Stellar Winds and Mass Loss in Massive Stars

Massive stars, those exceeding approximately eight solar masses, lose a substantial fraction of their material through stellar winds driven by the transfer of momentum from intense radiation to metal ions in their outer layers. These outflows shape stellar evolution by peeling away the envelope, altering surface composition and angular momentum, and governing the transition to evolved stages such as the Wolf–Rayet phase. Mass loss influences the star’s lifespan, ultimate fate as a supernova or black hole, and the chemical enrichment and mechanical feedback of the surrounding interstellar medium. Key factors regulating wind strength include luminosity, surface temperature, metallicity and proximity to the Eddington limit, where radiative pressure nearly balances gravity. Observations reveal both steady, line-driven winds in O and B stars and episodic or eruptive mass loss in the most luminous objects. Recent advances in multiwavelength diagnostics, hydrodynamic modelling and spatially resolved imaging have refined our understanding of wind clumping, the bi-stability phenomenon and the role of rotation in producing anisotropic outflows. Together, these developments underscore the global significance of stellar winds in cosmic star formation, feedback processes and the progenitors of core-collapse transients.

Research from Nature Portfolio

High-resolution infrared imaging of the archetypal colliding-wind binary WR 140 has provided direct kinematic evidence for dust acceleration under radiation pressure. Multiepoch observations trace the evolution of the dust plume geometry as the WR and O star winds collide and modulate around periastron, revealing a confined ‘Goldilocks zone’ in which dust production and acceleration occur. Geometric modelling demonstrates that the expanding dust shell cannot be described by a constant-speed outflow, but rather undergoes sustained acceleration consistent with line-driven forces acting on newly formed grains. This work offers the first direct record of dust motion under radiative acceleration in a massive-star environment and highlights the complex interplay of orbital dynamics, wind collision physics and radiation pressure in episodic mass loss.

Stellar Winds and Mass Loss in Massive Stars publication trend

The graph below shows the total number of articles in stellar winds and mass loss in massive stars across all publications each year (not limited to Nature Index journals).

Technical terms

Radiatively driven wind: flow of stellar material accelerated by momentum transfer from the star’s radiation field to ions in the atmosphere.

Mass-loss rate: rate at which a star expels mass, typically expressed in solar masses per year.

Eddington limit: luminosity threshold at which outward radiation pressure balances inward gravitational attraction.

Wolf–Rayet star: evolved massive star with dense, high-velocity winds revealed by broad emission lines in its spectrum.

Bi-stability jump: sudden change in wind properties at a critical effective temperature, driven by shifts in iron ionisation.

Metallicity: proportion of elements heavier than helium, which determines the opacity and efficiency of line-driven winds.

References

1. On the Maximum Black Hole Mass at Solar Metallicity. The Astrophysical Journal Letters (2024).
2. New predictions for radiation-driven, steady-state mass-loss and wind-momentum from hot, massive stars. Astronomy & Astrophysics (2023).
3. Radiation-driven acceleration in the expanding WR140 dust shell. Nature (2022).