The transonic solution of recombination-driven wind for hydrogen gas derived from the numerical solution to Equation (20) (see Appendix B for more details). The left panels correspond to a stellar mass of 1 M_⊙ and an entropy per baryon S = 36.0, while the right panels correspond to a stellar mass of 10 M_⊙ and an entropy per baryon S = 45.0. Both cases correspond to a Bernoulli parameter of ε = 0.6 U/μ. From top to bottom: the temperature (in units of K; blue horizontal dashed lines show T = 2T_ion), density (in units of g cm⁻³), and velocities (blue, orange, and green lines represent the velocity, the sound speed, and half of the escape velocity, respectively). All of the physical quantities are presented as a function of the radius (in units of au), from deep inside the hydrostatic region to outside the critical point. The recombination radii (at r_rec = 1.71 au and r_rec = 17.1 au, given by Equation (15)) and the critical points (at r_c = 2.58 au and r_c = 38.0 au) are marked with black dashed and dotted lines, respectively. The top axes present the local ionization fraction η, which decreases with the radius.