Fig. 13.
Sections of marginally trapped tori (toroidal minimal surfaces, at the same time) in ring systems with the |$(x,z)$|-plane for |$R/GM=0.05$|, |$0.10$|, |$0.15$|, |$0.20$|, |$0.25$|, |$0.30$|, |$0.35$|, |$0.40$|, and |$0.41413$|. For |$R/GM\ge 0.41414$|, a marginally trapped torus cannot be found. Compare with Fig. 8.