- Published on 13 May 2015
In section 6. Interstellar and circumstellar matter
Top-down formation of fullerenes in the interstellar medium
It is fairly well established now that Buckminsterfullerene, or C60, is present in both reflection nebulae and circumstellar shells. Polycyclic aromatic hydrocarbons (PAHs) with probably 50-100 C atoms are also found in such regions, and it is natural to think that there is a connection between the two. Could one be made from the other? Berné and collaborators study the particular example of the possible transformation of a PAH C66H20 into C60. They conclude that, as depicted in the figure, this must first involve dehydrogenation, followed by a folding process and finally shrinkage (with loss of C2 units) to the familiar football-like shape of fullerene. They find that for the conditions of the reflection nebula NGC 7023, this could reasonably take place in about 10^5 years, which seems reasonable. The amount of fullerene formed seems also consistent with that observed, and thus this is the outline of a model that can be tested with more detailed studies.