Annealed HAC mantles in diffuse dust clouds

Details Annealed HAC mantles in diffuse dust clouds Annealed HAC mantles in diffuse dust clouds

Feb 1991

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1991mnras.248..439s&link_type=abstract

Monthly Notices of the Royal Astronomical Society (ISSN 0035-8711), vol. 248, Feb. 1, 1991, p. 439-443.

Other

11

Carbon, Cosmic Dust, Interstellar Matter, Molecular Clouds, Silicates, Absorption Spectra, Amorphous Materials, Hydrogenation, Infrared Spectra, Optical Thickness

Scientific paper

Carbon grains in the diffuse cloud medium consist of HAC mantles accreted on to silicate-oxide cores. It is shown that laboratory data support a model in which the ratio of sp3 to sp2 hybridized carbon atoms is a function of the mantle temperature and varies from one interstellar cloud to another. Cold mantles are characterized by a high proportion of sp3 diamond-like carbon and a 3.4-micron absorption band in the spectrum of highly reddened field stars. It is shown that the HAC model agrees with observations of the 3.4-micron absorption feature, provided that cold mantles have no more than 30 percent of the carbon atoms chemisorbed to hydrogen. In diffuse interstellar clouds showing low dust obscuration, mantle heating by ultraviolet starlight shifts the bonding structure from diamond-like (sp3) to graphitic (sp2) carbon. The hot HAC mantles would then show a ubiquitous 3.3-micron emission feature in the diffuse cloud medium and no 3.4-micron feature at all. Thus, variations of the sp3/sp2 ratio with mantle temperature can explain why the 3.4-micron band frequently appears in absorption, whereas the 3.3-micron band always appears in emission.

Affiliated with

Also associated with

No associations

Rating

Annealed HAC mantles in diffuse dust clouds does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Annealed HAC mantles in diffuse dust clouds, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Annealed HAC mantles in diffuse dust clouds will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1318172