doi:10.1038/nindia.2012.107 Published online 27 July 2012
Relying on computer-based models, researchers have discovered that nanodiamonds in dark dust clouds could play vital roles in absorbing starlight in the Milky Way. Located a few hundred to several thousand light years away, such nanodiamonds form the core of graphite mantle and amorphous carbon (AMC) and absorb far-ultraviolet light and emit red light.
This study could help scientists understand diamond formation in space and dust formation in the dust cloud regions between stars.
Previous studies have not explored the potential role of nanodiamonds in the extinction of far-ultraviolet light in dense dark clouds around B-type stars. To accomplish this task, the researchers considered nanodiamond (ND) cores in graphite mantle and AMC, including only silicate and graphite dust-grain models. They considered a distribution of different-sized grains, with the largest ND core size being 5 nm in graphite and 10 nm in AMC, and assumed that the grains inhabit dense dark clouds near B-type stars.
Using data from astronomical observations, the researchers found that the material in protoplanetary discs inherited from such dust clouds will contain ND mainly as an ND–AMC component. The AMC mantle in the inner regions can be shredded by heating, shocks or grain shattering. This may leave the nanodiamonds with dangling hydrogen atoms that can exhibit specific emission features.
"Besides contributing to emission features, the presence of ND-type grains in dark clouds will affect the cloud chemistry," says lead researcher Shantanu Rastogi from Gorakhpur University, India.