Massive stars are among the most important cosmic engines: they trigger or inhibit star formation in stellar nurseries and enrich the interstellar medium with heavy elements, ultimately leading to the formation of Earth-like planets and the development of life. With velocities reaching 3000 km/s and mass loss rates reaching 10-4 solar masses per year, massive star winds play a key role in both the interaction of the massive star with its environment and its very evolution.
In high mass X-ray binaries (HMXBs), the black hole or neutron star accretes matter from the wind of a massive supergiant companion: the stellar wind drives changes in the accretion and thus the system’s X-ray emission. But the interaction of this emission with the wind material can also be used to study the wind itself, in particular its geometry, clumpiness, mass-loss rate and interaction with the compact object. HMXBs are our unique chance to probe individual clumps as opposed to the wind as a whole and offer an independent test of predictions for the properties of massive star winds.
Our aim is to bring together experts in HMXBs and in wind from massive stars in order to bridge the gap betwen X-ray observational studies and wind theory. Our work enables new discoveries with current telescopes, such as ESA's XMM-Newton and NASA's Chandra and NuSTAR, and with future missions such as XRISM and NewAthena.