Valzquez, et al. A composite image of the Cygnus Loop H courtesy of Nancy Levenson. The Northeast Filament is a classic non-radiative filament. A spherical cloud is being struck from the left by a planar shock. Displayed is a 3-D projection of log density at times equal to 0.5, 2.0 and 4.5 times the shock crossing time.
Shock is incident from the right.