Evolutionary path, from ZAMS to the merger, of an NSBH binary from channel Ia. From top to bottom, we show the evolution of the orbital period P_orb, eccentricity e, component masses M_1, 2, star radii R_1, 2, surface angular velocity over the critical value (ω/ω_crit)_1, 2, and the spin of the primary χ₁. The solid blue line represents the star that evolves to form a BH, while the red dashed-dotted line represents the star that becomes an NS. In the panel of stellar mass evolution, we indicate the onset of the stable mass transfer (SMT), the first core collapse (CC1), the common envelope (CE) phase, and the second core collapse (CC2) with the short vertical lines.