In the binary system BP Crucis, a giant star loses gas through a stellar wind. Its compact companion, a pulsar, captures some of that material, powering intense X-ray activity.
The Japan-led XRISM observatory has traced that inflow using its Resolve instrument. Iron absorption features in the X-ray spectrum indicate gas moving toward the pulsar at about 540,000 kilometres per hour. Spectroscopy makes it possible to study motion in a system too distant to inspect directly.
The researchers propose that captured gas first forms a turbulent disk, which can break down and feed material more directly onto the compact star. The observations help test how matter behaves under extreme gravity. They also show why changes in X-ray brightness can reveal the otherwise hidden interaction between two stars.
Source: NASA report (2026-09-18).
