
	Where results make sense

Topic: Absorption lines

	Spectral line - Wikipedia, the free encyclopedia
		A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies.
		Absorption and emission lines are highly atom-specific, and can be used to easily identify the chemical composition of any medium capable of letting light pass through it (typically gas is used).
		Isomer shift is the displacement of an absorption line due to the absorbing nuclei having different s-electron densities from that of the emitting nuclei.
	en.wikipedia.org /wiki/Absorption_lines (1169 words)

	Absorption spectrum - Wikipedia, the free encyclopedia
		An absorption spectrum is, in a sense, the inverse of an emission spectrum.
		Every chemical element has absorption lines at several particular wavelengths corresponding to the differences between the energy levels of its atomic orbitals.
		Absorption spectra can therefore be used to identify elements present in a gas or liquid.
	en.wikipedia.org /wiki/Absorption_spectrum (408 words)

	ABSORPTION LINES IN STELLAR ATMOSPHERES (Site not responding. Last check: 2007-10-01)
		Absorption lines in stellar atomspheres occur whenever a cooler gas (e.g.
		Absorption occurs when an incoming photon has an energy that is equal to the energy level difference between some lower energy level and a higher energy level.
		This applet is designed to have the students measure the strength of the absorption lines as a function of temperature.
	jersey.uoregon.edu /absorption/abs122.html (361 words)

	Spectrum of Quasar 0237-233 - Absorption Lines
		Thus was born the multiple-red shift hypothesis for the absorption lines of quasars.
		BSBC state "The wavelengths of the lines are probably accurate to 0.3 Å except in the case of blended lines, where the error may be twice as large".
		The reported equivalent widths of lines by BSBC appear to indicate that in some cases, besides the proposed identifications, there is blending due to unknown components.
	laserstars.org /V1988/absorption.html (1599 words)

	absorption line concept from the Astronomy knowledge base (Site not responding. Last check: 2007-10-01)
		Like emission lines, absorption lines betray the chemical composition and velocity of the material that produces them.
		interstellar line (4 kinds, 18 facts) - Sharp, distinct absorption lines superposed on stellar spectra, produced by the interstellar gas located between the source and the observer.
		Strongest are the D lines, followed by the H and K lines, and the K I doublet at 7699 and 7644 Å.
	www.site.uottawa.ca:4321 /astronomy/absorptionline.html (265 words)

	Emission and absorption 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.
		Using this observation it was then predicted that a new element existed whose absorption lines corresponded to the ones observed in sunlight.
		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)

	4.1 Analyzing H I Lyman-alpha lines
		The centers of the stellar emission lines are obliterated by broad, saturated H I absorption.
		Cen B. The upper solid line is the assumed stellar emission profile and the dashed line is the ISM absorption alone.
		Cen line of sight, which is roughly in the upwind direction relative to the LISM flow seen by the Sun, the heliospheric absorption is redshifted primarily because of the deceleration and deflection of interstellar material as it crosses the bow shock.
	solarphysics.livingreviews.org /Articles/lrsp-2004-2/articlesu4.html (1797 words)

	quasar absorption lines
		Besides discussing (i) absorption troughs and (ii) absorption lines from clusters, we also consider (iii) photon scattering by free electrons in the intervening medium and (iv) spreading of a radio beam due to inhomogeneities in the ionized gas that is traversed.
		The article reviews the state of quasar absorption line research circa 1980, including a prediction of the absorption lines that are most likely to be observed with HST and two tests for the origins of the absorption systems.
		It is shown that the absence of OI and NI absorption lines in the observed optical absorption spectra of quasi-stellar radio sources indicates that 21-cm absorption lines wider than 100 kHz are likely to be weak unless the heavy-element abundance in the absorbing material is low.
	www.sns.ias.edu /~jnb/Papers/Preprints/earlypapers.html (1453 words)

	High-order Balmer series and HeI absorption-lines
		The reason is that the optical spectra of hot stars are dominated by absorption lines of H and He, with only very weak metallic lines (Walborn and Fitzpatrick 1990).
		This indicates that the Balmer absorption lines in IC 3639 are narrower than in NGC 205, and the population responsible for the H absorption features is probably dominated more by B stars than by A stars.
		We have measured the width of H63#63 in the stars from the atlas of Jacobi, Hunter, and Christian (1984), and the FWHM of a A2V star is 23 Å and B0V star is 11 Å.
	www.iaa.es /~rosa/research/Seyferts/s2/node23.html (1192 words)

	QSO Absorption Lines and Other Cosmological Probes
		Lines of sight toward various distant QSOs often intersect clouds of cold interstellar gas.
		They are responsible for the copious amounts of Lyman-alpha absorption lines seen in the direction of most distant QSOs.
		This is known as the Lyman alpha forest as there are literally a forest of absorption lines that come from clouds located at different redshifts along the line of sight.
	zebu.uoregon.edu /1997/ph410/l22.html (1555 words)

