How do Emission Nebulae (H II Regions) generate their characteristic glow?
Answer
Ionization of hydrogen gas by embedded hot, massive stars.
Emission Nebulae, also termed H II Regions, are characterized by their ability to generate their own visible light. This luminescence stems from the intense ultraviolet radiation emitted by very hot, massive stars situated within or immediately adjacent to the cloud. This high-energy radiation strips electrons from the hydrogen atoms, ionizing the gas. As these ions recombine or cascade through energy levels, they emit light at specific spectral wavelengths, frequently manifesting as a reddish glow due to the dominant hydrogen content.
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