Researchers Confirm Betelgeuse's 2,100-Day Dimming Cycle With 6-Year Companion Orbit
Updated
Updated · Space.com · Nov 3
Researchers Confirm Betelgeuse's 2,100-Day Dimming Cycle With 6-Year Companion Orbit
3 articles · Updated · Space.com · Nov 3
Summary
January 2026 observations from ESO's Very Large Telescope and NASA's Hubble delivered the clearest images yet of a faint companion orbiting Betelgeuse, tying the red supergiant's long-mysterious 2,100-day fading cycle to that star.
The companion, dubbed Siwarha, appears to circle Betelgeuse about every six years inside its outer chromosphere, where its gravity stirs gas and dust into a dense wake that can cross Earth's line of sight and dim the star.
Betelgeuse has also faded again since August, slipping from magnitude +0.5 to +0.95 and now appearing slightly dimmer than Aldebaran, though the new drop alone does not prove the companion caused it.
That longer cycle is separate from Betelgeuse's roughly 430-day pulsation, while the far more severe 2019-2020 Great Dimming was traced to a giant plasma ejection that formed a dust cloud and likely coincided with both the pulsation minimum and orbital interference.