The glowing filaments of the Veil Nebula are composed of the original star's matter mixed with what other material energized by the shockwave?

Answer

The swept-up interstellar gas

The debris cloud that constitutes the Veil Nebula is not solely composed of the matter ejected by the supernova explosion itself. As the immense shockwave races outward through the interstellar medium (ISM), it physically sweeps up and incorporates the pre-existing, diffuse gas and dust that naturally fills the space between stars. The process involves the shockwave compressing and energizing this ambient interstellar material, causing it to glow intensely alongside the ejected stellar remnants. This constant incorporation of local material influences the nebula's long-term appearance as the structure continues its attenuation and deceleration phase within the Galactic ISM.

The glowing filaments of the Veil Nebula are composed of the original star's matter mixed with what other material energized by the shockwave?
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