Betelgeuse, one of the brightest stars in the night sky, has a long-suspected companion star that has now been confirmed for the first time. The discovery was made by a team of astrophysicists using the Gemini North telescope’s ‘Alopeke speckle imager.
Located about four times the distance between Earth and the sun from Betelgeuse, the companion star is six magnitudes fainter in the optical wavelength range and has an estimated mass of around 1.5 times that of the sun. It appears to be a hot, young, blue-white star that has not yet initiated hydrogen burning in its core.
The discovery provides new insights into Betelgeuse’s life and future death. The companion star is likely to have a shortened lifespan due to strong tidal forces, which will cause it to spiral into Betelgeuse within the next 10,000 years.
This finding explains why similar red supergiant stars undergo periodic changes in brightness on a scale of many years. The Gemini North telescope’s high angular resolution and sharp contrasts enabled the detection of the companion star, opening up new opportunities for studying this phenomenon.
The discovery also highlights the capabilities of the International Gemini Observatory, which provided the speckle imaging technique used to detect the companion star. Further studies are planned, including observations in 2027 when the companion returns to its furthest separation from Betelgeuse.
Source: https://phys.org/news/2025-07-hidden-neighbor-astronomers-companion-star.html