Interstellar amorphous carbon

Abstract

view Abstract Citations (28) References (36) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Interstellar Amorphous Carbon Bussoletti, E. ; Colangeli, L. ; Orofino, V. Abstract Amorphous carbon grains are discussed as possible candidates for cosmic dust. Particles obtained in the laboratory do not correctly reproduce the portion of the interstellar extinction curve commonly attributed to graphite. Amorphous carbon grains with a 40-A mean radius respect the carbon cosmic abundance constraints; however, they cannot explain the interstellar UV extinction curve because they show a peak at 2350 A and give a contribution which is too high to the visual extinction. The present experimental results have been used to construct an 'interstellar amorphous carbon' (IAC) whose properties are able to resolve the above-mentioned difficulties. Extrapolations of the laboratory data show that a size distribution with a 10-A average radius has an extinction efficiency with the peak at the right position, satisfactorily matching in shape the interstellar hump. The peak to visual extinction ratio, Gamma = 3.8, justifies the existence of other dielectric materials which may account for the observed linear polarization. IAC requires no more than 18 percent of the available carbon to produce the hump. The results are discussed in terms of evolution of carbon grains in space showing that, in this picture, the presence of graphite is no longer necessary to account for most of the solid carbonaceous material. Publication: The Astrophysical Journal Pub Date: October 1987 DOI: 10.1086/185011 Bibcode: 1987ApJ...321L..87B Keywords: Amorphous Materials; Carbon; Cosmic Dust; Interstellar Matter; Abundance; Astronomical Models; Graphite; Interstellar Extinction; Microcrystals; Astrophysics; INTERSTELLAR: GRAINS full text sources ADS |