Narrowband Photometry of Comet Austin 1990V

Abstract

The results of photoelectric photometry with the narrowband CN, C 3, C 2, blue continuum, and ultraviolet continuum IHW interference filters are presented. The observations were carried out with a set of diaphragms of different radii. Vectorial Monte Carlo modeling of the cometary coma was used for the determination of production rates of the radicals, the parent and daughter lifetimes, and the daugher ejection velocities from the parents. The CN and C 2 parent lifetimes (at 1.0 AU) were 2.7 ± 1.3 × 10 4 and 2.3 ± 0.6 × 10 4 sec, respectively, and the lifetimes of CN, C 3, and C 2 molecules were 2.1 ± 3.0 × 10 5, 1.8 ± 2.0 × 10 5, and 1.1 ± 0.4 × 10 5 sec (at 1.0 AU), respectively. The daughter ejection velocities from parents were 2.6 ± 1.2 km sec -1 for the CN and 0.1 ± 0.8 km sec -1 for the C 2 molecule. The dependence on heliocentric distance of the molecules and dust production rates in the range of 0.7 ÷ 1.0 AU was described by the power law function r -n h . The power index was 2.97 ± 0.11 for CN, 2.34 ± 0.55 for C 3, 2.44 ± 0.17 for C 2, and 3.44 ± 0.51 for dust. Relative abundances of CN and C 3 for Comet Austin at 1.0 AU postperihelion were similar to the "normal" ones with some enrichment of the C 2 molecule.