Astronomers have discovered a celestial phenomenon that could change our understanding of massive star evolution. Using advanced telescopes, they've observed a faint companion star, Siwarha, carving a trail through the atmosphere of Betelgeuse, a red supergiant star. This discovery sheds light on decades-old stellar puzzles and offers new insights into the behavior of massive stars.
Betelgeuse, located in the constellation Orion, is an 8-million-year-old star that's one of the most luminous and largest known. It's nearing the end of its life span and will soon explode, an event that will be visible during the day for weeks. Astronomers have been studying Betelgeuse's behavior for decades, with increased curiosity after it appeared to 'sneeze' and dim unexpectedly in 2020.
Two distinct periods of variation in Betelgeuse's behavior have been particularly puzzling: a short 400-day cycle attributed to pulsations within the star, and a longer 2,100-day secondary period. Scientists have considered various explanations, including large convection cells, dust clouds, magnetic activity, and the presence of a hidden companion star.
Recent studies concluded that the long secondary period was best explained by a low-mass companion orbiting deep within Betelgeuse's atmosphere. A team of scientists reported a possible detection, but evidence was lacking until now. Astronomers have now found firm evidence that a companion star is disrupting Betelgeuse's atmosphere, including changes in the star's spectrum and the speed and direction of gases in the outer atmosphere due to a trail of denser material, or 'wake'.
This trail appears just after the companion star crosses in front of Betelgeuse every six years, confirming theoretical models. Dr. Andrea Dupree, an astronomer at the Harvard & Smithsonian's Center for Astrophysics, explains it as a ripple effect in Betelgeuse's atmosphere, similar to a boat moving through water. This discovery provides direct signs of the wake or trail of gas, confirming that Betelgeuse has a hidden companion shaping its appearance and behavior.
The team's findings will be published in the Astrophysical Journal, offering a significant advancement in our understanding of massive star evolution.
