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In physics and optics, the Fraunhofer lines are a set of spectral lines named after the German physicist Joseph von Fraunhofer (1787–1826). The lines were originally observed as dark features (absorption lines) in the optical spectrum of the Sun. ==Discovery== In 1802, the English chemist William Hyde Wollaston〔Melvyn C. Usselman: (William Hyde Wollaston ) Encyclopedia Britannica, retrieved 31 March 2013〕 was the first person to note the appearance of a number of dark features in the solar spectrum.〔William Hyde Wollaston (1802) ("A method of examining refractive and dispersive powers, by prismatic reflection," ) ''Philosophical Transactions of the Royal Society'', 92: 365-380; see especially p. 378.〕 In 1814, Fraunhofer independently rediscovered the lines and began a systematic study and careful measurement of the wavelength of these features. In all, he mapped over 570 lines, and designated the principal features with the letters A through K, and weaker lines with other letters.〔Joseph Fraunhofer (1814 - 1815) ("Bestimmung des Brechungs- und des Farben-Zerstreuungs - Vermögens verschiedener Glasarten, in Bezug auf die Vervollkommnung achromatischer Fernröhre" ) (Determination of the refractive and color-dispersing power of different types of glass, in relation to the improvement of achromatic telescopes), ''Denkschriften der Königlichen Akademie der Wissenschaften zu München'' (Memoirs of the Royal Academy of Sciences in Munich), 5: 193-226; see especially pages 202-205 and the plate following page 226.〕 Modern observations of sunlight can detect many thousands of lines. About 45 years later Kirchhoff and Bunsen〔See: * Gustav Kirchhoff (1859) ("Ueber die Fraunhofer'schen Linien" ) (On Fraunhofer's lines), ''Monatsbericht der Königlichen Preussische Akademie der Wissenschaften zu Berlin'' (Monthly report of the Royal Prussian Academy of Sciences in Berlin), 662-665. * Gustav Kirchhoff (1859) ("Ueber das Sonnenspektrum" ) (On the sun's spectrum), ''Verhandlungen des naturhistorisch-medizinischen Vereins zu Heidelberg'' (Proceedings of the Natural History / Medical Association in Heidelberg), 1 (7) : 251-255.〕 noticed that several Fraunhofer lines coincide with characteristic emission lines identified in the spectra of heated elements. It was correctly deduced that dark lines in the solar spectrum are caused by absorption by chemical elements in the Solar atmosphere. Some of the observed features were identified as telluric lines originating from absorption by oxygen molecules in the Earth's atmosphere. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Fraunhofer lines」の詳細全文を読む スポンサード リンク
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