Distribution of neutral (light blue dots; left panel) and ionized (light red dots; right panel) magnesium atoms within ±0.5 R_p of the orbital plane for the best-fit simulation in the G-scenario. Magnesium atoms that escape at the exobase level (R_exo = 3 R_p; striped blue disk) are accelerated away from the star by radiation pressure (the star is along the vertical direction toward the top of the plot). They remain neutral up to the recombination altitude (R_rec = 3.9 R_p; dashed blue circle) and keep a high probability to stay in this state until they reach the equilibrium altitude (R_eq = 13.4 R_p; dashed black circle), beyond which ionized magnesium particles do not recombine efficiently anymore. Because of the planet shadow and shielding from the main atmosphere, the inner part of the cometary tail is empty of radiation-pressure accelerated particles.