Astronomers Analyze Electromagneti Emissions of Stars and Constellations

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In order to glean information about stars, astronomers analyze electromagnetic emissions, or the light, that reaches Earth. A spectroscope is basically a device that focuses a beam of light through a prism, which divides the light into characteristic colors that can then be seen using an eyepiece or screen. The resulting spectrum is used to determine the chemical composition of stars. The lines on the spectrum, or spectral lines, are associated with known elements. In 1868, an unknown element was discovered and given the name helium. It was almost thirty years before the element would be detected on Earth (McMillan, 2011).
The accepted classification scheme is a combination of two, the Harvard system types stars based on surface temperature and the MK system, which types stars based on luminosity. In the 1880s, the Henry Draper catalogue of stars was being compiled at the Harvard College Observatory. During this time, more types of stars were discovered and labeled using letters of the alphabet based on hydrogen spectral line strength. Eventually, the types were listed in non-alphabetical order based on surface temperature, resulting in the O, B, A, F, G, K, M classification system. This order of stellar types ranges from O, bluish-white stars with surface temperatures from twenty-five thousand degrees Kelvin to fifty thousand degrees Kelvin, to M, red stars with surface temperatures of approximately three thousand degrees Kelvin. The Sun is a type G star…

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