SUPERNOVA-REMNANTS IN PLANE-STRATIFIED MEDIA - PREDICTIONS FOR H-ALPHA-EMITTING REGIONS

Numerical models for the time-dependent evolution of adiabatic supernova remnants in plane-stratified media are presented. These models approximate SNR evolution in the density distributions found near to the edges of dense molecular clouds or diffuse stellar wind bubbles. Use of a simple T-1/2 cooling law enables cooling surfaces within the remnants to be identified and their Halpha emission estimated. Projection of this emission on to the plane of the sky at a variety of angles of inclination, together with a consideration of the kinematics, allows comparisons with observed remnants to be made. It is found that the phenomenon of fast Halpha emission, as observed in the Cygnus Loop and N49 and N63 in the Large Magellanic Cloud, can be easily explained as a consequence of supernova remnant evolution in regions having high density contrasts.