ALMA Reveals Long-Lived Hotspots on the Surface of Betelgeuse
ALMA Reveals Long-Lived Hotspots on Betelgeuse’s Bubbling Surface
Observations obtained in 2023 with the Atacama Large Millimeter/submillimeter Array (ALMA) reveal the uneven surface of Betelgeuse, showing bright hotspots and an irregular, corrugated outline shaped by enormous convective motions. Located approximately 600 light-years from Earth in the constellation Orion, the red supergiant possesses a radius about 800 times that of the Sun. This immense physical scale allows ALMA’s longest-baseline configuration to resolve atmospheric structures down to a resolution of roughly seven milliarcseconds, according to data published by the European Southern Observatory and reported by Sci.News and Tech Times.
The Tech TL;DR:
- Target Entity: Betelgeuse, a red supergiant star situated roughly 600 light-years away.
- Key Instrumentation: ALMA in its longest-baseline configuration, achieving a seven-milliarcsecond resolution.
- Core Finding: Detection of persistent hotspots surviving for at least seven years, driven by deep stellar convection.
Atmospheric Benchmarks and Submillimeter Resolution Metrics
The 2023 ALMA campaign mapped an average atmospheric temperature of approximately 2300 K across the stellar disk. Two primary hotter regions were identified positioned to the northeast and southwest. Data processing indicates that the brightest hotspot reaches temperatures up to 800 K higher than the surrounding gas. These thermal anomalies correlate directly with massive convective currents originating from deep layers within the stellar interior, where rising hot gas generates significant shocks upon reaching the outer atmosphere.
Surface geometry measurements further demonstrate that Betelgeuse deviates severely from a spheroidal shape. ALMA recorded apparent radius variations of up to six percent, while fainter emission structures extend several stellar radii outward. Molecular tracing of silicon monoxide (SiO) and carbon monoxide (CO) highlights an intensely clumpy, disrupted circum-stellar environment.
Long-Term Persistence Versus Current Stellar Models
A comparative analysis between the 2023 ALMA dataset and archival 2015 observations yielded unexpected results. Lead author Bill Dent, an astronomer at ESO, noted that the prominent northeastern hotspot persisted in nearly the exact spatial location with comparable intensity over the seven-year span. Standard theoretical convection models predict lifetimes for large-scale convective cells that are significantly shorter than this observed duration. This temporal stability challenges current assumptions regarding atmospheric circulation in dying massive stars.
Recent investigations also point toward the presence of a close companion star capable of deforming the chromospheric envelope, although direct causal links to the stable hotspots require continued interferometric monitoring.
Stellar Evolution and Future Supernova Projections
As Betelgeuse advances through the final phases of its stellar evolution, high-resolution submillimeter imaging provides a baseline for tracking mass loss and atmospheric dynamics prior to its eventual collapse into a supernova. Continued integration of interferometric data will clarify whether these persistent thermal features remain magnetically or convectively anchored.
