Interstellar amorphous carbon

Journal Article · Thu Oct 01 00:00:00 EDT 1987 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/185011· OSTI ID:5553623

Bussoletti, E; Colangeli, L; Orofino, V

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. 39 references.

• Research Organization: Istituto Universitario Navale, Naples, Italy; ESA, Space Science Department, Noordwijk, Netherlands; Lecce Universita, Italy
• OSTI ID: 5553623
• Journal Information: Astrophys. J.; (United States), Vol. 321
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC DUST
CHEMICAL COMPOSITION
INTERSTELLAR SPACE
ABSORPTION
ABUNDANCE
AMORPHOUS STATE
CARBON
GRAPHITE
MATHEMATICAL MODELS
ULTRAVIOLET RADIATION
DUSTS
ELECTROMAGNETIC RADIATION
ELEMENTAL MINERALS
ELEMENTS
MINERALS
NONMETALS
RADIATIONS
SPACE
640105* - Astrophysics & Cosmology- Galaxies