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E.M. Splaver, D.J. Nice (Princeton University Physics Dept.), D.R. Lorimer (NAIC), D.G. Khechinashvili, G.I. Melikidze (J. Kepler Astronomical Center)
PSR B1957+20 spends about one hour of its 9.2-hour binary orbit in eclipse. For much of that time, the pulsar is completely obscured by its companion. But as the source moves in and out of invisibility during roughly half an hour of ingress and egress, its pulses, though weakened, show interesting fluctuations in arrival time. Using Arecibo timing data, we relate these disturbances to spatial variability in the free electron content across the eclipse region. We also examine pulse profiles at multiple frequencies for changes in polarization that could provide clues to the nature of the eclipse mechanism. Finally, as eclipse duration in some theories depends on whether the companion is a degenerate star, we compare current eclipse lengths with those of a decade ago.
The author(s) of this abstract have provided an email address for comments about the abstract: pulsar@pulsar.princeton.edu