Stars emit electromagnetic radiation between ULTRAVIOLET and INFRARED
A SPECTOGRAPH analyses frequencies of a beam of light
Absorption spectra is COLOURED with BLACK lines. this is where the frequencies are missing. Atoms in the star have absorbed the light at this frequency.
Absorption in the sun & other stars.
Different temp = different particles are able to absorb light. So even the sun is mainly H & He, they don't show because they can't absorb light at temp. of sun.
When the atoms, molecules and ions around stars absorb electromagnetic radiation, they are raised to higher energy states called excited states. The particles can lose their extra energy by emitting radiation. This results in an emission spectra.
The emissions spectra is BLACK with COLOURED lines. This is where the frequencies have been emitted.
The lines for the emission spectrum for one element correspond with the lines on the absorption spectrum for that element to form one continuous spectrum.