massivestars

Massive stars are stars with initial masses significantly greater than the Sun’s, usually defined as M ≳ 8 solar masses. They are hot and luminous, with short lifetimes of only a few million years. In young stellar populations they dominate the light output and are commonly found in OB associations and star-forming regions. Their spectra show strong features of ionized elements, and they often exhibit powerful stellar winds.

On the main sequence, massive stars fuse hydrogen predominantly via the CNO cycle. Their high luminosities drive strong radiation pressure and substantial mass loss through winds, which can shape their later evolution. Their evolution proceeds rapidly through successive fusion stages, expanding to blue or red supergiant phases and building toward an iron core.

After exhausting their nuclear fuel, massive stars undergo core collapse, producing core-collapse supernovae (Type II) and leaving behind compact remnants such as neutron stars or black holes. In the most massive cases, pair-instability processes can completely disrupt the star, leaving no remnant. The exact outcomes depend on the initial mass, composition (metallicity), rotation, and binarity.

Massive stars are key drivers of galactic evolution. They synthesize and disperse heavy elements into the interstellar medium via winds and supernova explosions, and their intense ultraviolet radiation ionizes surrounding gas. This feedback regulates star formation in galaxies. Binary interactions can alter their evolution, producing stripped stars, X-ray binaries, and, in some environments, gamma-ray bursts.