The Transport of Angular Momentum for Massive Stars. I. Formation of Slowly Rotating Early-type Nitrogen-sequence Wolf–Rayet Stars

Abstract The evolutionary scenario of early-type nitrogen-sequence Wolf–Rayet (WNE) stars predicts a slowly rotating subclass that typically forms after the red supergiant phase. Their slow rotation rates are attributed to stellar winds that remove angular momentum transferred outward during core contraction. We incorporate improved prescriptions for internal gravity waves and the magnetic Tayler instability into single massive star evolution models. Our simulations successfully produce slowly rotating WNE stars and determine optimal parameters for both mechanisms ( A ≥ 10 for internal gravity waves, α = 0.01 for the revised Tayler instability). The results demonstrate that the efficiency of angular momentum transfer in massive stars is significantly enhanced compared to low-mass stars; both processes can self-consistently explain the slow rotation of WNE stars, confirming their efficiency in angular momentum redistribution and providing crucial theoretical support for the existence of this predicted stellar population.