Showing papers by "N. C. Wickramasinghe published in 1993"
TL;DR: In this article, the development of infrared emission from Supernova 1987A is modelled on the basis of a mixture of millimetre long iron whiskers of radius 0.01 µm, and spherical iron grains of the same radius.
Abstract: The development of infrared emission from Supernova 1987A is modelled on the basis of a mixture of millimetre long iron whiskers of radius 0.01 µm, and spherical iron grains of the same radius. The total mass of iron grains involved is less than 10−5M⊙.
12 citations
TL;DR: In this paper, it was shown that ~ 102M⊙ of iron in the form of long slender whiskers, expelled from supernovae, can explain an observed deficit of line emission in the 157.7µm C II line and in the 205µ m N II line from the galactic centre region.
Abstract: It is shown that ~ 102M⊙ of iron in the form of long slender whiskers, expelled from supernovae, can explain an observed deficit of line emission in the 157.7µm C II line and in the 205µm N II line from the galactic centre region.
2 citations
TL;DR: In this paper, the optical constants of impure meteoritic microdiamonds were used to calculate the 3.4µm absorption profile of nanometre-sized micro diamonds.
Abstract: The optical constants of impure meteoritic microdiamonds are used to calculate the 3.4µm absorption profile of nanometre-sized microdiamonds, and microdiamonds with water-ice coatings. It is shown that the 3.4µm feature observed in protostellar sources cannot be easily explained on the basis of such models.
1 citations
TL;DR: In this paper, an early stage in the aggregation of the inner planets and comets was detected in the Paleozoic-Mesozoic bedded chert, which is assumed to be of extraterrestrial origin and comprised of clusters of iron needles.
Abstract: Microspherules in Paleozoic-Mesozoic bedded chert, presumed to be of extraterrestrial origin and comprised of clusters of iron needles,may represent an early stage in the aggregation of the inner planets. A fraction of the constituent iron needles will be expected to be carried along with expanding gas to the periphery of the solar nebula where the outer planets and comets condensed. A substantial fraction of iron needles would escape into interstellar space and add to the population of interstellar grains. Iron needles could contribute substantially to interstellar polarization and to the infrared opacity of the interstellar medium.
TL;DR: In this article, it was shown that suitably defined Guttler analogues can satisfactorily represent the optical cross-sections of aggregates of very small particles that result from mutual collisions and sticking.
Abstract: We show that suitably defined Guttler (core-mantle) analogues can satisfactorily represent the optical cross-sections of aggregates of very small particles that result from mutual collisions and sticking. Earlier calculations using the discrete dipole approximation are seen to be in good agreement with Guttler analogue calculations, particularly in the case of the so-called Ballistic Particle-Cluster Aggregates (BPCA).