While comprising only a small fraction of the mass, what key role do the trace heavier elements play in nebulae?

Answer

They are responsible for the vibrant colors observed in emission nebulae

Although they make up a small percentage of the total mass, these heavier components are vital because they are responsible for generating the distinct colors seen when emission nebulae interact with ultraviolet light.

While comprising only a small fraction of the mass, what key role do the trace heavier elements play in nebulae?
SpaceastronomycompositionnebulaGases