Verylowmass

Very-low-mass stars, often abbreviated VLM, are stars with masses roughly 0.075 to 0.50 solar masses. They occupy the lower end of the main sequence on the Hertzsprung–Russell diagram and are typically of spectral types late M and cooler. Like other hydrogen-burning stars, they fuse hydrogen in their cores, but their small masses lead to cooler interiors, low luminosities, and cooler surface temperatures. The boundary with brown dwarfs lies near the hydrogen-burning minimum mass, commonly around 0.072–0.08 solar masses, depending on metallicity and age.

Below about 0.35 solar masses, VLM interiors are fully convective. This structural difference has implications for magnetic activity and chemical mixing. Their effective temperatures generally range from about 2400 to 3800 kelvin, and their luminosities are a tiny fraction of the Sun’s. VLM stars have very long lifetimes, evolving slowly and remaining on or near the main sequence for trillions of years in theory.

VLM stars are among the most common stellar objects in the Milky Way, contributing significantly to the local stellar population and the overall stellar census. They are central to studies of the initial mass function and star formation, and their small radii and low luminosities make them attractive targets for exoplanet searches, including systems with small, potentially habitable-zone planets. The term is sometimes distinguished from substellar brown dwarfs, which cannot sustain stable hydrogen fusion.