SOME IMPLICATIONS OF PSR 1259-63

We estimate that the binary PSR 1259 - 63 consists of a M(ns) = 1.4 M. neutron star orbiting a M* = 20 M. Be star with orbital inclination sin (i) greater than or similar to 0.9 and pulsar period derivative P congruent-to 10(-15). Oscillations of the Be star excited by the close pericentric passages of the neutron star may produce an orbital period derivative of P0 approximately 10(-6), although the number is exponentially sensitive to the ratio of the stellar and pericentric radii. The tidally induced oscillations of the star can be detected as photometric fluctuations larger than 0.001 mag if P0 greater than or similar to 10(-8). The mass flux in the Be star wind is between 0.1 less than or similar to M8nu3 less than or similar to 1 where nu = 10(3)vu3 km s-1 is the wind velocity and M = 10(-8) M8 M. yr-1 is the mass flux. The upper limit is set by the observed limits on variations in the dispersion measure, and the lower limit is required for a reasonable stellar wind to produce the observed eclipse of the pulsar by free-free absorption. The existence of a coherent stellar wind to produce the absorption means that less than epsilon(c) less than or similar to 10(-2) M8nu3(-1)P-15(-1) of the pulsar spin-down energy can be coupled to the stellar wind for a pulsar spin-down rate of P = 10(-15) P15. If accretion onto neutron stars prevents pulsed radio emission, then the coupling must be greater than epsilon(c) greater than or similar to 10(-6) M8nu3(-3)P-15(-1) to prevent accretion in the range where the radio pulsar is seen. The neutron star disrupts part of the Be star disk during each pericentric encounter leading to dramatic variations in the emission-line profiles, particularly on the blueshifted side of the line. Except when the neutron star passes through the Be star's disk, this system should be a poor X-ray source, probably dominated by the coronal X-ray emission from the Be star. During the passage through the Be star disk the X-ray luminosity should approach levels typical of massive X-ray binaries for a period of about one week.