ALMA Reveals Long-Lived Hotspots on Betelgeuse's Bubbling Surface

ALMA’s 2023 longest-baseline imaging of Betelgeuse resolved a 7 mas-scale atmosphere averaging 2300 K and identified two hotspots, one up to 800 K hotter, located northeast and southwest of the stellar disk. Comparison with 2015 data shows the northeastern hotspot persisting for at least seven years, far longer than predicted convective lifetimes, while the star’s apparent radius varies by ~6% and molecular emission (SiO, CO) reveals a clumpy, extended envelope.