In February, NASA’s Imaging X-ray Polarimetry Explorer (IXPE) observed its first accreting neutron star: Hercules X-1, more than 21,000 light-years from Earth. Now a new study based on those observations has upended traditional assumptions about neutron stars and the interior processes that drive these ultra-powerful objects. Hercules X-1 isn’t alone in space. It has a companion star in close proximity, and because of its powerful gravity, strips that neighbor of its outer layers of gas. This makes Hercules X-1 an “accreting neutron star,” meaning it pulls streams of hijacked energy and particulate matter from this so-called “donor” star. The material is dragged along the neutron star’s own intense magnetic field lines, and forms an accretion disk around Hercules X-1. Scientists know a lot about the strength of a neutron star’s magnetic field, Ehlert noted, but have yet to fully grasp the physical structure of that field, how and why it fluctuates over time, and the relationship between accreting neutron star and its donor star. This image is an illustration of an accreting pulsar, or a type of powerful, rotating neutron star actively feeding off a companion star. Image credit: NASA #NASAMarshall #NASA #IXPE #HubbleSpaceTelescope #IXPE #neutronstar