Fraunhofer lines

Fraun·ho·fer lines

F0302400 (froun′hō′fər)pl.n. A set of several hundred dark lines appearing against the bright background of the continuous solar spectrum and produced by absorption of light by the cooler gases in the sun's outer atmosphere at frequencies corresponding to the atomic transition frequencies of these gases.

[After Joseph von Fraunhofer (1787-1826), German physicist.]

Fraunhofer lines

(German ˈfraunhoːfər) pl n (Anatomy) a set of dark lines appearing in the continuous emission spectrum of the sun. It is caused by the absorption of light of certain wavelengths coming from the hotter region of the sun by elements in the cooler outer atmosphere[named after J. von Fraunhofer (1787–1826), German physicist]

Fraunhofer lines

Dark lines seen on the Sun and other stars, named after their 1814 Bavarian discoverer.

Translations

righe di Fraunhofer

Fraunhofer lines

(froun`hôfər): see sunsun,
intensely hot, self-luminous body of gases at the center of the solar system. Its gravitational attraction maintains the planets, comets, and other bodies of the solar system in their orbits.
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Fraunhofer lines

(frown -hoh-fer) Absorption lines in the solar (photospheric) spectrum, first studied in detail by Joseph von Fraunhofer in 1814. He cataloged over 500 lines and labeled the more striking ones with letters. Over 25 000 lines have now been identified. The most prominent lines at visible wavelengths are due to the presence of singly ionized calcium, neutral hydrogen, sodium, and magnesium; many weaker lines are due to iron. The strength of a particular line depends not only on the quantity of the element present but also on the degree of ionization and level of excitation of its atoms. By isolating an individual strong line it is possible, by virtue of its residual intensity due to the reemission of radiation in the chromosphere, to observe the chromosphere in the light of the element concerned. See spectroheliogram. See also D lines; H and K lines; photosphere.

Fraunhofer Lines

absorption lines in the solar spectrum. Fraunhofer lines were first observed in 1802 by the British physicist W. H. Wollaston (1766–1828). They were detected and described in detail by J. von Fraunhofer in 1814 and were later correctly explained by G. R. Kirchhoff.

More than 20,000 Fraunhofer lines have been observed in the

Table 1. Some Fraunhofer lines
Symbol for line	Wavelength (microns)	Chemical element
A ...............	0.761	0
B ...............	0.687	0
C ...............	0.656	H_α
D ...............	0.589	Na
E ...............	0.527	Fe
F ...............	0.486	H_β
G ...............	0.431	Ca
H₁ ...............	0.397	Ca
H ...............	0.393	Ca

infrared, ultraviolet, and visible regions of the solar spectrum; many have been identified with the spectral lines of known chemical elements. The most intense Fraunhofer lines in the visible region are given in Table 1.

Fraunhofer lines

[′frau̇n‚hōf·ər ‚līnz] (spectroscopy) The dark lines constituting the Fraunhofer spectrum.

Fraunhofer lines

ab·sorp·tion lines

the dark lines in the solar spectrum corresponding to wavelengths originally emitted by inner layers of the Sun but then absorbed by various elements present in gaseous form in cooler layers and in the Earth's atmosphere. Synonym(s): Fraunhofer lines

Fraunhofer lines

(frown′hōf″ĕr) [Joseph von Fraunhofer, Ger. optician, 1787–1826] Absorption bands or lines seen in a spectrum, caused by the absorption of groups of light rays in their passage through solids, liquids, or gases.

Fraunhofer,

Joseph von, German optician, 1787-1826. Fraunhofer lines - a number of the most prominent of the absorption lines of the solar spectrum.