New Images Confirm Betelgeuse's 6-Year Companion Siwarha, Ending 100-Year Search

Q: Could Betelgeuse's newly discovered hidden companion trigger its highly anticipated supernova much sooner than scientists originally predicted?

Possibly, but scientists do not know whether it would make Betelgeuse explode anytime soon. The newly imaged companion, likely a 2.6-to-3.1-solar-mass star orbiting Betelgeuse about every six years, could gravitationally disturb the red supergiant’s outer layers, wind and mass loss. That matters because mass loss is one of the biggest uncertainties in predicting how massive stars evolve and when they finally collapse as supernovae. Researchers say the companion could therefore alter the timing or even some details of Betelgeuse’s eventual explosion. But there is no evidence that this means a supernova is imminent on human timescales. Betelgeuse is still generally thought to be a star expected to explode sometime within roughly 10,000 to 100,000 years, not in the next few years because of this discovery. The companion may shift that timetable, but astronomers cannot yet say by how much, or in which direction. Miguel Montargès, a co-author of the new study, has said the interaction could either accelerate or delay the supernova. There is another reason for caution: the companion detection, while described as the strongest evidence yet, is still awaiting a critical follow-up observation in 2027, when the object should appear on the opposite side of Betelgeuse if it is truly bound. So the hidden companion may reshape predictions for Betelgeuse’s death, but it does not currently support claims that the star is about to explode much sooner than expected.

Q: Is the elusive Betelbuddy truly a hidden star, or just a cosmic illusion created by the supergiant's chaotic outbursts?

Betelbuddy is most likely a real companion star, not just a trick of Betelgeuse’s unruly atmosphere — but astronomers are still treating it as provisional until they see it again in the expected place. The new evidence is stronger than past hints because it is a direct high-contrast image taken with the European Southern Observatory’s Very Large Telescope and SPHERE instrument, which was designed to block a bright star’s glare and reveal faint nearby objects. The object appeared in December 2024 exactly when orbital models predicted a companion should be farthest from Betelgeuse and easiest to detect. Its inferred mass, about 2.6 to 3.1 times the Sun’s, also fits a plausible stellar companion rather than a random clump of gas or dust. That said, caution remains warranted because Betelgeuse is notoriously messy. Its surface pulsates, it sheds dust, and radio and optical observations show an irregular, changing atmosphere and surrounding envelope. Those outbursts helped produce false alarms and uncertainty in earlier searches, including after the 2019 “great dimming,” which was ultimately tied to dust and atmospheric activity rather than an imminent explosion. So the balance of evidence now favors a hidden star, likely a young B-type companion orbiting every six years. But astronomers still want a decisive follow-up in 2027, when the object should appear on the opposite side of Betelgeuse. If it does, the case for Betelbuddy as a bona fide star will be close to settled.

3 articles · Updated · Smithsonian Magazine · Aug 3

December 2024 images from Chile’s Very Large Telescope gave astronomers their clearest evidence yet that Betelgeuse is orbited by the faint companion Siwarha, in findings published July 28.
The detection came when the companion was at its widest apparent separation from Betelgeuse, and researchers used a planet-hunting instrument that blocks the host star’s glare to reveal it.
Analyses suggest Siwarha is 2.6 to 3.1 times the sun’s mass and circles Betelgeuse about every six years, heavier than earlier expectations but consistent with recent models.
A 2027 observation on the far side of Betelgeuse is still needed for full confirmation, though the team says there is now little room for doubt after a century of speculation.
The result could reshape forecasts for Betelgeuse’s end, because interaction with a companion may alter when the red supergiant—about 550 light-years away—eventually goes supernova.