Normalized equilibrium charge fractions of helium (left) and hydrogen (right) in H₂O gas as a function of solar wind speed. The fraction of energetic neutral atoms (He⁰ and H⁰) is indicated as a gray line. Corresponding Maxwell-averaged solar wind distributions for an ion temperature T = 3.6 × 10⁶ K are plotted in blue in the 100–800 km s⁻¹ solar wind speed range. The grayed-out region above 800 km s⁻¹ shows where the temperature effects are not calculated because of fitting limitations.