Betelgeuse, one of the most famous stars in the night sky, has a close companion, and that may explain why it dimmed dramatically in 2019-20.
About 640 light-years from the solar system, red supergiant star Betelgeuse in the constellation Orion is famous not only for its unmistakable color, but also because it’s one of the closest stars that could soon explode as a supernova.
Betelguese And Its ‘Great Dimming’
Approximately 700 times larger than the sun, Betelgeuse has puzzled astronomers for years because it waxes and wanes in brightness every six years, with its recent “Great Dimming” event ultimately attributed to a dust cloud ejected by the star.
Scientists suspected it may have been caused by a companion star, but failed to detect it using NASA’s Hubble Space Telescope or the Chandra X-ray Observatory. Now it’s been found, after a team of astrophysicists led by Steve Howell, a senior research scientist at NASA Ames Research Center, has pointed the Gemini North Telescope in Hawaii at Betelgeuse. The team’s findings were published today in The Astrophysical Journal Letters.
How ‘Betel-Buddy’ Was Found
Using the telescope’s Alopeke speckle imager — which takes high-resolution short exposures to minimize the blurring effects of Earth’s atmosphere — the companion star was found. Six magnitudes dimmer than Betelgeuse, the young, blue-white star orbits Betelgeuse from just four times the Earth-sun distance. That’s well within the red supergiant star’s outer atmosphere.
The Alopeke imager was decisive. “Gemini North’s ability to obtain high angular resolutions and sharp contrasts allowed the companion of Betelgeuse to be directly detected,” said Howell. “Papers that predicted Betelgeuse’s companion believed that no one would likely ever be able to image it.”
Why Betelgeuse Is Special
Betelgeuse is a special star. It’s the archetype of a red supergiant star near the end of its life cycle, during which its outer atmosphere is expanding. This is the first direct observation of a companion star orbiting within the outer atmosphere of a supergiant. It’s thought that the companion may spiral inward and be consumed by Betelgeuse within the next 10,000 years.
Astronomers are already preparing for November 2027, when the companion will be at its maximum separation from Betelgeuse, offering the best chance yet for further observation and analysis.
Wishing you clear skies and wide eyes.
