Evolution of supernova remnants in the interstellar medium with a large-scale density gradient

The results of the 2D modelling of Supernova remnant (SNR) RCW 86 are given. Models of this remnant, which for the first time interpret the anisotropy of surface brightness as a result of the evolution of adiabatic SNR in the interstellar medium with a large-scale gradient of density, are considered. Estimations on the basic characteristics of RCW 86 and the surrounding medium which follow from these models are found. It is shown that the observed surface brightness distribution of RCW 86 may be obtained in the both proposed up till now models with different initial assumptions: one about a Supernova explosion in 185 A.D. and another about an explosion in the OB-association. In order to obtain the observational contrast of surface brightness it is necessary to have a medium with the characteristic scale of nonuniformity 11 pc if the age of RCW 86 is 1800 years or 20 − 25 pc when the SNR is distant from us on 2.8 kpc. The preshock density contrast between the southwestern and northeastern parts of RCW 86 is in range 3.5 − 4.5.