Schematic illustration of the observations and competing scenarios for HR 6819

Schematic illustration of the observations and competing scenarios for HR 6819. Sizes and distances are not to scale. Top: spectroscopic observations. Middle: original scenario, with a giant B star orbiting a black hole, and a rapidly-spinning Be star further away. Bottom: alternative scenario without a black hole,with a stripped B star thst is less massive than the Be one. Note that the spectral lines of the Be star do wobble very slightly (not shown here).