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Photometric Observations of Recent Comets

Published online by Cambridge University Press:  22 February 2018

E. P Ney

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The first infrared observations of a comet were made by Becklin and Westphal (1966) who studied Comet Ikeya Seki (1965f) Their data at wavelengths of 1.6 to 10 microns revealed that this comet was a bright infrared object because of thermal radiation by dust grains in the coma. This is just another example of the importance of dust in infrared astronomy. The success of infrared is largely due to the extreme visibility of dust which reveals itself by reradiation in the infrared and by scattering or extinction in the visible. Optical opacities are χ = 104cm2/gm for one micron dust particle, for plasma free electrons, χ = 10-4cm2/gm for neutral molecules. By the time Bennett came along (1969i) infrared techniques were well developed, and the presence of an emission feature at 10 and 20 microns had been discovered in the infrared energy distributions of late type luminous supergiant stars (Woolf and Ney, 1969, for a summary see Ney (1972)).

Type
Part I
Information
International Astronomical Union Colloquium , Volume 25 , Issue Part1: The Study of Comets , 1976 , pp. 334 - 356
Copyright
Copyright © NASA 1976

References

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