Restrictions for the position of NGC 5907 X-1 in the ṁ₀ − μ plane. The red horizontal line corresponds to the mass accretion rate of ṁ₀ = 6500 (accretion efficiency η ≃ 0.15). The black solid line corresponds to p_eq = p = 1.137 s. The dotted spin-up line shows the lower limit for ṁ_in set by inequality (32) using period derivation |ṗ| = 5 × 10⁻⁹ s s⁻¹. We use here M = 1.4 M_⊙, R = 10 km, I = 1.5 × 10⁴⁵ g cm², and p = 1.137 s.