Researchers at Louisiana State University offer a fresh view on Betelgeuse, the famous red supergiant, explaining unusual fluctuations in its light by proposing a past stellar merger. The new work, shared on the arXiv preprint server, outlines findings from a set of computer simulations that model Betelgeuse as a merger product and explore how such an event could alter its brightness and behavior.
The simulations place a large star of about 16 solar masses beside a smaller companion of roughly four solar masses. When the two approach and then separate within a common envelope, the smaller star engages with the helium core of the bigger partner. This interaction transfers both orbital and thermal energy, creating a pulse that travels from the core outward to Betelgeuse’s surface, potentially triggering the observable brightening and dimming patterns.
In certain scenarios, the merger also drives material loss. The gravitational energy released during the coalescence converts into kinetic energy, ejecting matter into space. The model estimates mass loss could reach as much as 0.6 Earth masses, with gas moving at speeds in the 200 to 300 kilometer per second range.
One measurable hint supporting a merger history is Betelgeuse’s rapid rotation, currently around 5.5 kilometers per second, nearly triple the Sun’s rotation rate of about 2 km/s. This rotation implies a merged system consisting of a relatively massive main-sequence star, about 15–17 million Earth masses, and a smaller companion of roughly 1–4 million Earth masses, in line with the scale expected for a binary merger in a massive star’s life.
Direct observations by the Hubble Space Telescope captured highly energized material moving through Betelgeuse’s outer atmosphere at speeds around 322 thousand kilometers per hour between late 2019, and the changes persisted into 2020. By February 2020, Betelgeuse had faded to well below its previous brightness, stirring widespread curiosity that the star might be headed for a supernova in the near future.
The study also notes that artificial intelligence has played a role in past efforts to model and classify supernova events, demonstrating how machine-driven analysis can complement traditional astrophysical methods. This approach helps researchers test different merger scenarios and compare them with observed variability, strengthening the case for a merger-driven explanation of Betelgeuse’s dramatic behavior.