Astronomers have directly imaged a previously hypothesized companion star to Betelgeuse, located approximately 4 AU from the red supergiant. Using the Gemini North Telescope’s speckle imager ‘Alopeke, scientists detected an A- or B-type pre-main sequence star with about 1.5 solar masses, significantly fainter than Betelgeuse in visible light.
The discovery offers a potential explanation for Betelgeuse’s six-year variability cycle, suggesting the companion’s influence on dust distribution within the red supergiant’s extended atmosphere. The close binary system’s future involves the eventual consumption of the companion star by Betelgeuse within the next 10,000 years, potentially affecting Betelgeuse’s evolutionary timeline and supernova event.
Betelgeuse is one of the most iconic stars in the night sky, known for its turbulent and unpredictable nature. Located about 650 light-years away, the star is a true giant, spanning nearly 700 times the Sun’s radius. The Great Dimming, which occurred in 2019 and 2020, was initially thought to be caused by a supernova, but astronomers later discovered that it could be attributed to the effects of a smaller companion star.
The newly imaged companion star is estimated to have about 1.5 times the mass of the Sun and shines six magnitudes fainter than Betelgeuse in visible light. Based on its color and brightness, it appears to be an A- or B-type pre-main sequence star – a hot, blue-white object that hasn’t yet begun hydrogen fusion in its core.
The discovery also offers a possible new lens for interpreting variability in red supergiants. The presence of a close-in companion could help explain the long-term brightness changes observed in stars like Betelgeuse. However, their end will not be harmonious, as strong tidal forces will eventually pull the smaller star into the supergiant’s outer layers, dooming it to be consumed within the next 10,000 years.
Astronomers will have their next prime opportunity to study the companion in November 2027, when it reaches greatest elongation – its farthest and most detectable separation from Betelgeuse.
Source: https://www.astronomy.com/science/betelgeuses-long-lost-companion-emerges-from-the-shadows