Narrowband Photometry of Comet P/Halley: Variation with Heliocentric Distance, Season, and Solar Phase Angle

doi:10.1006/icar.1997.5902

Icarus

Volume 132, Issue 2, April 1998, Pages 397-417

https://doi.org/10.1006/icar.1997.5902 Get rights and content

Abstract

Narrowband filter photometry of Comet P/Halley from 109 nights in 1985, 1986, and 1987 is analyzed to discern the comet's variation in activity with changing heliocentric distance and season. The scattering phase function of dust in the coma is also investigated. Asymmetry about perihelion in the production of gas and dust is confirmed. However, we find the asymmetry to be significantly less for water than for the trace species and for dust grains. The relative abundances of CN, C₂, and C₃remain essentially constant with respect to each other throughout the apparition, but change markedly with respect to water. The behavior of NH also more closely tracks that of the carbon-based species than that of water. These phenomena are most readily understood in terms of seasonal effects on a compositionally variegated nucleus. However, this explanation may not work if Halley's nucleus is in a complex long-axis-mode rotational state as many believe to be the case. Observations of Halley's continuum reveal a substantial change near perihelion in the average radial distribution of dust in the inner coma, with the dust displaying a canonical 1/ρ fall-off after perihelion but a much steeper decrease with distance from the nucleus during 1985. The phase function of the dust shows pronounced curvature over the observed range of values (1.5° to 66°). The slope is 0.045 mag/degree near 0° phase angle but becomes nearly flat at angles greater than about 30°. The peak of the phase function at 0° is 2.9 times that at the minimum near 50°, compared with the 2× enhancement typically measured for the zodiacal light.

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^☆: Z. Sekanina

^f1: [email protected]

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Regular ArticleNarrowband Photometry of Comet P/Halley: Variation with Heliocentric Distance, Season, and Solar Phase Angle☆

Abstract

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Photometry and polarimetry network

The Comet Halley Archive Summary Volume

Cyanogen jets in Comet Halley

Nature

Comet Bowell 1980b

Astron. J.

Volatiles in cometary grains

Cometary grains

Astron. J.

Retrieving the coma gas expansion velocity in P/Halley, Wilson (1987 VII) and several other comets from the 18-cm OH line shapes

Astron. Astrophys.

A model for the coma of Comet Halley, based on the Astron ultraviolet spectrophotometry

Sov. Astron. Lett.

Pre- and post-perihelion Astron ultraviolet spectrophotometry of Comet Halley: A comparative analysis

Sov. Astron. Lett.

Pre-perihelion photometry of P/Halley (1982i) at Catania (Italy) Observatory

Astron. Astrophys.

Proceedings of the 20th ESLAB Symposium on the Exploration of Halley's Comet

Some results of the narrow-band photometry of Comet Halley (1986 III)

Astrophys. J.

Spectrophotometric observations of Comet Halley

20th ESLAB Symposium on the Exploration of Halley's Comet

The fragmentation of dust in the innermost comae of comets: Possible evidence from ground-based images

Astron. J.

The OH distribution in cometary atmospheres: A collisional Monte Carlo model for heavy species

Astrophys. J.

Vaporization of cometary nuclei: Light curves and lifetimes

Moon Planets

Spectrophotometric observations of Comet Halley during the 1984–86 apparition

Mon. Not. R. Astr. Soc.

The Comet Halley dust and gas environment

Space Sci. Rev.

IUE observations of Comet P/Halley: Evolution of the ultraviolet spectrum between September 1985 and July 1986

Astron. Astrophys.

The abundance of ammonia in Comet P/Halley derived from ultraviolet spectrophotometry of NH by ASTRON and IUE

Astrophys. J.

The trend of production rates with heliocentric distance for Comet P/Halley

Astrophys. J.

The production rate and spatial distribution of H2

Astrophys. J.

Narrow-band photometry of Comet P/Halley—OH and H2

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Regular Article
Narrowband Photometry of Comet P/Halley: Variation with Heliocentric Distance, Season, and Solar Phase Angle☆

The production rate and spatial distribution of H₂

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