Strange star mystery solved after 50 years

Artist’s concept of the strange star Gamma Cassiopeiae (aka gamma-Cas) and its small-but-dense white dwarf companion. New data from X-ray space telescope XRISM shows a white dwarf consuming the disk of ejected material from gamma-Cas. This generates the highly variable X-ray emission coming from the system. Image via ESA/ Y. Nazé (CC BY-SA 3.0 IGO).

• The strange star Gamma Cassiopeiae has intense X-rays associated with it. For more than 50 years, astronomers have wondered why.
• A...