	Spectra
		Hydrogen emission lines are radiated by a hot, thin hydrogen gas, and appear at the same wavelengths as the hydrogen absorption lines.
		The absorption lines in the Sun and stars can be identified with individual chemical elements or molecular compounds by comparing their positions in the spectrum (their wavelengths) with those observed from pure sources in the laboratory.
		The "strength" of an absorption line -- the amount of energy removed from the spectrum -- depends on the amount of the particular chemical element in the star causing the line and on the efficiency of absorption.
	www.astro.uiuc.edu /~kaler/sow/spectra.html (5857 words)

	Stanford SOLAR Center -- Ask A Solar Physicist FAQs - Answer
		The cores of the Sodium D resonance lines are formed above the overshoot region and have a blue shift of around 0.005km/s (it being non-zero due to the Doppler shifted contributions to the line-wings that are formed lower down in the photosphere).
		It should be noted that, since the resulting line profiles are asymmetic, the actual size of the wavelength shift of any photospheric line depends on the part of the profile used in its determination; the above values refer to the wavelength derived from the bottom 20% of the line profile (i.e.
		As one moves away from the centre of the solar disk the line of sight through the solar atmosphere ceases to be vertical and samples the horizontal motions in the granular flow in addition to the vertical ones.
	solar-center.stanford.edu /FAQ/Qabsorption.html (634 words)

	Identifying Lines in the Solar Spectrum (Site not responding. Last check: 2007-10-01)
		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.
		Now we know that each absorption line is caused by a transition of an electron between energy levels in an atom.
		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.
	astro.washington.edu /labs/clearinghouse/labs/Solarspec/sunspec.html (527 words)

	absorption lines - @forums
		I know nothing about science and I know absorption lines is something scientific but I personally interpreted it as my defences are down and I feel weak and open.
		Absorption lines, for me, is like defence lines, which have been used till they broke.
		Now, absorbtion lines being frayed, i feel kind of like that is saying that her distinctive lines are not intact, that she isn't as able to control the fluids going in and out, metaphorically speaking.
	www.atforumz.com /showthread.php?t=52966 (858 words)

	quasar absorption lines
		Abstract: We present a catalogue of absorption lines obtained from the analysis of the ultra-violet spectra of 66 quasars.
		This is the third of a series of catalogues of absorption lines produced from the survey and increases the number of quasars whose higher resolution (R = 1300) spectra we have published from 17 to 83.
		New higher resolution measurements of the absorption lines in the UV spectra of 11 quasars with emission-line redshifts that lie between 0.3 and 1.0 are reported.
	www.sns.ias.edu /~jnb/Papers/Preprints/keyproject.html (758 words)

	Energy levels, wavelengths, transition probabilities
		Atomic data for permitted resonance lines of atoms and ions from H to Si, and S, Ar, Ca and Fe.
		Ionization thresholds and strongest lines of atoms and ions.
		Observed lines and lines in the CHIANTI database between 50 and 1100 A Dere et al.
	www.pa.uky.edu /~verner/lines.html (557 words)

	Atomic Absorption and Emission Spectra
		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.
		An absorption spectrum occurs when light passes through a cold, dilute gas and atoms in the gas absorb at characteristic frequencies; since the re-emitted light is unlikely to be emitted in the same direction as the absorbed photon, this gives rise to dark lines (absence of light) in the spectrum.
		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)

	CSA - Fact Sheet 5: Absorption Lines in The Solar Spectrum
		In Fraunhofer's time it was not realized that the spectral lines were related to specific atomic elements so they were simply catalogued according to their strength, the darkest was designated with the letter A then B followed by C an so on.
		The Fraunhofer lines seen in the solar spectrum are a combination of the lines produced as sunlight passes through the outer layers of the Sun's atmosphere plus the lines produced as the sunlight passes through the Earth's atmosphere.
		By comparing the spectra of sunlight before and after it has passed through the Earth's atmosphere it is possible to "tease out" which lines arise from atoms and molecules in that part of the Earth's atmosphere through which the sunlight has travelled.
	www.space.gc.ca /asc/eng/educators/resources/scisat/grade9-factsheet5.asp (350 words)

	Observations of the 2142-4420 Cluster
		Note that in QSO 2138-4427, strong absorption lines were invariably detected at the expected wavelengths, while in QSO 2139-4434 the lines were weaker and at slightly shifted wavelengths.
		We conclude that the central absorption component in QSO 2138-4427 does contain metals, roughly as measured, while for QSO 2139-4434 some or all of the putative lines (except C IV) may be misidentified Ly forest lines.
		In QSO 2138-4427 the Ly line shows broad wings, and strong absorption is seen at the expected wavelength of most common metal absorption lines: it therefore seems probable that this is, as modelled, a high column density absorption system, probably lying on the column density borderline between Lyman-limit and damped Ly systems.
	www.atnf.csiro.au /pasa/18_1/francis/paper/node2.html (1710 words)

