Utilizing the speckle imager Alopeke from the Gemini North Telescope, part of the NSF’s International Gemini Observatory, astronomers captured direct images of Betelgeuse.
Betelgeuse (right) and its remarkable companions (left). Image credits: International Gemini Observatory/Noirlab/NSF/Aura/M. Zamani, Noirlab of NSF.
Betelgeuse is an 8-million-year-old red supergiant located about 724 light years away on the shoulder of the Orion constellation.
It ranks among the largest known stars, with a radius approximately 1,400 times greater than that of the Sun.
Also referred to as Alpha Orionis or Alpha Ori, Betelgeuse is one of the brightest stars in the sky, radiating more light than 100,000 suns.
The star is nearing the end of its life cycle, and when it eventually explodes, the event will shine brightly, becoming visible for weeks even during daylight.
Betelgeuse experiences a major variability period of roughly 400 days, accompanied by a longer secondary period of about six years.
In 2019 and 2020, a significant drop in Betelgeuse’s brightness occurred, known as the “big dimming” event.
This led to speculation about an imminent supernova explosion, but astronomers later found that a large cloud of dust ejected during the dimming was the true cause.
Although the “big dim” mystery has been resolved, it rekindled interest in studying the red supergiant, prompting new analyses of existing archival data.
One analysis suggested that the presence of companion stars might be responsible for Betelgeuse’s six-year brightness fluctuations.
However, searches conducted by the NASA/ESA Hubble Space Telescope and the NASA Chandra X-ray Observatory did not detect these companions.
Dr. Steve Howell and his colleagues at NASA’s Ames Research Center investigated potential companions of Betelgeuse, referred to as Alpha Ori B or The Betelbuddy, using the Speckle Imager ‘Alopeke at the Gemini North Telescope.
“Speckle Imaging is an astronomical technique that employs very short exposure times to mitigate image distortion caused by Earth’s atmosphere,” they explained.
“This method allows for high resolution, and when combined with the light-gathering power of Gemini North’s 8.1m mirror, it enables the direct detection of faint companions of Betelgeuse.”
Analyzing the light from the companion stars allowed astronomers to identify their characteristics.
The companions appear to be A or B-type main-sequence stars, approximately six magnitudes fainter than Betelgeuse, with an estimated mass of around 1.5 solar masses.
The companion is situated relatively close to Betelgeuse, at about four times the distance between the Earth and the Sun.
This discovery marks the first detection of a close stellar companion orbiting a supergiant star.
Even more remarkably, the companions are within the extensive outer atmosphere of Betelgeuse, demonstrating the exceptional resolution capabilities of “Alopeke.”
“The speckle capabilities provided by the International Gemini Observatory prove to be a vital tool for astronomers across a wide range of applications,” stated Dr. Martin, NSF Program Director at the International Gemini Observatory.
“Providing solutions to the Betelgeuse mystery, which has persisted for centuries, is an exciting achievement.”
Survey results will appear today in the Astrophysical Journal Letters.
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Steve Howell et al. 2025. Possibility of direct imaging discovery of the stellar companion to Betelgeuse. apjl in press; doi: 10.3847/2041-8213/adeaaf
Source: www.sci.news
