7360 20250117160419.0 10.25518/0037-9565.12337 DOI SCART-2025-0037 Rauw, G. X-raying the wind-wind collisions in HD 168112 and HD 167971 2024 The O-type long-period binary HD 168112 and triple HD 167971 star systems have been known for several decades for their non-thermal synchrotron radio emission. This emission arises from relativistic electrons accelerated in the hydrodynamic shocks of the wind collisions in these systems. Such wind collisions are expected to produce a strong X-ray emission that varies as a function of orbital phase. In wide eccentric binaries, such as our targets, the X-ray emission arises from an adiabatic plasma and its intensity should scale as the inverse of the orbital separation. We present a set of XMM-Newton observations of these systems which help us gain insight into the properties of their wind interactions. NO stars: early-type stars: individual (HD 168112; HD 167971) binaries: close X-rays: stars Blomme, R. Nazé, Y. Volpi, D. Bulletin de la Société Royale des Sciences de Liège 93 2024 3 256-261 ronny.blomme@ksb-orb.be https://popups.uliege.be/0037-9565/index.php?id=12337 https://arxiv.org/abs/2410.14458 published in REFERD