VLA-ALMA Data Confirm Siwarha Companion Traversing Betelgeuse at 2.7 Radii

VLA and ALMA observations at seven frequencies from 22 to 485 GHz resolved Betelgeuse's atmosphere from just above the photosphere outward. The data reveal a localized disturbance consistent with Siwarha's orbital path through the extended envelope, producing density and temperature perturbations that match hydrodynamic models of a low-mass companion embedded in supergiant wind. Post-dimming recovery shows the 2200 K MOLsphere layer persisting while the outer gas has warmed, indicating the 2019-2020 ejection was a transient convective event rather than a permanent structural change.

Earlier single-dish and optical studies attributed the Great Dimming solely to dust formation without resolving companion-induced shocks. The new spatially resolved radio temperatures demonstrate that Siwarha's passage can drive the observed surface asymmetries and may modulate mass-loss rates by factors of two on orbital timescales, a mechanism previously underweighted in red-supergiant evolution tracks.

Future high-resolution imaging and radial-velocity monitoring can test whether Siwarha's orbit is stable or will lead to merger within 10^4 years, directly constraining binary channels for Type II supernova progenitors. Coordinated ALMA-VLA campaigns at higher frequencies would map the inner shock front and quantify momentum transfer into the wind.