Accession Number : AD0703626

Title :   GRAPHITE GRAINS AND GRAPHITE CORE-ICE MANTLE GRAINS,

Corporate Author : CALIFORNIA INST OF TECH PASADENA

Personal Author(s) : Wickramasinghe,N. C.

Report Date : 1965

Pagination or Media Count : 26

Abstract : The present situation concerning graphite interstellar grains is reviewed. Mie computations extending into the far ultraviolet are now available for experimentally determined values of the complex refractive index. Small graphite particles produce a sharp quenching effect in the ultraviolet, the extinction curves rising to a maximum at about 2200 A. The possibility that graphite particles ejected from stars may grow ice mantles in cloud conditions has been considered. Such growth is, however, restricted, mainly due to: (1) the effect of cloud collisions leading to the stripping of mantles by a sputtering process, and, (2) the limited supply of 0 atoms available to form mantles. A steady-state size distribution of ice mantles around graphite cores is obtained on the assumption that the processes of growth and destruction have reached equilibrium. Extinction computations have also been performed for graphite core-ice mantle grains. The qualitative features of the recent extinction measurements in the rocket ultraviolet are also easily explained in terms of absorption by small graphite grains, or graphite core-ice mantle grains. (Author)

Descriptors :   (*INTERSTELLAR MATTER, GRAPHITE), ULTRAVIOLET RADIATION, REFRACTIVE INDEX, ICE, PARTICLE SIZE, CRYSTAL STRUCTURE, CRYSTAL GROWTH, ABSORPTION, MATHEMATICAL MODELS

Subject Categories : Astrophysics

Distribution Statement : APPROVED FOR PUBLIC RELEASE