Emission line diagnostics

Emission line diagnostics are techniques scientists use to analyze the light emitted by astronomical objects, like stars or galaxies, to understand their physical properties. When matter in space is energized—by heat, radiation, or magnetic activity—it emits specific colors (wavelengths) called emission lines. By studying these lines' brightness and patterns, researchers can determine temperature, density, composition, and ionization states of the gas. This helps reveal the conditions, processes, and evolution of celestial objects, offering insights into the universe’s complex environments without needing direct contact.