Kinematics of the supernova remnant S147

Slit spectra have been obtained at 15 locations on the supernova remnant S147. They indicate a systematic expansion velocity of about 80 km/s. Substitution in a theoretical model gives a radius of 17 pc and a distance of 600 pc. Comparison of the appearance of emission features with radial velocities suggests that in S147 the sharp filaments are ropelike structures rather than sheets viewed edge-on. In accord with this view, the sharp features show high densities, as measured by the doublet. Finally, it is observed that the high-density regions do not have lower radial velocities than the low density regions. This is contrary to expectation if the observed filaments arise from the passage of a shock through interstellar density fluctuations.