Compound of four octahedra with rotational freedom

Compound of four octahedra with rotational freedom
TypeUniform compound
IndexUC10
Polyhedra4 octahedra
Faces8+24 triangles
Edges48
Vertices24
Symmetry grouppyritohedral (Th)
Subgroup restricting to one constituent6-fold improper rotation (S6)

This uniform polyhedron compound is a symmetric arrangement of 4 octahedra, considered as triangular antiprisms. It can be constructed by superimposing four identical octahedra, and then rotating each by an equal angle θ about a separate axis passing through the centres of two opposite octahedral faces, in such a way as to preserve pyritohedral symmetry.

Superimposing this compound with a second copy, in which the octahedra have been rotated by the same angle θ in the opposite direction, yields the compound of eight octahedra with rotational freedom.

When θ=0, all four octahedra coincide. When θ is 60 degrees, the more symmetric compound of four octahedra (without rotational freedom) arises. In another notable case (pictured), for a certain intermediate value of θ in which 24 of the triangles form coplanar pairs, the compound assumes the form of the compound of five octahedra with one of the octahedra removed.

References


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