Journal Article

Modelling anomalous extinction using nanodiamonds

Rakesh K. Rai and Shantanu Rastogi

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 423, issue 3, pages 2941-2948
Published in print July 2012 | ISSN: 0035-8711
Published online June 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.21109.x
Modelling anomalous extinction using nanodiamonds

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The modelling of extinction along anomalous/non-Cardelli, Clayton & Mathis sightlines, which are characterized by a broad 217.5-nm bump and steep far-ultraviolet (FUV) rise, is reported. The extinction along these sightlines, namely HD 210121, HD 204827, HD 29647 and HD 62542, is difficult to reproduce using standard silicate and graphite grains. A very good match with the observed extinction is obtained by considering a nanodiamond component as part of the carbonaceous matter. Most of these sightlines are rich in carbon and are invariably backed by a young hot stellar object. Nanodiamond is taken as a core within amorphous carbon and graphite. These core–mantle particles, taken as additional components along with graphite and silicates, lead to a reduction in the silicate requirement. The abundance of carbonaceous matter is not affected, as a very small fraction of nanodiamond is required. Extinction along sightlines that show steep FUV is also reported, demonstrating the importance of the nanodiamond component in all such regions.

Keywords: dust, extinction; ISM: general

Journal Article.  4186 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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