An international team of astronomers led by Dr. Lynn Matthews of MIT's Haystack Observatory has found evidence that a hidden companion star is deforming the atmosphere of the red supergiant Betelgeuse, infohub.kz reports.
Radio observations show that the close companion, Siwarha, is moving through the red supergiant's outer layers, churning up gas and stretching its atmosphere into an oval shape. The study, carried out with specialists from the Harvard-Smithsonian Center for Astrophysics, the University of Manchester and the European Southern Observatory, has been published in the scientific journal "The Astronomical Journal."
The scientists combined radio data from the Karl G. Jansky Very Large Array (VLA) and Chile's ALMA observatory covering the period from 2021 to 2026 at seven frequencies ranging from 22 to 485 gigahertz.
The researchers attribute the disturbances to the small star Siwarha, whose existence was first predicted in 2024 to explain the giant's 2,100-day brightness cycle. In Arabic, the companion's name means "bracelet," complementing the name of Betelgeuse itself ("the hand of the twin"). The companion lies just about two radii of the supergiant from its center and orbits directly inside its extended gas envelope, raising a hydrodynamic wave much like a fast boat on water.
Siwarha itself is too faint to be detected directly in radio waves, but its presence was revealed by the behavior of the surrounding environment. Betelgeuse's atmosphere regularly stretches into an oval at radio wavelengths, with the greatest elongation coinciding with the points at which the companion is farthest from the star's center.
The astronomers also confirmed the presence of a cold molecular gas layer (the "MOLsphere") with a temperature of 2,200 kelvins, 1,000 degrees cooler than the photosphere, and recorded heating of the atmosphere following the major dimming event of 2019-2020.