Fractional abundances of some daughter species as a function of radius, calculated using different initial fractions of CH₄ (panels a) and b)), atomic S (panel c)), and N₂ (panel d)), in addition to various cosmic-ray rates. In panel a): the arrows indicate the upper limits of C₂H (red) and CH₃OH (green) deduced in the observational work of Marvel (2005) where the peak radii of these species was assumed to be 1.5 × 10¹⁶ cm. In panel b): χ is the scaling factor of the cosmic-ray ionization rate and the star indicates the observational result from Pulliam et al. (2011).