Optical Identification of Binary Pulsars: Implications for Magnetic Field Decay in Neutron Stars1

We report the discovery of the optical counterparts of two binary pulsar systems-0655+64 and 0820+02. In accordance with stellar evolution scenarios we find the optical counterparts to be white dwarfs. The existence of a cool and therefore old white dwarf in the 0655 + 64 system contradicts the standard hypothesis of exponential decay of magnetic fields in neutron stars. We resolve this contradiction by hypothesizing that the magnetic field in neutron stars consists of two components-an exponentially decaying field and a steady field. The former probably resides in the crust and the latter perhaps in the core: The consequences of this hypothesis for the lifetimes of millisecond pulsars, binary pulsars, and galactic bulge X-ray sources are discussed. Subject headings: pulsarsstars: binariesstars: white dwarfs