Fabry-Perot spectra of Comet Halley emissions near 6300 Å were obtained at a spectral resolution of 0.2 (10 km sec-1), which was high enough to isolate cometary NH2 ((0,8,0) band) lines from cometary [OI]6300 emission and terrestial [OI]6300 and OH emissions. The NH2 spectra were used to obtain the NH2 production rate Q(NH2), which was compared with the H2O production rate QH2O), obtained from the [OI]6300 observations. Assuming that NH3 is the major source of NH2, then our NH2 emission measurements limit the abundance of NH3 relative to H2O. Our results depend on the value of the NH2 (0,8,0) band fluorescence efficiency factor gB. Using the M.F. A'Hearn (1982, In Comets (L. Wilkening, Ed.), Univ. of Arizona Press, Tucson) value for gB, we find that the NH3 abundance is about 0.1% that of H2O. If we use the recently revised value of gB calculated by S. Tegler and S. Wyckoff (1989, Astrophys. J., in press) the relative NH3 abundance increases to about 0.4%. In either case, our results indicate a low Comet Halley NH3 abundance relative to H2O.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science