What two primary factors significantly dictate the structure and ultimate fate of an expanding supernova remnant bubble?

Answer

The energy released in the blast and the density/distribution of the surrounding material

The structure and lifespan are governed by the energy of the initial explosion, which sets the speed, and the density and distribution of the surrounding interstellar material, which dictates drag and shape.

What two primary factors significantly dictate the structure and ultimate fate of an expanding supernova remnant bubble?
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