Question

List 4 things we can learn about a star using spectroscopy.

Answer 1

We can find out following properties of stars using spectroscopy

1.RIGHTNESS. This is not a fundamental property, but a combination of the luminosity and distance to a star (and in some cases also dependent on the amount of absorption in the direction of a star).

1. DISTANCE. From trigonometric and spectroscopic parallaxes. Determining distances to stars is how we figure out the scale of things in the Galaxy and is CRUCIAL to understanding stars because we can use the inverse square law for light dimming along with apparent brightness of stars to figure out how much energy is being produced and radiated away.
2. LUMINOSITY. This is the amount of energy generated in the star and released as electromagnetic radiation.
3. RADIUS ``Size''. From Stephan's Law.
4. CHEMICAL COMPOSITION. From the absorption line spectra. This one is tied up in a semi-complicated way with the next one.
5. Temperature. We have talked about Wien's Law and using colors to derive stellar temperatures, but, there are some complications. To REALLY get to surface temperatures of stars, we need to learn about and understand stellar Spectral Types.