Despite the vast distances that separate us from the stars, we know a lot about them. Astronomers can extract an amazing amount of information from starlight.
Remember that starlight is composed of many different wavelengths. When starlight is separated into its component wavelengths, the resulting spectrum holds many clues about the stars. Spectroscopy is the analysis of spectra (or spectrums). Spectra are of three basic types, each produced under different physical conditions.
Describe the appearance of each type of spectrum illustrated in Figure 3.3.
(a) Continuous spectrum: a continuous array of all the rainbow colors.
(b) Emission, or bright-line, spectrum: a pattern of bright-colored lines of different wavelengths.
(c) Absorption, or dark-line, spectrum: a pattern of dark lines across a continuous spectrum.
Note: Modern astronomers work with spectra as graphs of intensity versus wavelength (Figures 3.8, 3.9, 6.22b).
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