We analyze observations from the Chandra X-ray Observatory of the southeast knot of the Cygnus Loop supernova remnant .
In this region , the blast wave propagates through an inhomogeneous environment .
Extrinsic differences and subsequent multiple projections along the line of sight rather than intrinsic shock variations , such as fluid instabilities , account for the apparent complexity of the images .
Interactions between the supernova blast wave and density enhancements of a large interstellar cloud can produce the morphological and spectral characteristics .
Most of the X-ray flux arises in such interactions , not in the diffuse interior of the supernova remnant .
Additional observations at optical and radio wavelengths support this account of the existing interstellar medium and its role in shaping the Cygnus Loop , and they demonstrate that the southeast knot is not a small cloud that the blast wave has engulfed .
These data are consistent with rapid equilibration of electron and ion temperatures behind the shock front , and the current blast wave velocity v _ { bw } \approx 330 { km s ^ { -1 } } .
Most of this area does not show strong evidence for non-equilibrium ionization conditions , which may be a consequence of the high densities of the bright emission regions .