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	Atomic Absorption and Emission Spectra
		Thus, emission spectra are produced by thin gases in which the atoms do not experience many collisions (because of the low density).
		The emission lines correspond to photons of discrete energies that are emitted when excited atomic states in the gas make transitions back to lower-lying levels.
		Emission or absorption processes in hydrogen give rise to series, which are sequences of lines corresponding to atomic transitions, each ending or beginning with the same atomic state in hydrogen.
	csep10.phys.utk.edu /astr162/lect/light/absorption.html (408 words)

	UVES sky emission spectrum
		This spectrum is the combination of airglow emission lines, telluric absorption lines and the solar spectrum due to scattered moonlight.
		The fluxed sky spectra are dominated by faint emission lines in the blue, and a rich emission line spectrum with both strong and faint lines in the red.
		Line blends which would be considered as resolved with a simple cursor-marked approach are still a blend for the Gaussian fit procedure unless two peaks are clearly separated.
	www.eso.org /observing/dfo/quality/UVES/pipeline/sky_spectrum.html (1734 words)

	NRAO Glossary
		Balmer lines: Emission or absorption lines in the spectrum of hydrogen that arise from transitions between the second and higher energy states of the hydrogen atom.
		Emission Line: A bright line in a spectrum caused by the emission of photons from atoms.
		OH Line: Dark absorption lines on an electromagnetic spectrum or the emission of photos by hydroxyl (OH) molecules (one atom of oxygen and one atom of hydrogen).
	www.nrao.edu /imagegallery/glossary.shtml (4257 words)

	Chapter 4, Section 1 (Site not responding. Last check: )
		The pattern of spectral emission lines is a property of the element hydrogen.
		They quickly observed an intriguing connection between emission and absorption lines: the absorption lines associated with a given gas occur at precisely the same wavelengths as the emission lines produced when the gas is heated.
		Once again, these lines are characteristic of the composition of the intervening gas—they occur at precisely the same wavelengths as the emission lines produced by that gas at higher temperatures.
	astronomy.nju.edu.cn /astron/at3/AT30401.HTM (1994 words)

	Emission and absorption lines
		Figure 8.3: Diagram illustrating emission and absorption lines: when light given off by hot gas is decomposed using a prism it is shown to be made up of colored lines (emission lines).
		After the discovery of emission and absorption lines scientist came to rely heavily on the fact that each element presents a unique set of lines: it is its inimitable signature.
		It was later shown that the coronium lines were in fact iron lines, which are clearly observable only in the extreme conditions present in the sun (one can also see them in the laboratory, it's just hard to do so).
	phyun5.ucr.edu /~wudka/Physics7/Notes_www/node107.html (507 words)

	Algorithms: Spectral line fits - SDSS DR3
		The first line fit is done when attempting to measure the object's emission line redshift.
		Line indices are invariant under transforming from observed to rest frame.
		Since the line fits are allowed to drift in wavelength somewhat, the exact precision of the lines are not important.
	www.sdss.org /dr3/algorithms/speclinefits.html (885 words)

	Galaxies and the Universe - Emission -Line Spectra (Site not responding. Last check: )
		This means that certain line ratios are fixed by statistical weights in the atoms - the ratio of photon numbers in the lines is the ratio of statistical weights, and the ratio of line intensities is this value modified by the ratio of frequencies.
		The line ratio is about 1000 at 6000 K, dropping to 100 at 14000 K. However, beware that a one-zone model is seldom appropriate; a small amount of hot gas may skew the results.
		Hydrogen or helium recombination lines are also frequently used to measure reddening; if the temperature is known (and a one-zone model is not too bad) they may be measured over an enormous wavelength range, but are frequently dominated by the tiny BLR or have highly velocity-composite profiles.
	www.astr.ua.edu /keel/galaxies/emission.html (2855 words)

	Spectrum of Betelgeuse Captured with a Prototype SBIG Spectrometer
		This technique is necessary if one attempts to measure the red shifts of galaxies of emission lines of quasars.
		Using the high resolution grating and the narrow slit the spectrograph is capable of resolving narrowly separated lines.
		The magnesium lines in the three stars shown in Figure 10 are separated by only 5.4 angstroms.
	www.sbig.com /sbwhtmls/spectrometer2.htm (894 words)

	The physics of quasars (Site not responding. Last check: )
		The defining characteristic of this class is the presence of emission lines due to the O VI doublet 3811, 3834 Å among the strongest lines in the spectrum.
		In addition, emission lines C IV 4658 Å and He II 4686 Å are also present and are usually of comparable intensity to the O VI lines.
		In the course of our analysis of the spectra of quasars, we have found that there are at least fourteen quasars whose emission line spectra (as observed, no redshift) belong to the O VI sequence.
	laserstars.org /V1979/emission.html (554 words)

	Spectra
		Emission lines are easy to produce in the laboratory simply by heating a low-density gas, allowing collisions to kick the electrons to higher energies.
		Emission lines are radiated by street lamps (the orange ones radiating sodium lines, the blue ones mercury lines), neon signs, and fluorescent bulbs.
		Hydrogen emission lines are radiated by a hot, thin hydrogen gas, and appear at the same wavelengths as the hydrogen absorption lines.
	www.astro.uiuc.edu /~kaler/sow/spectra.html (5900 words)

