What are stellar spectra used for?

Stellar spectra are used to determine the chemical composition, temperature, and motion of stars.

Stellar spectra, or the electromagnetic radiation emitted by stars, provide valuable information about the chemical composition, temperature, and motion of stars. By analysing the spectra, astronomers can determine the elements present in a star, as each element emits a unique set of spectral lines. This information can be used to classify stars into different spectral types, such as O, B, A, F, G, K, and M, based on their surface temperature.

The temperature of a star can also be determined from its spectrum, as the intensity of the radiation emitted by a star is related to its temperature. Cooler stars emit more radiation in the red part of the spectrum, while hotter stars emit more radiation in the blue part of the spectrum.

Stellar spectra can also be used to determine the motion of stars. The Doppler effect causes the spectral lines to shift towards the red or blue end of the spectrum, depending on whether the star is moving away or towards us. By measuring this shift, astronomers can determine the radial velocity of a star, which can be used to study its motion and orbit.

Overall, stellar spectra are a powerful tool for studying stars and understanding their properties and behaviour.