The star γ Cas, visible to the naked eye in the constellation Cassiopeia, has confused astronomers for decades. It produces X-rays far more intense and hotter than what scientists expect from a typical massive star. New observations using the Resolve instrument aboard Japan's XRISM space telescope now link these emissions to a white dwarf orbiting the star. This discovery also confirms a long-predicted type of binary system that had never been clearly identified. The findings, led by researchers at the University of Liège, were published in Astronomy & Astrophysics .

What Makes Gamma Cassiopeiae So Unusual

γ Cassiopeiae was the first star classified as a Be-type star, identified in 1866 by Italian astronomer Angelo Secchi. These massive stars spin rapidly and regularly eject material into space.…