Characterising the Environment of Fullerene Formation

The bulk of the dust that is injected into the interstellar medium is formed via a complex chemistry in AGB circumstellar environments, which transforms the atomic gas into molecules and dust. To date, more than 60 individual molecular species of both inorganic and organic nature and a handful of dust minerals have been identified in these outflows. These environments are also thought to be the birthplace for large aromatic species such as polycyclic aromatic hydrocarbons and fullerenes. Because of their remarkable stability, fullerenes have been predicted to survive the harsh conditions of the insterstellar medium. However, targeted searches for the presence of fullerenes in various astrophysical environments were unsuccessful or not conclusive, until now. The Spitzer midIR spectrum of Tc1, a young planetary nebula with a low excitation central star and a high C/O abundance ratio, shows clear traces of C60 and C70. This indicates that when conditions are favorable, fullerenes are formed in large quantities. The midIR spectra allow us to quantify the abundance of carbon in the fullerenes, estimate their temperature, and detect them in the solid state in circumstellar environments, but to date we have little information on the circumstellar dust or the composition of the gas. We propose to use the farIR spectrum of Tc1 using the Herschel PACS spectrometer to study the energy balance and characterize the conditions in the circumstellar regions where fullerenes are formed. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]