Spatial x (in units of plasma length scale λ = c_sτ) expansion profiles of (a, b) density, (c, d) velocity, and (e) electric potential for both oxygen (right) and hydrogen (left), respectively, after different time intervals t, including 1 (black), 5 (red-dashed), 10 (blue-dotted), 50 (orange dash-dotted). (f) Time profile (in units of the plasma timescale τ = 1 s) of the oxygen density at different values of distance x: 1 (black), 2 (red-dashed), 3 (blue-dotted), and 4 (orange dash-dotted). Here, the solar wind initial velocity is V_sp[0] = V_se[0] = 10; the ratio of the temperatures is σ_sp = σ_se = 1; and for the initial solar wind number density we took the ratio γ = 0.5. The black-dashed lines in (a) to (d) refer to the result at t = 1 for a solar wind initial velocity of V_sp[0] = V_se[0] = 30.