Activity in the Crab Nebula

Abstract

A series of 200-inch continuum and polarization plates of the Crab Nebula has been studied in con- nection with the activity discovered by Lampland and Baade. A number of sharply defined features near the center show changes which correspond to relativistic velocities, but there is also evidently subtler activity throughout the nebula. This activity is concentrated toward the northwest quadrant of the nebu- la, and is slower and less conspicuous with increasing distance from the center. The bright main wisp seems to be a permanent compressed region which moves as a whole in a reciprocating manner, but the other apparent motions may be regarded as propagating hydromagnetic disturbances. The continuous spectrum seems to be correlated with the activity in the sense that it is flatter (i e., a is smaller) close to the center where the activity is most violent, and steeper toward the edges of the nebula