High-mass X-ray binaries

This is an artist's impression of Integral’s investigation of high-mass X-ray binaries. Integral has revealed two different types of stars. In the first example (top panel), the neutron star companion is buried deeply in the extended outer envelope of the star. This results in persistent X-ray emission. In the second example (bottom panel), the neutron star only occasionally swallows material from the envelope, causing a sudden brightening of its gamma rays.