The XRISM mission, an X-ray imaging and spectroscopy observatory led by Japan with participation from the NASA, has for the first time observed a pulsar capturing the stellar wind from its companion star, according to an official statement released on September 18, 2026.
This system, named BP Crucis, is a high-mass X-ray binary located about 13,000 light-years away in the constellation of the Southern Cross. The primary star, Wray 977, is a blue hypergiant approximately 40 times more massive than the Sun, emitting a stellar wind composed of a continuous flow of ionized gas.
The companion to this star is a pulsar, a very compact neutron star called GX 301-2, which rotates every 11 minutes and emits a beam of X-rays sweeping across Earth. During its 41.5-day orbit, the pulsar crosses twice through a dense plasma stream originating from the stellar wind, causing intense X-ray bursts.
Observations show that the pulsar captures this stellar wind, initially forming a turbulent accretion disk around itself. Then, when the disk can no longer be sustained, the plasma falls directly onto the pulsar, fueling its X-ray bursts. Later, a new disk reforms, rotating in the opposite direction to the first due to the wind’s flow.
Roi Rahin, a researcher at the University of Maryland and NASA’s Goddard Space Flight Center, emphasizes that this direct observation of stellar wind plasma falling onto a compact object allows precise testing of astrophysical models of these extreme phenomena.
These results are published in the journal Science Advances.
