SUMMARY
The effect of pair ions on the formation and propagation characteristics of Ion-Acoustic (IA) shock waves in a six-component cometary plasma composed of two hot and one colder electron component, hot ions, and heavier pair ions is studied. The colder and one hotter component of electrons together with the lighter hydrogen ions are modelled by kappa distributions. The other hotter electron component is described by a q-nonextensive distribution. The KdVB equation is derived for the system and its solution plotted for different kappa values, oxygen ion densities, kinematic viscosities as well as the temperature ratios of ions. In the aforesaid plasma, the shock wave exhibits a transition towards solitary structure. It is found that the strength of shock profile decreases with an increase in both temperatures of the positively charged oxygen ions and negatively charged oxygen ion densities. However, the strength of the shock wave decreases with a decrease of positively charged oxygen ion densities.