Are C-60 Molecules Detectable In Circumstellar Shells Of R Coronae Borealis Stars?

Garcia-Hernandez, D. Anibal
Rao, N. Kameswara
Lambert, David L.
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The hydrogen-poor, helium-rich, and carbon-rich character of the gas around R Coronae Borealis (RCB) stars has been suggested to be a site for formation of C-60 molecules. This suggestion is not supported by observations reported here showing that infrared transitions of C-60 are not seen in a large sample of RCB stars observed with the Infrared Spectrograph on the Spitzer Space Telescope. The infrared C-60 transitions are seen, however, in emission and blended with polycyclic aromatic hydrocarbon (PAH) features in spectra of DY Cen and possibly also of V854 Cen, the two least hydrogen-deficient (hydrogen deficiency of only similar to 10-100) RCB stars. The speculation is offered that C-60 (and the PAHs) in the moderately H-deficient circumstellar envelopes may be formed by the decomposition of hydrogenated amorphous carbon but fullerene formation is inefficient in the highly H-deficient environments of most RCBs.

Garc�a-Hern�ndez, D. A., N. Kameswara Rao, and D. L. Lambert. "Are C60 molecules detectable in circumstellar shells of R Coronae Borealis stars?." The Astrophysical Journal, Vol., 729, No. 2 (Mar., 2011): 126.