06/15/2026
James Webb has mapped convection patterns on the surface of a nearby red giant star for the very first time.
Webb's NIRISS aperture masking interferometry mode achieved 9 milliarcsecond angular resolution observing Betelgeuse β the red supergiant in Orion 700 light years from Earth β resolving the star's surface into a detailed map of brightness and temperature variations. Bright granular structures 200 to 400 solar diameters across rise and fall with a 400-day convective.
The Betelgeuse convection map reveals the entire stellar surface is dominated by just 2 to 3 massive convection cells at any time β unlike the millions of small granulation cells on the Sun β explaining the dramatic irregular brightness variations Betelgeuse displays. The Great Dimming event of 2019 and 2020 that caused speculation about an imminent supernova.
The Webb convection maps provide observational constraints for stellar interior models, directly testing predictions of convective mixing length theory that underpins all stellar evolution calculations in astrophysics. Understanding Betelgeuse's convective structure also refines the predicted timing of its eventual supernova, which will be visible in daylight from Earth when it finally occurs sometime in the next 100,000 years.
Source: NASA James Webb Space Telescope Science Institute, Royal Astronomical Society, Astrophysical Journal Letters, 2025