Astrophysicists have made a surprising discovery regarding the companion star of Betelgeuse, one of the brightest stars visible from Earth. Instead of the expected remnants of a stellar evolution, such as a white dwarf or neutron star, the companion has emerged as a young, Sun-like star, officially designated as α Ori B and nicknamed Siwarha. This finding sheds new light on the complexities of Betelgeuse’s past and its binary system.
Located approximately 548 light-years away in the Orion constellation, Betelgeuse is a red supergiant star nearing the end of its life. With a mass estimated between 16.5 and 19 times that of the Sun and a radius about 764 times larger than our star, it has long puzzled astronomers with its erratic brightness. Researchers observed fluctuations in its luminosity, which indicated the presence of a binary companion potentially on a six-year orbit. This orbit was calculated to bring the companion into an optimal observing position in December 2024.
During this observational campaign, multiple telescopes, including the Chandra X-ray Observatory, captured images that confirmed the existence of Siwarha for the first time. Astrophysicist Anna O’Grady from Carnegie Mellon University explained that if the companion were a white dwarf or neutron star, it should generate X-ray emissions by pulling material from Betelgeuse. However, the Chandra data showed no signs of such emissions, effectively ruling out these possibilities.
Instead, O’Grady and her colleagues propose that Siwarha is a young F-type star, likely still in the process of settling into the main sequence. If this is accurate, both Betelgeuse and Siwarha could have formed together approximately 10 million years ago. The disparity in their development is striking; while Betelgeuse is rapidly approaching its demise, Siwarha is just beginning its stellar life.
The unexpected mass ratio between the two stars poses intriguing questions for researchers. Typically, when stars are born together, their masses are expected to be more closely aligned. O’Grady noted, “This opens up a new regime of extreme mass ratio binaries,” emphasizing that such configurations are rare and challenging to identify. The discovery of Siwarha and its unique relationship with Betelgeuse has the potential to expand our understanding of binary star systems.
The research detailing these findings has been published in The Astrophysical Journal, marking a significant contribution to the field of astrophysics. As astronomers continue to study Betelgeuse and its companion, they hope to unravel more about the mysteries of these celestial bodies and their evolutionary paths.
