Astronomers finally figured out why this one super bright star you can see with your naked eye is blasting out high-energy X-rays.
March 25, 2026
Original Paper
Orbital motion detected in gamma Cas Fe K emission lines
arXiv · 2603.22938
The Takeaway
The star Gamma Cassiopeiae has baffled scientists for decades with its intense radiation; new data proves it has a hidden, 'dead' white dwarf companion that is acting like a vacuum, sucking up gas and heating it to millions of degrees.
From the abstract
A subset of Be stars, typified by the naked-eye star gamma Cas, exhibits unusually bright and hard X-ray emission, the origin of which has remained debated for five decades. We performed high-resolution X-ray spectroscopic monitoring of gamma Cas with the Resolve instrument aboard the X-Ray Imaging and Spectroscopy Mission (XRISM). X-ray lines from the ultra-hot plasma and fluorescence from cooler material exhibit Doppler shifts consistent with orbital motion, not of the Be star itself, but of i