Vol. 594
In section 7. Stellar structure and evolution

ξ Tauri: a unique laboratory to study the dynamic interaction in a compact hierarchical quadruple system

This paper presents a comprehensive study of ξ Tauri, which is a unique and rare close-quadruple stellar system, where dynamical interactions among its members occur on human timescales. It has favourable orbital geometry and luminosity ratios between its components that allow the determination of physical properties of the system and its components with high precision. This study presents a large series of spectroscopic, photometric (including space-borne) observations, and long-baseline optical and infrared spectro-interferometric observations. The authors use both a set of observation-specific models and an N-body model to determine the properties of this complex system. Using perturbation theory, the authors show that the prominent secular and periodic dynamical effects are explainable with a quadrupole interaction between the inner and intermediate orbits. They have constrained the basic properties of all components, including the especially challenging members of the inner triple subsystem, and also provided a distance measurement that is independent of photometry. This systems is thus an excellent test bed for models of formation and evolution of hierarchical systems.