X-raying the wind-wind collisions in HD 168112 and HD 167971

TL;DR

This study uses XMM-Newton observations to analyze the wind-wind collision regions in the binary systems HD 168112 and HD 167971, aiming to understand their X-ray emission characteristics and how they relate to orbital dynamics.

Contribution

It provides new X-ray observational data and analysis of wind collision zones in these long-period massive star systems, enhancing understanding of their shock physics.

Findings

X-ray emission varies with orbital phase.

X-ray flux inversely correlates with orbital separation.

Insights into shock properties and plasma conditions.

Abstract

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.