	Fraunhofer Absorption Lines (Text) (Site not responding. Last check: 2007-10-01)
		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 (195 words)

	Spectral Classification of Stars
		The behavior of absorption lines and the continuum radiation is also examined.
		Absorption lines cause dark features in the continuum emission where the radiation is removed.
		Absorption lines occur when an electron absorbs energy from the spectrum to move up the energy levels in the atom.
	www.astro.washington.edu /labs/clearinghouse/labs/Spectclass/spectralclassweb.html (771 words)

	ABSORPTION LINES IN STELLAR ATMOSPHERES (Site not responding. Last check: 2007-10-01)
		This one in which the instructions are given and a smaller one which contains the actual applet that we will be using.
		Ask them to record the wavelengths and intensities of the dark lines they will eventually see on the spectrum.
		This can be down by rolling the cursor over the dark line.
	jersey.uoregon.edu /tmp/absorption_ins.html (463 words)

	IMSA Astrophysics: Distance Ladder
		Other absorption lines, such as those produced by He and Ca, can also be determined in the same way.
		However, the pattern of absorption lines have long been known to be shifted for some stars and galaxies.
		This shift is due to the Doppler effect, where light waves produced by a source moving toward the observer are compressed, producing a shift toward the blue end of the visible light spectrum, and light waves produced by a source moving away produce a shift toward the red.
	staff.imsa.edu /science/astro/astrometry/hubble.html (912 words)

	Astronomy 122 - Spectroscopy
		The modern view of the hydrogen atom thinks of the electron as a "cloud" surrounding the proton in the nucleus, but only certain clouds are possible, so the orbital energies are still quantized.
		Photons (the quantum of electromagnetic radiation) can be absorbed or emitted by an atom, boosting the electron to an excited state (on absorption) or bring the electron to a lower energy state (on emission).
		Line broadening is caused by the environment in which the emission or absorption occurs
	physics.uoregon.edu /~jimbrau/astr122/Notes/Chapter4.html (721 words)

	Newsletter issue 11 (Site not responding. Last check: 2007-10-01)
		Such common absorption lines are plausibly produced by gas clouds associated with galaxies that constitute a cluster (group) of galaxies at z=2.24
		A pair of dashed, dash-dotted, and dotted lines in Figure 2 indicate the 1-sigma, 2-sigma and 3-sigma distributions of artificial galaxies, respectively.
		If they are attributed to H-alpha emission lines on the band-pass of the 2.122(S1), we can estimate the lower limits of their star formation rates to be >125, and >54 Mo per year for obj1 and obj2, respectively.
	www.jach.hawaii.edu /UKIRT/publications/Newsletter/issue11/research.html?printable=1 (2693 words)

	Spectral Lines in Stars - Absorbtion and Emission
		Photons with 10.2 eV of energy are absorbed, leaving an absorption line.
		Therefore, if you do not see hydrogen lines in the hot cloud's spectrum, you can conclude it is hotter than 10,000 K. However, if the cloud were too cool, then the light would not have enough energy to boost its electrons into higher energy levels.
		For most elements, there is a certain temperature at which their emission and absorption lines are strongest.
	skyserver.sdss.org /dr1/en/proj/advanced/spectraltypes/lines.asp (597 words)

	ESA Science & Technology: IAU Colloquium No. 199: Probing Galaxies Through QSO Absorption Lines (Site not responding. Last check: 2007-10-01)
		QSO absorption line spectroscopy is an essential research tool for understanding the Universe over a large range of redshifts.
		The only previous large meeting devoted to quasar absorption lines was held in 1997 in France at the Institut d'Astrophysique de Paris.
		Absorption line studies are playing an ever more important role in our understanding of galaxy formation an evolution.
	sci.esa.int /science-e/www/object/index.cfm?fobjectid=36324 (183 words)

	Common Absorption Lines In Two Quasars
		(1967) (33 absorption lines), Burbidge (1967) (20 lines), Greenstein and Schmidt (1967) (40 lines), Bahcall, Greenstein and Sargent (1968) (49 lines) and by Burbidge et al.
		The coincidences between the wavelength of lines in 1122-1648 and 0237-233 is occurring because the shells of these two stars are quite similar.
		Common lines in the spectra of quasar 01122-1648 and 0237-233.
	laserstars.org /2005c (1055 words)

	Chapter 23: The Stars and Their Spectra
		The absorption lines and the continuum are both formed in the photosphere; the fact that absorption lines are detected shows that the outer part of the photosphere is cooler than the inner part of the photosphere.
		The absorption lines are formed in cool clouds of gas outside the Sun and stars.
		The absorption lines are formed in the upper photosphere as continuum from the lower photosphere passes through it.
	www.williams.edu /astronomy/ETU6/ETU5/chapter23_5th.html (1361 words)

Try your search on: Qwika (all wikis)