![]() From these data and for this spectral range, the correlated color temperature (CCT) is 5470 K. Some of the characteristic Fraunhofer lines and their corresponding elements are indicated for the extended visible spectrum (highlighted area in the graph).įor photometry and colorimetry, standard measurements are usually carried out in the range 360 - 830 nm. Solar Spectral Irradiance measured with a calibrated optical spectrometer mounted with a cosine corrector. The major Fraunhofer lines, and the elements they are associated with, are shown in the following table: The photosphere gas has lower temperatures than gas in the inner regions, and absorbs a little of the light emitted from those regions. In the Sun, Fraunhofer lines are a result of gas in the photosphere, the outer region of the sun. Absorption lines are dark lines, narrow regions of decreased intensity, that are the result of photons being absorbed as light passes from the source to the detector. ![]() The Fraunhofer lines are typical spectral absorption lines. Some of the observed features were identified as telluric lines originating from absorption by oxygen molecules in the Earth's atmosphere. It was correctly deduced that dark lines in the solar spectrum are caused by absorption by chemical elements in the solar atmosphere. Modern observations of sunlight can detect many thousands of lines.Ībout 45 years later, Kirchhoff and Bunsen noticed that several Fraunhofer lines coincide with characteristic emission lines identified in the spectra of heated elements. He mapped over 570 lines, designating the principal features (lines) with the letters A through K and weaker lines with other letters. In 1814, Fraunhofer independently rediscovered the lines and began to systematically study and measure the wavelengths where these features are observed. In 1802, the English chemist William Hyde Wollaston was the first person to note the appearance of a number of dark features in the solar spectrum. ĭiscovery Solar spectrum with Fraunhofer lines as it appears visually. ![]() The lines were originally observed as dark features ( absorption lines) in the optical spectrum of the Sun (white light). In physics and optics, the Fraunhofer lines are a set of spectral absorption lines named after the German physicist Joseph von Fraunhofer (1787–1826). ![]() The "spectrum of blue sky" presents across 450–485 nm, the wavelengths of the color blue. Dips in intensity are observed as dark lines (absorption) at the wavelengths of the Fraunhofer lines, (e.g., the features G, F, b, E, B). Spectral lines in the Sun's spectrum Wavelengths of the visual spectrum, 380 to about 740 nanometers (nm). ![]()
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