Intensity of the 21 cm line of neutral hydrogen towards USco in the 7.4 km s⁻¹ velocity channel (left panel) and by-eye characterisation of the Hi structures across multiple velocity channels (right panel). Three groups of rings are apparent: the USco loop (black), which corresponds to the dominant loop in the channel map on theleft, and two smaller, tube-like structures (green and red) which are cospatial but separated in velocity space. The red and green rings might be a result of erosion of the Hi interface between the Sco–Cen superbubble and the local bubble, where the hot gas streaming through the hole ablates and accelerates the Hi.