Radio Pulsar B0950+08: Radiation in the Magnetosphere and Sparks above the Surface

We observed the nearby radio pulsar B0950+08, which has a 100% duty cycle, using the Five-hundred-meter Aperture Spherical Radio Telescope. We obtained the polarization profile for its entire rotation, which enabled us to investigate its magnetospheric radiation geometry and the sparking pattern of the polar cap. After we excluded part of the profile in which the linear polarization factor is low (less than or similar to 30%) and potentially contaminated by jumps in position angle, the rest of the swing in polarization position angle fits a classical rotating vector model (RVM) well. The best-fit RVM indicates that the inclination angle, alpha, and the impact angle, beta, of this pulsar, are 100.degrees 5 and -33.degrees 2, respectively, suggesting that the radio emission comes from two poles. We find that, in such RVM geometry, either the annular vacuum gap model or the core vacuum gap model would require that the radio emissions come from a high-altitude magnetosphere with heights from similar to 0.25 R LC to similar to 0.56 R LC, with R LC being the light cylinder radius. Both the main and interpulses' sparking points are located away from the magnetic pole, which could relate to the physical conditions on the pulsar surface.