The Theory of Cosmic Grains

1. Front Matter

   Pages i-ix

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2. Introduction

   • F. Hoyle, N. C. Wickramasinghe

   Pages 1-14

3. Electromagnetic Properties of Small Particles

   • F. Hoyle, N. C. Wickramasinghe

   Pages 15-46

4. Interstellar Extinction and Polarisation

   • F. Hoyle, N. C. Wickramasinghe

   Pages 47-71

5. Reflection Nebulae and the Diffuse Galactic Light

   • F. Hoyle, N. C. Wickramasinghe

   Pages 72-93

6. Interactions Between Dust, Gas and Radiation

   • F. Hoyle, N. C. Wickramasinghe

   Pages 94-127

7. Inorganic Theories of Grain Formation

   • F. Hoyle, N. C. Wickramasinghe

   Pages 128-151

8. The Organic Grain Model

   • F. Hoyle, N. C. Wickramasinghe

   Pages 152-177

9. Models of the Extinction and Polarisation of Starlight

   • F. Hoyle, N. C. Wickramasinghe

   Pages 178-215

10. Spectroscopic Identifications

    • F. Hoyle, N. C. Wickramasinghe

    Pages 216-275

11. Dust in External Galaxies

    • F. Hoyle, N. C. Wickramasinghe

    Pages 276-292

12. Back Matter

    Pages 293-307

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Light scattering and absorption by small homogeneous particles can be worked-out exactly for spheres and infinite cylinders. Homogeneous particles of irregular shapes, when averaged with respect to rotation, have effects that can in general be well-approximated by reference to results for these two idealised cases. Likewise, small inhomogeneous particles have effects similar to homogeneous particles of the same average refractive index. Thus most problems can be solved to a satisfactory approximation by reference to the exact solutions for spheres and cylinders, which are fully stated here in the early part of the book. The sum of scattering and absorption, the extinction, is too large to be explained by inorganic materials, provided element abundances in the interstellar medium are not appreciably greater than solar, H 0 and NH3 being essentially excluded in the 2 general medium, otherwise very strong absorptions near 3p,m would be observed which they are not. A well-marked extinction maximum in the ultraviolet near 2200A has also not been explained satisfactorily by inorganic materials. Accurately formed graphite spheres with radii close to O.02p,m could conceivably provide an explanation of this ultraviolet feature but no convincing laboratory preparation of such spheres has ever been achieved.

• Galaxy
• galaxies
• stellar

• Bournemouth, UK

  F. Hoyle

• School of Mathematics, University of Wales, Cardiff, UK

  N. C. Wickramasinghe

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