Brightness profiles of C 3 and NH 3 in the atmosphere of P/Brorsen‐Metcalf

Spectroscopic observations of Comet P/Brorsen‐Metcalf were made on August 9–13, 1989. Spatial profiles extracted from long‐slit spectra were analyzed to determine the lifetimes of C 3 and NH 2 radicals and their parents, as well as the tailward acceleration of these radicals. In our investigations we used a Monte Carlo model. The average lifetime for C 3 has been found to be 6.3 × 10 4 s and that for the parent of C 3 to 6 × 10 3 s. The spatial profiles of C 3 were almost symmetric and we need only 0.1 cm s −2 as the tailward acceleration. According to our simulations, C 3 H 4 (allene) can be considered as the parent for C 3 . We obtained the average value 7.6 × 10 4 s for the lifetime of NH 2 and 1.1 × 10 4 s for the lifetime of the NH 2 parent. The tailward acceleration of NH 2 was not more than 0.1 cm s −2 . This result does not exceed the latest theoretical calculations of NH 2 and NH 3 lifetimes by a factor of 1.4. So, NH 3 may be considered as a parent for NH 2 in the atmosphere of P/Brorsen‐Metcalf.