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Topic: Fraunhofer lines

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	Joseph Von Fraunhofer
		Fraunhofer, now an orphan, left his hometown in 1799 to move in with Philipp Anton Weichselberger, court mirror maker and decorative glass cutter, to be his apprentice [4].
		The lines Fraunhofer observed from stars are a result of absorption of light by the elements in the atmosphere of those stars.
		Fraunhofer investigated the properties of diffraction in the “far field” using a diffraction grating (instead of a prism, which adds complications due to varying index of refraction with wavelength).
	www.u.arizona.edu /~kennelly/finaldraft.htm (1224 words)

	Joseph von Fraunhofer
		In 1812-1814 Fraunhofer was fully engaged in the design of achromatic objective lenses for telescopes, which required the accurate determination of refractive indices of optical glasses.
		Although he did notice and comment upon the wavelength coincidence between his D line and a prominent line in laboratory flame spectrum (now known to be due to Sodium), he did not pursue the matter much further.
		Fraunhofer did succeed, in 1817, in designing an achromatic objective lense; with minor modifications, his design is still in use today.
	www.hao.ucar.edu /Public/education/bios/fraunhofer.html (364 words)

	Fraunhofer lines - Wikipedia, the free encyclopedia
		In physics and optics, the Fraunhofer lines are a set of spectral lines named for the German physicist Joseph von Fraunhofer (1787--1826).
		The lines were originally observed as dark features in the optical spectrum of the Sun.
		Because of their well defined wavelengths, Fraunhofer lines are often used to characterize the refractive index and dispersion properties of optical materials.
	en.wikipedia.org /wiki/Fraunhofer_lines (387 words)

	frauenhofer
		Among Fraunhofer's achievements were the invention of the diffraction grating, a detailed study of the solar spectrum, and production of the finest telescopes available in his day.
		Dark lines in the absorption spectrum of solar radiation due to absorption by gases in the outer portions of the sun and in the earth's atmosphere.
		Fraunhofer lines are designated by letters, as the K-line, or by wavelength, as the 4046-angstrom line of iron.
	www.calstatela.edu /faculty/kaniol/a360/fraunhofer.htm (392 words)

	MIT Spectroscopy Lab - History
		Fraunhofer, born near Munich in 1787, extended Newton's discovery by observing that the sun's spectrum, when sufficiently dispersed, was crossed by a large number of fine dark lines (1814), now known as Fraunhofer lines.
		Fraunhofer's achievements are all the more impressive, considering that he died at the early age of 39.
		From this, Kirchhoff and R. Bunsen explained that the Fraunhofer lines in the sun' s spectrum were due to absorption of the continuous spectrum emitted from the hot interior of the sun by elements at the cooler surface.
	web.mit.edu /spectroscopy/history/history-classical.html (798 words)

	ORRERY: The Solar Spectrum
		Fraunhofer (1817) rediscovered them, and noted some were not present in stars - but other stars had more.
		Brewster (1836) noted that the lines altered with the elevation of the sun.
		There are similar absorption lines in the other regions of the electromagnetic spectrum.
	www.harmsy.freeuk.com /fraunhofer.html (71 words)

	Joseph von Fraunhofer Biography \| World of Invention
		Though unhurt, Fraunhofer was trapped beneath the wreckage, prompting a large community rescue operation; in fact, the Elector of Bavaria himself was drawn to the scene.
		He also discovered that the light from the moon and the planets displayed the same line pattern as the sun, while other bright stars possessed individual spectral "signatures" (this is actually a logical conclusion, since the light from these bodies is simply reflected sunlight, but other stars generate their own light).
		All of this was unknown to Fraunhofer himself, and was left for Gustav Kirchhoff (1824-1887) to explain in 1859.
	www.bookrags.com /biography/joseph-von-fraunhofer-woi (820 words)

	Fraunhofer line concept from the Astronomy knowledge base (Site not responding. Last check: 2007-11-06)
		A band (6 facts) - One of about a dozen of the strongest Fraunhofer lines seen in the Solar spectrum, the A band at 7600 angstoms is due to telluric lines of molecular oxygen in the Earth's atmosphere.
		D line (2 kinds, 11 facts) - Spectral line of neutral sodium, also the strongest interstellar line.
		E line (4 facts) - Spectral line consisting of a blend of Fe I and Ca I. G band (6 facts) - A band of CH.
	www.site.uottawa.ca:4321 /astronomy/Fraunhoferline.html (243 words)

	Sun - Printer-friendly - MSN Encarta
		Each chemical element produces a unique set of lines, and the presence of these lines shows that a particular element is present in the stellar photosphere.
		Absorption lines in the Sun’s spectrum show that hydrogen is by far the most abundant element in the Sun.
		The Fraunhofer lines designated A and B actually have nothing to do with the composition of the Sun.
	encarta.msn.com /text_761562112___21/Sun.html (3015 words)

