Explain why color is a measure of a star's temperature. Blackbodies radiate according to their temperature. Stars are relatively good blackbodies, so the colors radiated by a star indicate its temperature. Name at least three characteristics of a star that can be determined by measuring its spectrum. Explain how you would use a spectrum to determine these characteristics.
Stellar temperature is indicated from the color ratios of the spectrum.
The radial motion of the star can be determined from the Doppler shift of absorption lines. The rotation rate of the star can be determined from the breadth of the absorption lines. The materials present in the atmosphere of the star can be determined from the absorption spectra. The gas density of the stellar atmosphere can be derived from the spectral lines. Low density stellar atmospheres allow ions to exist for a longer period of time, so the lines of ionized species are stronger.