Figure 14.

The asymmetry of eclipses given by the proxy Δf_E for the B1957+20 system due to orbital sweep-back of a parallel-wind shock, as a function of injected velocity and constant wind acceleration a_wind for a fixed shock length L_z = 1 downstream from the companion. Horizontal cuts depict the eclipse asymmetry Δf_E varying the a_wind at a fixed injection velocity, while vertical cuts correspond to Δf_E as a function of v_inj. The white region corresponds to the portion of the parameter space not allowed by the radio results of Ryba & Taylor (1991); here either the asymmetry of eclipses or the total eclipse fraction are too large even at the lowest frequencies. Larger speeds and accelerations reduce eclipse asymmetry. The orbital speed of the companion is shown as the blue line and varies with inclination due to observed pulsar mass function for a fixed mass ratio q = 69.2.