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Unformatted text preview: The Sizes of Stars Chapter index in this window Chapter index in separate window This material (including images) is copyrighted! . See my copyright notice for fair use practices. All but a few stars appear as mere pinpoints in even the largest telescopes. They are much too far away to derive their diameters from measuring their angular diameters and distances. Eclipsing binaries are used to determine indirectly the diameters of stars. These are two stars orbiting each other in a plane that is parallel to your line of sight so you see their orbits edge-on. This means that one star will periodically cover up the other star. During the eclipse the total brightness measured for the binary will decrease. The amount of the dip in brightness depends on the luminosity and relative size of the two stars. A star's diameter is found from speed = (distance travelled)/(time it takes). The speed comes from the doppler shift and the time is the length of the eclipse. The distance travelled during the from the doppler shift and the time is the length of the eclipse....
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