Carbonaceous dust growth. Left panel: sublimation temperature, where the accretion and desorption rates on the surface of amorphous carbonaceous dust grains balance each other out, shown as a function of densities of C and H atoms in the gas. Right panel: effective accretion rates as a function of temperature on the surface of amorphous carbonaceous dust grains (effective number of accreting atoms per unit time per unit area), shown for different densities of C and H atoms in the gas. This is therefore the grain growth rate for the given conditions.