What three properties of stars can astronomers determine by analyzing the spectrum of the stars light?
My list of three was:
- Chemical composition
- Relative motion
Chemical composition can be determined from emission or absorption lines in the spectrum.
Temperature can be measured based on the peak of the black body radiation, which ranges across a wide range of frequencies.
Relative velocity can be measured by the red or blue shift of the emission or absorption lines.
Apart from these three, the spectrum can be used to help determine:
One interesting factor is how much the emission lines or absorption lines are spread. This might indicate a surrounding protoplanetary disc or suchlike.