Hα emission refers to a specific spectral line in the hydrogen atom that appears in the visible spectrum at a wavelength of approximately 656.3 nanometers. This emission line is commonly observed in astronomical phenomena, such as in the spectra of stars, nebulae, and galaxies. The presence and intensity of Hα emission can provide valuable information about the temperature, density, and composition of the emitting source. Researchers often study Hα emission to gain insights into the physical properties and dynamics of celestial objects, as well as to investigate processes such as star formation, supernova explosions, and accretion onto black holes.