In a Planetary Nebula, the Shell of Expelled Material Is

question 19

Multiple Choice

In a planetary nebula, the shell of expelled material is glowing intensely. What is the main source of energy for this glow?

• A) friction, as the atoms of the expelled shell rub against each other
• B) the explosion of the dying star
• C) ultraviolet radiation from the collapsing hot star at the center
• D) the fusion of hydrogen into helium in the nebula
• E) the change of electrons and protons into neutrons

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