Bibcode
Iglesias-Groth, Susana
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 368, Issue 4, pp. 1925-1930.
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6
2006
Citations
44
Refereed citations
35
Description
We study the rotation rates and electric dipole emission of hydrogenated
icosahedral fullerenes under the physical conditions of the dark cloud
(DC) LDN 1622. The abundance of fullerenes is estimated by fitting
theoretical photoabsorption spectra to the characteristics of the
ultraviolet (UV) bump extinction in DCs. The UV bump appears to be well
reproduced by a mixture of fullerenes following a size-distribution
power law, which gives progressively lower abundances as the radius of
the fullerene increases. We infer abundances of the order of 0.2 ×
10-6n(H 2) for C60. A significant
fraction of these molecules are expected to be hydrogenated. We compute
the electric dipole rotational emission from these fullerene hydrides,
taking into account rotational excitation and damping processes. The
recent detection of anomalous microwave emission (5-60 GHz) in LDN 1622
by Casassus et al. can be explained as the result of electric dipole
radiation from hydrogenated fullerenes. The bulk of the emission (10-30
GHz) appears to be associated with 60-80 carbon atom fulleranes with a
degree of hydrogenation of C:H ~ 3:1. A small contribution (~10 per
cent) of these molecules residing in the surrounding cold neutral medium
and/or photodissociation region of the cloud is required to fit the
high-frequency tail (40-60 GHz) of the emission.