Spectrophotometry of Comet p/ Halley at Wavelengths 275-NM to 710-NM from VEGA-2
Abstract
Spectrophotometric observations of the inner coma of comet Halley in the range 275-710 nm were conducted from Vega2 on March 8, 9, 10, 11, 1986. During the encounter session, when the impact parameter was minimum, p = 120 km, the gaseous emissions were still present, superimposed on an intense continuum. In the inner coma, C2 and C3 emissions steadily increase when the impact parameter decreases. The emissions of OH at 309 nm and CN in its band head at 388 nm show a plateau between 1500 and 600 km. The decrease in OH emission when the impact parameter is less than 500 km is interpreted in terms of high optical thickness of water vapor at Lyman-alpha. Pixel-to-pixel ratios of spectra show that the color of dust continuum presents small fluctuations which might be produced by a discontinuous emission of icy grains.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 1987
- Bibcode:
- 1987A&A...187..551M