An invisible companion consuming material from the naked-eye star gamma-Cas has been revealed as the culprit for curious X-rays coming from the stellar system, closing the case on a mystery that has puzzled astronomers for more than fifty years. Unique high-resolution observations made by the X-Ray Imaging and Spectroscopy Mission (XRISM) revealed that the X-rays are linked to the orbital motion of a companion white dwarf star, enabling astronomers to finally solve the mystery.

A team of astronomers led by the Center for Astrophysics | Harvard and Smithsonian have for the first time used galactic archaeology, the study of detailed chemical fingerprints in deep space, to trace the history of a galaxy outside the Milky Way. The study, published today in the journal Nature Astronomy, demonstrates a new way to reconstruct the evolution of distant galaxies, and opens up a new field of astronomy, called “extragalactic archaeology.”