The role and diversity of fullerenes in space

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The Universe contains a wide variety of carbonaceous molecules and dust grains that are first formed around red giant stars when they eject their outer envelopes into the interstellar medium. This carbonaceous material is further processed, first by intense UV radiation when the hot stellar core is exposed and lights up the surrounding material as a planetary nebula; later by energetic radiation and particles in the interstellar medium. Only the most stable species, such as buckyballs, can survive the rigors of space. Eventually, this material collects in the form of giant molecular clouds in which the next generation of stars and planets are formed seeded thus with the molecules and dust ejected by red giant stars. Astronomers can study distant molecules and dust grains because each species imprints a specific color pattern (“spectral fingerprint”) in starlight. Recently, my research team discovered the unmistakable spectral fingerprint of buckyballs in observations of a planetary nebula. Buckyballs (also known as buckminsterfullerene or C60) are microscopic particles composed of 60 carbon atoms, shaped like a soccer ball. Very recently, it has been proven that charged buckyballs (C60+) are responsible for four of the “diffuse interstellar bands” (DIBs), a set of hundreds of mysterious spectral fingerprints that we see whenever starlight is dimmed by intervening clouds of interstellar gas and dust. This is the first and only time that any of these prominent interstellar fingerprints has been unambiguously identified with a specific molecule, demonstrating that buckyballs are ubiquitous and abundant in our galaxy. Although we have learned much about cosmic buckyballs in recent years, we do not yet understand how they form, what other related molecular structures form at the same time, or what other stable species is responsible for the rest of the DIBs. Answering those questions is essential for our understanding of the inventory of carbonaceous materials in the Universe our cosmic roots. I propose a research program that will determine the precise conditions and chemical pathways that lead to the formation of buckyballs and other carbonaceous materials in space. I will do this by analyzing tailored, state-of-the-art astronomical observations, and by developing detailed astrochemical models for the formation of carbonaceous species in planetary nebulae. I will also produce the largest and most detailed DIB catalog ever, to find any DIBs that are related to C60, and to turn the DIBs into powerful probes of their environment. This research will reveal some of the hardiest carbonaceous materials in the Universe and elucidate the currently unknown pathways to form them. These processes are important to materials science researchers and the manufacturing industry. It will also turn several young researchers into data scientists with skills that are highly desired in Canadian industry.