Observations of Comet Crommelin. V - Anomalous hydrogen source

Abstract

Lyman-alpha intensities measured by IUE at various positions in the coma of Comet Crommelin are interpreted on the basis of H2O model calculations. However, the H-production on dates in March and April 1984 was significantly higher than implied by OH measurements by IUE and from the ground. Simultaneous data from the two apertures on March 30 exclude a high geocoronal contribution. The inferred H-source did not follow the systematic steep decrease in OH, nor that in CN, etc. (power indexes greater than about 3.5), which behavior tallies with limited evidence from previous comets. A strong source of H-atoms separate from any H2O/OH is inferred, for which hydrocarbons or OH-depleted organics are possible candidates.