Neutron stars are the result of core collapse during supernova explosions. They are compact objects with masses comparable to 1 to 2 suns, but with radii of about 20 km. Their principal constituents are neutrons, and their interiors are believed to have superconducting characteristics. Furthermore, they usually possess extreme magnetic fields (ca. 1012 times as strong as the earth's magnetic field). Some radiate in a pulsating fashion and are known as pulsars. When neutron stars accrete matter from a close companion star or from the interstellar medium (as many stars do), highly energetic events ensue because of the deep gravitational well into which the matter falls. The results are frequently the emission of X- and gamma-rays, and the gradual evaporation of a nearby stellar companion by the irradiation with high energy photons. The Principal Investigator proposes to study theoretically six topics related to neutron star physics: 1. Gamma rays from solitary neutron stars; 2. gamma ray emission from accreting X-ray pulsars; 3. X- and gamma-rays from low mass binaries; 4. evolution of low mass X-ray binaries; 5.evaporation of very light companions in close radio-pulsar binaries; and 6. flux tube expulsion from neutron star superconducting cores. Dr. K. S. Cheng of Australia has been and continues to be a collaborator. The proposed work is a continuation of research previously funded by NSF.
