Astronomers have finally verified the existence of a companion star around the red supergiant Betelgeuse, one of the brightest stars which are visible to the naked eye in the sky. Researchers from Carnegie Mellon University (CMU) used NASA's Chandra X-ray Observatory and the Hubble Space Telescope to image the faint companion at its most distant from the supergiant. This is a historic first exploration, where the discovery of a companion orbiting such a large, evolved star more than 700 times bigger and thousands of times brighter than the Sun.
Discovery confirms long-standing theories
The discovery, which was published in The Astrophysical Journal on October 10 (2025), follows years of speculation. As per the research, the Gemini North Telescope in Hawaii detected a faint glimmer near Betelgeuse, long suspected to be a hidden stellar partner. Periodic dimming in Betelgeuse’s brightness had hinted at a binary system, but no direct evidence existed until now.
‘Betelbuddy’: A star like our sun?
Anna O'Grady, the Lead author and a postdoctoral fellow at CMU stated that this is the deepest X-ray observation of Betelgeuse ever made. The new star, which she dubbed 'Betelbuddy', looks like an immature, Sun-like star and not a white dwarf or neutron star, as thought earlier. Betelgeuse itself is 16 to 17 times bigger than the Sun, so this is an extreme mass ratio binary system, which is a very unusual phenomenon in the universe.
What does this do to star evolution?
This finding upsets the current theories of the formation of binary stars, which generally consist of similar-mass stars. Betelgeuse's proximity to our planet allowed for this unusual sighting in spite of the blinding brightness of the supergiant.
Researchers think that the future-generation telescopes may uncover more about how Betelbuddy affects Betelgeuse's life cycle and its eventual supernova explosion, which will provide greater insight into the development of massive stars in our universe.