What technique do astronomers use to determine a star's elemental makeup by analyzing its emitted light?

Answer

Analyzing absorption lines in the spectrum

By examining which specific wavelengths of light are absorbed by cooler outer layers of the star, creating dark lines in the spectrum, scientists can map the elements present.

What technique do astronomers use to determine a star's elemental makeup by analyzing its emitted light?
Elementastronomyhydrogenstarhelium