	Solar Physics: 1800 to 1999
		Fraunhofer pursued the matter mainly because he saw the possibility of using the lines as wavelength standards to be used to determine the index of refraction of optical glasses.
		Other physicists, however, were quick to realize that the Fraunhofer lines could be used to infer properties of the solar atmosphere, as similar lines were being observed in the laboratory in the spectrum of white light passing through heated gases.
		The dashed line is the Wolf sunspot number, showing the rise and fall of the solar cycle.
	www.hao.ucar.edu /Public/education/Timeline.D.html (3990 words)

	[No title]
		He observed the multitude of lines, labelled the 10 brightest with letters, and measured precise positions for 350 lines, which have become known as the Fraunhofer lines in the solar spectrum.
		Burning a carbon arc, he noted the orange emission lines it produced at the location of the D lines in sunlight; and the orange absorption lines seen in the continuous spectrum of the glowing arc tips.
		The emission line from the tube was slightly offset from the absorption line of the star, by 1.09 Angstroms, and after correcting for the earth's rotation around the sun, he concluded that Sirius was receding by 29 miles per second, although an accurate value is 5 miles per second.
	home.europa.com /~telscope/histspec.txt (5290 words)

	Coat-of-arms of Bavarian physicist Joseph von Fraunhofer (1787-1826) - Numericana (Site not responding. Last check: 2007-11-06)
		Studied the Fraunhofer lines in the solar spectrum (1813).
		The dark lines in a stellar spectrum correspond to definite frequencies absorbed by chemical substances in the outer layers of the star.
		The presence of dark lines in the solar spectrum was first noticed in 1802 by the English chemist William Hyde Wollaston (1766-1828).
	home.att.net /~numericana/arms/fraunhofer.htm (181 words)

	Joseph von Fraunhofer Biography \| World of Physics
		Fraunhofer initiated the field of spectrum analysis with his study of optics, along with his interest in designing achromatic objective lenses for telescopes.
		Fraunhofer, however, was interested in the spectral lines because they could be used as wavelength standards to determine the index of refraction of optical glasses.
		By measuring the wavelength of more than 300 of the lines he saw in his solar spectrum, Fraunhofer discovered that the lines' relative positions in the spectra of elements are constant.
	www.bookrags.com /biography/joseph-von-fraunhofer-wop (557 words)

	Fraunhofer Absorption Lines (Text) (Site not responding. Last check: 2007-11-06)
		In certain circumstances, the wavelengths corresponding to the Fraunhofer absorption lines in the stellar continuum may be preferred for communications because they may slightly increase the obtainable signal-to-noise ratio.
		The typical absorption profile of this line from a quiet Sun is such that the minimum intensity in the dark line is about 20% of the intensity of the general continuum.
		The so-called dark line is really not that dark, and in the case of the H line, amounts to a contrast ratio of only 5:1.
	www.coseti.org /9008-075.htm (187 words)

	Week 7 Readings (Site not responding. Last check: 2007-11-06)
		Instead of observing the spectrum directly with his eye, Fraunhofer positioned a theodolite in the path of the refracted beam, thus creating an observing and measuring instrument that was the prototype of the modern spectroscope.
		Like Wollaston, Fraunhofer found a narrow slit to be the best aperture through which to view an extended light source, but he was concerned that diffraction effects at the edge of the aperture might influence the appearance of the spectral lines.
		Since its discovery, the chief nebular line had gained wide acceptance as a signature of certain classes of nebulae, but because it is located tantalizingly close to spectral lines associated with several terrestrial elements, attempts to explain the physical and chemical processes producing the line fueled a vigorous controversy.
	eee.uci.edu /clients/bjbecker/ExploringtheCosmos/week7a.html (9316 words)

	A band Comparison Table (Site not responding. Last check: 2007-11-06)
		Absorption line in the spectrum of the Sun, studied by Fraunhofer in 1814.
		Each line represents an increment of energy due to a change in the rotational state of the molecule.
		One of about a dozen of the strongest Fraunhofer lines seen in the Solar spectrum, the A band at 7600 angstoms is due to telluric lines of molecular oxygen in the Earth's atmosphere.
	www.site.uottawa.ca:4321 /astronomy/Aband_table.html (198 words)

	Search Results for "D-Lines" (Site not responding. Last check: 2007-11-06)
		In early attempts at the notation of plainsong, a single line was drawn,...
		...Contour lines are drawn on maps with a uniform interval of vertical distance separating them (usually 10, 20, 50, or 100 ft on American maps) and thus outline the...
		...Zeeman effect, splitting of a single spectral line (see spectrum) into a group of closely spaced lines when the substance producing the single line is subjected to...
	www.bartleby.com /cgi-bin/texis/webinator/65search?query=D-Lines (282 words)

