Betelgeuse Companion Star Seen in First Image

Astronomers have unveiled the first image of a faint companion star orbiting Betelgeuse, offering the strongest evidence yet that one of the night sky's most famous stars is not alone.

The finding was based on observations by the European Southern Observatory's Very Large Telescope in Chile. The observations were taken in December 2024, when the companion star was farthest from Betelgeuse, and the results were published in Astronomy & Astrophysics.

Lead study author Miguel Montarges of the Paris Observatory said the work was "the conclusion of a century-long quest". He said the team had shown that Betelgeuse "is not single" but is accompanied by a faint stellar companion.

Betelgeuse is a red supergiant in the Orion constellation and is about 1,000 times bigger than the Sun. Scientists had long studied regular changes in its brightness. In 2024, astronomers predicted the flickering was caused by a much smaller companion star crossing nearby.

The companion, dubbed Betelgeuse B, had been thought to have only about 1.5 times the Sun's mass. The new observations indicated it is heavier, at two to three times the Sun's mass, which helped astronomers detect it despite Betelgeuse's brightness.

Montarges said more observations are needed to definitively prove the companion's existence, but added that "there is very little space left for doubt".

Betelgeuse also drew attention when it dimmed for five months between 2019 and 2020. Scientists first considered whether it might be nearing a supernova explosion, but later observations showed the dimming was caused by material ejected from the star's surface forming a dust cloud that blocked its light.