A merlin observation of PSR B1951+32 and its associated plerion

In an investigative 16 hr L-band observation using the MERLIN radio interferometric array, we have resolved both the pulsar PSR B1951 +32 and the structure within the flat spectral radio continuum region, believed to be the synchrotron nebula associated with the interaction of the pulsar and its "host" supernova remnant CTB 80. The extended structure we see, significant at ∼4.5 σ, is of dimensions 2″.5 × 0″.75 and suggests a sharp bow-shaped arc of shocked emission, which is correlated with a similar structure observed in lower resolution radio maps and X-ray images. Using this MERLIN data as a new astrometric reference for other multiwavelength data, we can place the pulsar at one edge of the HST reported optical synchrotron knot, ruling out previously suggested optical counterparts and allowing an elementary analysis of the optical synchrotron emission that appears to trail the pulsar. The latter is possibly a consequence of pulsar wind replenishment, and we suggest that the knot is a result of magnetohydrodynamic (MHD) instabilities. These being so, it suggests a dynamical nature to the optical knot, which will require high-resolution optical observations to confirm.