Invited Talk

Fullerenes in Circumstellar and Interstellar Environments

¹Jan Cami, ²Jeronimo Bernard-Salas, ¹Els Peeters, ¹Elisabetta Micelotta, ²Anthony Jones, ¹Giovanni Fanchini (¹The University of Western Ontario, ²Institut d'Astrophysique Spatiale)

We recently discovered and identified the spectral signatures of the fullerene species C60 and C70 in observations of a young planetary nebula obtained with the Spitzer Space Telescope. Fullerenes have since been confirmed in a wide variety of astronomical objects -- in young stellar objects and evolved stars as well as in the interstellar medium -- where they represent typically 0.3% of the cosmic carbon. They are the largest molecules known to exist in space to date, and are the first identified large aromatic species in astrophysical environments. Since the properties of fullerenes (and especially C60) have been studied in great detail in laboratories on Earth, these detections offer a great potential to use the fullerene spectral features as diagnostic probes for the environment in which they reside. In turn, such studies could provide a great deal of insight into the properties and evolution of the much larger reservoir of large aromatic molecules in space.

In this talk, I will give an overview of what we have learned so far from observational analyses, theoretical models and laboratory efforts on astrophysical fullerenes. I will highlight some of the surprising and puzzling aspects that have challenged our understanding of the physics and chemistry involved, in particular about the formation and excitation of fullerenes in space. I will also discuss how fullerenes compare to other large aromatics such as polycyclic aromatic hydrocarbon (PAHs).

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