Figure 1.

Schematic cross-sectional diagram of a “spider” MSP binary system, scale exaggerated for clarity, illustrating geometry and defining some variables and parameters used in this paper. The gray dotted curves depict differing thin-shell shock surface realizations for colliding momentum-dominated isotropic winds. In RBs and transitional objects in the rotation-powered state, the orientation of the shock is reversed such that the shock bows around the pulsar somewhat outside its light cylinder, with the definition of R₀ taken from the MSP in that case. Definitions of symbols are discussed in §2.1 and elsewhere.