NASA Telescopes Capture First-Ever Companion Star Orbiting Massive Red Supergiant Betelgeuse

Astronomers have successfully seen the companion star of a type of supernova and thus proved its approach was responsible for this kind of exigent explosion. The faint companion is seen at its maximum distance from Betelgeuse thanks to NASA's Chandra X-ray Observatory and the Hubble Space Telescope—observations made by a team of researchers from Carnegie Mellon University (CMU). It represents the first confirmed sighting of a companion star orbiting such an enormous and evolved celestial behemoth—one that is more than 700 times as large as our Sun and thousands of times brighter.

Discovery of Betelgeuse's Tiny Companion Challenges Theories of Binary Star Formation

As per a report published in The Astrophysical Journal on October 10, the finding was made after the Gemini North Telescope in Hawaii captured a faint image near Betelgeuse. Researchers had long suspected a companion due to the star's periodic dimming, but it had never been observed directly. Anna O'Grady, a postdoctoral fellow at CMU, stated that this represents the deepest X-ray observation of Betelgeuse to date, as the companion had always remained hidden behind the bright glare of the giant star.

Prior to their observations, it was expected that Betelbuddy could be a white dwarf or a neutron star, but the absence of known accretion signatures eliminated both cases. Now, researchers think the companion could be a nascent sun-like star, a class of “extreme mass ratio binaries”. Moreover, 16-17 times more massive than the Sun, believed to be Betelgeuse. It means that this star couple is highly lopsided.

Researchers discovered binary systems with stars of similar masses, potentially reshaping theories on massive star evolution. Betelgeuse's proximity enabled the discovery, despite rare observational challenges.
The study suggests that future observations with next-generation telescopes could help understand the influence of Betelbuddy on Betelgeuse's evolution and its potential supernova fate.