justtanont (Chalmers Univ. of Tech), K.E. Kraemer (Boston Coll.), E. Lagadec (Obs. Cote d'Azur), A. Manchado (Inst. Astrof. Canarias, Univ. La Laguna), A. Monreal Ibero (Leiden Univ.), R. Sahai (JPL), A. Sidhu (Univ. Western Ontario), G.C. Sloan (STScI, UNC), N.C. Sterling (Univ. W. Georgia), A.G.G.M. Tielens (Univ. Maryland), J.R. Walsh (ESO), R. Wesson (Univ. Coll. London, Cardiff Univ.), J.C. Whitman (Univ. W. Georgia), A. Zijlstra (Univ. Manchester), L. Finazzi (Radboud Univ.), J. Martens (Radboud Univ.), G. Berden (Radboud Univ.), J. Oomens (Radboud Univ.)

2026, ApJ, submitted

We present a detailed analysis of the fullerene emission bands in JWST MIRI/MRS observations of the planetary nebula Tc 1. The observations reveal the emission features due to neutral C₆₀ and C₇₀ in unprecedented detail. The combined fullerene emission represents ~2.6% of the total infrared output, suggesting that ~0.6% of the carbon budget is locked up in fullerenes. We find no clear evidence for C₆₀⁺, C₇₀⁺ or C₆₀^- in the spectrum. The high spectral resolution allows us to separate the fullerene bands from atomic emission lines for the first time, allowing for a much better characterization of the band profiles and yielding more accurate band ratios than previous observations. We see no spatial variation in the individual C₆₀ and C₇₀ band profile shapes across all pixels. The 17.4 and 18.9 µm C₆₀ bands show clear resolved ro-vibrational structure in their profiles, and similar structured emission is seen in the 12.5, 14.8, 17.7, and 21.8 µm C₇₀ bands, further establishing that all emitting fullerene molecules are in the gas phase. We report a higher 7.0/18.9 µm C₆₀ band ratio of ~1.4-1.9 than the previously reported in Tc 1 of ~1.3. We note that all bands, except the 8.5 µm band, contain a significant contribution from C₇₀, complicating the analysis. The fullerene emission is spatially concentrated in a thin, asymmetric shell at a radius of 5-6" from the central star. The shell lies at the outer edge of the core of the nebula, which was ejected in a single, brief episode ≳4,000 years ago.

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