Orbital modulations of the cavity size along the LOS, l_s, obs, for LS 5039 with different orbital inclination angles. The adopted pulsar spin-down luminosity and the stellar wind velocity are L_sd = 6 × 10³⁶ erg s⁻¹ and v_w = 3 × 10⁸ cm s⁻¹. Solid lines represent the cases with Ṁ = 1 × 10⁻⁷ M_⊙ yr⁻¹ (i.e. the corresponding momentum rate ratio is η ≃ 0.1), while dashed lines are for Ṁ = 1 × 10⁻⁶ M_⊙ yr⁻¹ (i.e. η ≃ 0.01). The black solid line shows binary separation for comparison.