GRAPHITE GRAINS AND GRAPHITE CORE-ICE MANTLE GRAINS,
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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1965
- Accession Number
- AD0703626
Entities
People
- N. C. Wickramasinghe
Organizations
- California Institute of Technology