Overview
- A multi-observatory study published this week combines VLA and ALMA data to show Betelgeuse's outer atmosphere has largely warmed back to typical brightness temperatures, with a peak near 3,500 K at about 2.7 stellar radii.
- The same radio work confirms a cooler molecular layer, the MOLsphere, where temperatures fall to roughly 2,200 K between the visible surface and the hotter chromosphere.
- Astronomers now treat Siwarha as a probable close companion first imaged in early 2026 that orbits so close it moves through Betelgeuse's extended atmosphere and is detected mainly by its dynamical effects rather than direct radio emission.
- High-resolution radio maps show modest, time-correlated elongation of Betelgeuse's radio disk that matches Siwarha's predicted orbital positions and is interpreted as a wake or perturbation of the giant star's outer gas.
- Researchers say more phase-resolved monitoring and next-generation instruments are needed to fix Siwarha's orbit and measure how strongly the companion drives mass loss or dust formation, a key factor for models of late-stage massive-star evolution.