Absorption lines in the spectrum of a star primarily tell us about the elements found in the star. When light from a star passes through its atmosphere, specific wavelengths of light are absorbed by elements in the star's outer layers, creating dark lines in the spectrum at those wavelengths. By analyzing the absorption lines, astronomers can identify the presence of various elements and compounds and infer the star's composition.
While absorption lines can also provide indirect information about the star's temperature (through the type and strength of the lines), they are not directly used to determine the age or brightness of the star. Therefore, the best answer is that absorption lines indicate the elements found in the star.
2 answers