UNIVERSAL PAH FRAGMENTATION: THE SEARCH FOR COMMON CARBON ANCESTORS

Helgi Rafn Hróðmarsson – Leiden Observatory (NL)

The chemical link between the diffuse interstellar medium and molecular clouds is not well characterized. This is in part because the century old mystery of the Diffuse Interstellar Bands (DIBs) is still unsolved, as it could hold the keys to unlocking which are the most important molecules capable of surviving in the diffuse interstellar medium for aeons. By studying the radiation-induced fragmentation of several PAH species of different symmetry and different sizes, this work shows that PAHs appear to follow very similar fragmentation pathways, giving rise to ionized magic number carbon clusters. These could be ideal candidates as products of PAH destruction in PDRs and other astrophysical regions that ungergo significant energetic processing. If this scenario is taken to the extreme, these clusters might survive in the diffuse interstellar medium for a long enough period to form the first chemical seeds of molecular clouds – becoming the common carbon ancestors of stars, planets, and life.