	News September 2002: More X-ray emission lines from XMM-Newton gamma ray bursts
		All previous reports of X-ray emission lines had been identified with iron, as would be expected if the X-rays were due to illumination of the stellar remnant by the gamma rays.
		It is clear that the power law is not a good fit to the data, while the fits to models including emission lines from Mg, Si, S, Ar, and Ca (thermal plasma model in d), or 5 emission lines with a power law (e) are good descriptions of the data.
		These results show that thermal X-ray emission, such as was reported earlier this year in Nature, is unlikely to be unique to that gamma ray burst.
	www.star.le.ac.uk /news/0902.html (1045 words)

	Emission Experiment from MeasureNet
		Before proceeding to the observation of line spectra from excited atoms, it is instructive to examine the white light emitted by an incandescent filament.
		Unlike the procedure for recording the emission spectrum of fluorescent lights, the emission of light from the flame is not steady.
		Examine this spectrum carefully to see whether any of the "extraneous" lines in the experimental H atom spectrum may be assigned to traces of oxygen present and therefore excluded from the analysis.
	www.oceanoptics.com /applications/emissionexperiment.asp (3122 words)

	Chapter 2, Section 5
		This particular pattern of spectral emission lines is a property of the element hydrogen—whenever we perform this experiment, the same characteristic emission spectrum is the result.
		The absorption lines appear at precisely the same wavelengths as the emission lines that would be produced if the gas were heated to high temperatures (see Figure 2.12).
		Almost all of the lines observed in the light received from extraterrestrial sources could be attributed to known elements (for example, many of the Fraunhofer lines in sunlight are associated with the element iron).
	wps.prenhall.com /wps/media/objects/610/625137/Chaisson/CH.00.002/HTML/CH.00.002.s5.htm (1449 words)

	Types of Stars - Spectral Lines (Site not responding. Last check: )
		Emission lines also depend on the temperature of a star; they only appear if a star is at the right temperature.
		Most elements absorb or emit light best at a certain temperature; therefore, at that temperature, their absorption or emission lines are strongest.
		If you are interested in learning where to find all the lines the SDSS software uses, you can find a table of all the lines.
	cas.sdss.org /dr3/en/proj/basic/spectraltypes/lines.asp (749 words)

	Visible light spectral emission lines from sodium in a flame
		Examining the emission and absorbtion lines of chemical elements in the spectra of stars and galaxies has greatly contributed to our knowledge of the composition of the universe.
		These lines can be used to identify the chemical elements in distant stars, but they also tell us the radial velocity.
		The line goes through the origin (0,0) because that represents our home position (zero distance) and we are not moving away from ourselves (zero speed).
	www.indiana.edu /~geol105/images/gaia_chapter_1/visible_light_spectral_emission_.htm (671 words)

	Stellar Classifications
		Some of these lines are Helium (in hotter stars), Hydrogen, ionized Calcium (K lines), and the 4226 Angstrom emission line of neutral Calcium in type O and B stars.
		In the cooler stars Titanium Oxide lines are indicative of class M stars, Zirconium Oxide lines are found in the emission lines of type S stars, and Carbon lines are used to classify types R and N stars.
		Hydrogen, helium, and iron emission lines vary from example to example, may be confused with the background (completely obliterated), and the rate of change of the variability changes.
	business.fortunecity.com /rowling/167/SuperNovae/Classifications.html (2289 words)

	EMSAO Parameters
		Following the number of lines found and the number of lines fit, the velocity, error, height, width, and equivalent width are then given for each line, with zero values indicating that the line was not used in the fit.
		Following the number of lines found and the number of lines fit, the velocity, error, height, width, equivalent width, and equivalent width error are then given for each line, with zero values indicating that the line was not used in the fit.
		Following the number of lines found and the number of lines fit, the wavelength shift and error in Angstroms, height, width in Angstroms, equivalent width, and equivalent width error are then given for each line, with zero values indicating that the line was not used in the fit.
	tdc-www.harvard.edu /iraf/rvsao/emsao/emsao.par.html (2272 words)

	Emission and Absorption Lines
		Absorption lines are based on the same physical principle as emission lines: they involve an atom jumping from one particular energy level to another.
		Emission and absorption lines can tell us a great deal about a distant celestial source, but they only occur under certain conditions.
		One of the strongest lines in the spectrum above is due to a transition in sodium atoms.
	spiff.rit.edu /classes/phys301/lectures/spec_lines/spec_lines.html (1775 words)

	Atomic Absorption and Emission Spectra (Site not responding. Last check: )
		The emission lines correspond to photons of discrete energies that are emitted when excited atomic states in the gas make transitions back to lower-lying levels.
		We may view a continuum spectrum as an emission spectrum in which the lines overlap with each other and can no longer be distinguished as individual emission lines.
		Emission or absorption processes in hydrogen give rise to series, which are sequences of lines corresponding to atomic transitions, each ending or beginning with the same atomic state in hydrogen.
	www.cartage.org.lb /en/themes/Sciences/Astronomy/Modenastronomy/Interactionoflight/AtomicAbsorption/AtomicAbsorption.htm (461 words)

	Spectra of Gas Discharges
		Below are images of the spectra of the lines of each element which would be observed as emission lines in an electrical gas discharge.
		All data are taken from the NIST Atomic Spectra Databaseby the National Institute of Standards and Technology, Gaithersburg, MD., U.S.A. The line intensities are as given in these tables, to give an impression of the relative line strength.
		However, it must be emphasized that the spectra shown may not correspond to the discharges we see in the form of various street lamps, because the excitation conditions (electric voltage, temperature, density) may well be different...
	astro.u-strasbg.fr /~koppen/discharge (342 words)

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