	Fraunhofer Lines - Search Results - MSN Encarta
		Fraunhofer Lines, dark lines identifiable in the absorption spectrum of the Sun, which were first observed by W. Wollaston in 1802 and later...
		Different elements, however, sometimes give rise to lines that are...
		- dark lines in Sun's spectrum: narrow dark lines in the Sun's spectrum, caused mainly by absorption in the cooler outer layers of the Sun's atmosphere
	uk.encarta.msn.com /Fraunhofer_Lines.html (143 words)

	Satellite Group: History
		One important step forward in the understanding of the Fraunhofer lines was the discovery of the physical principles of absorption and emission in 1859 by the very fruitful collaboration of the physicist Gustav R. Kirchhoff (1824 - 1887) and the chemist Robert W. Bunsen (1811 - 1899) in Heidelberg.
		First the Fraunhofer lines are (mainly) removed by dividing the measurement by a spectrum of direct sun light.
		The correction of the ‘filling-in’ of the solar Fraunhofer lines by atmospheric Raman- scattering [Grainger and Ring, 1962; Solomon et al., 1987a; Wagner et al., 2001a].
	satellite.iup.uni-heidelberg.de /index.php/History/history/0 (3104 words)

	Spectral Analysis - What Do Spectra Tell Us? - Introduction
		The studies of the Solar spectrum (Joseph Fraunhofer is the most famous, and probably also the most important, early contributor to this field), however, revealed absorption lines (dark lines against the brighter continuum).
		An emission line at 587.6 nm was first observed in the Solar corona during the eclipse of 1868 August 18th, although the precise wavelength was difficult to establish at the time (due to the short observation using temporary set-ups of instruments transported to Asia).
		She applied the up-to-date theory of spectral line formation, and found that the chemical compositions of stars were probably all similar, the temperature being the important factor in creating their diverse appearances.
	imagine.gsfc.nasa.gov /docs/science/how_l1/spectral_what.html (1056 words)

	Brief History of Light and Spectra
		Five lines were reported as being on the boundries between two colors, but two lines were within the color boundries (specifically yellowish-green and blue).
		It was suggested that the dark lines are due to the presence of gases on the sun.
		However, with the lithium flame, a new line appeared between the B and C lines (remember these were labeled by Fraunhofer) that could not be associated with any of the known dark lines.
	dbhs.wvusd.k12.ca.us /webdocs/Electrons/Spectrum-History.html (3357 words)

	Joseph von Fraunhofer - Wikipedia, the free encyclopedia
		In 1814, Fraunhofer invented the spectroscope, and discovered 574 dark lines appearing in the solar spectrum.
		These were later shown to be atomic absorption lines, as explained by Kirchhoff and Bunsen in 1859.
		These lines are still sometimes called Fraunhofer lines in his honour.
	en.wikipedia.org /wiki/Joseph_von_Fraunhofer (438 words)

	Solar Physics Department
		It was aimed at the study of the photospheric motion field, the damping constant, the asymmetry and shifts of the Fraunhofer lines, the mechanisms of their formation, and empirical determination of solar oscillator strengths.
		The Kyiv program for determining oscillator strengths of Fraunhofer lines from the optical solar spectrum recently resulted in a compilation of solar gf-values for 1958 lines of about 40 chemical elements (Gurtovenko and Kostik, 1989, Kostik, Shchukina and Rutten, 1996).
		Among these lines are the FeI lines used in polarimetry; 12 microm Mg I lines - indicators of solar magnetism; alkali lines used in helioseismology; lines of neutral lithium that is a key element in studying the history of the universe, nucleosynthesis, and stellar evolution.
	www.mao.kiev.ua /sol/sol_w3.html (485 words)

	The Classification of Stellar Spectra (Site not responding. Last check: 2007-11-06)
		Joseph Fraunhofer made a more careful set of observations of the solar spectrum in 1814 and found some 600 dark lines, and he specifically measured the wavelength of 324 of them.
		Important lines are the hydrogen Balmer lines, lines of neutral and singly ionized helium, iron lines, the H and K doublet of ionized calcium at 396.8 and 393.3 nm, the G band due to the CH molecule, the 422.7 nm neutral calcium line, several metal lines around 431 nm, and the lines of titanium oxide.
		The broadness of the lines also indicates that the material observed may be from high velocity gases streaming away from the star, with the range of velocities smearing out the observed lines.
	www.star.ucl.ac.uk /~pac/spectral_classification.html (1913 words)

	Identifying Lines in the Solar Spectrum
		Absorption lines in the solar spectrum were first noticed by an English astronomer in 1802, but it was a German physicist, Joseph von Fraunhofer, who first measured and cataloged over 600 of them about 10 years later.
		These lines are now known collectively as the "Fraunhofer lines." In the 1800's, scientists did not know that these lines were chemical in origin.
		Once the pattern of the lines of a particular element have been observed in the laboratory, it is possible to determine whether those elements exist elsewhere in the universe simply by pattern matching the absorption lines.
	www.astro.washington.edu /labs/clearinghouse/labs/Solarspec/sunspec.html (527 words)

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