Helium emits a pale yellow color when burned, particularly in a flame. However, when we talk about helium in terms of its spectral lines, it displays a unique set of spectral colors. In a spectrum, helium produces several lines, predominantly in the yellow, blue, and violet ranges.
To elaborate, when helium gas is ionized or excited, the electrons move to higher energy levels. As they return to their original states, they release energy in the form of light at specific wavelengths. The spectrum of helium shows prominent lines such as the yellow D lines at 587.6 and 588.9 nanometers, as well as lines in the violet and blue regions. This characteristic spectral pattern is crucial for identifying helium in stellar atmospheres.