Radio images suggest a link between Betelgeuse’s changing outline and its companion’s expected orbit, offering clues to how a smaller star may influence a giant’s later life.

Betelgeuse, the bright red supergiant marking Orion’s shoulder, may have another star stirring its atmosphere from within. Its recently identified companion, Siwarha, is thought to orbit at a distance of only about twice the giant’s radius. New radio observations suggest that this close neighbor is leaving a visible mark on the shape of Betelgeuse’s outer gas, even though the companion itself is too faint to appear in those observations.

Researchers proposed Siwarha’s existence in 2024 to explain Betelgeuse’s mysterious 2,100-day brightness cycle. Direct imaging and spectroscopic studies of the star’s light have since supported its existence. The companion’s name means “her bracelet,” a reference to Betelgeuse’s Arabic meaning, “the hand of al-Jawza.”