Hidden Companion Star Siwarha Unveiled Inside Betelgeuse's Turbulent Atmosphere

A hidden companion star, named Siwarha, has been discovered orbiting within the atmosphere of Betelgeuse, the famous red supergiant. First detected indirectly in 2023, its presence explains the star's unusual brightness fluctuations and rapid rotation. Researchers now believe Siwarha's movements create dramatic ripples, much like a speedboat cutting through water.

The discovery was made using NASA's Hubble Space Telescope, alongside the CHARA Array. A team led by Andrea Dupree used high-resolution spectroscopy to study Betelgeuse's chromosphere and stellar winds. These observations revealed variations pointing to a nearby companion—Siwarha.

Siwarha, a low-mass star between half and 1.5 times the sun's mass, completes an orbit every six years. As it moves through Betelgeuse's outer layers, it leaves a turbulent wake. This disturbance causes the supergiant to dim and brighten in a repeating cycle.

The entire star—its surface, atmosphere, and surrounding gas—reacts to Siwarha's gravitational pull. Scientists suggest this interaction may be one of the clearest cases of a star spiralling into its companion. Currently hidden behind Betelgeuse, Siwarha is expected to re-emerge in 2027.

The findings are set to be published in The Astrophysical Journal.

Siwarha's discovery sheds light on Betelgeuse's mysterious behaviour, including its erratic brightness and fast spin. If confirmed, this system could provide a rare, detailed look at how companion stars influence red supergiants. The next opportunity to observe Siwarha directly will come when it reappears from behind Betelgeuse in 2027.