What is the dominant spectral emission line from an emission nebula in visible light?

Question

Quizplus · Accepted Answer

The dominant spectral emission line from an emission nebula in visible light is the hydrogen alpha (Hα) line, which is represented as H_α. This occurs when electrons in hydrogen atoms make a transition from the second energy level to the first energy level, emitting a photon with a wavelength of 656.3 nm in the process. This is a common emission line in many types of nebulae, including H II regions, planetary nebulae, and supernova remnants.

What Is the Dominant Spectral Emission Line from an Emission