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Topic: Lyman alpha line

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	Lyman (Site not responding. Last check: 2007-11-04)
		Lyman, Mississippi Lyman is a town located in 2000 census, the town had a total population of 1,081.
		Lyman, Nebraska Lyman is a village located in 2000 census, the village had a total population of 421.
		Lyman-alpha line The Lyman-alpha line is a wavelength is approximately 121.6 nm.
	www.brainyencyclopedia.com /topics/lyman.html (453 words)

	Alpha (Site not responding. Last check: 2007-11-04)
		Alpha 1-antitrypsin deficiency Alpha 1-antitrypsin deficiency (A1AD) is a liver disease.
		Alpha, Illinois Alpha is a village located in 2000 census, the village had a total population of 726.
		Alpha and Omega ministries Alpha and Omega ministries is the Christian apologetics and theology ministry of James White....
	www.brainyencyclopedia.com /topics/alpha.html (1276 words)

	Active Galaxies and Quasars - the Lyman-alpha Forest (Site not responding. Last check: 2007-11-04)
		These are Lyman alpha absorption from foreground structures, in which the quasar light probes an otherwise invisible component of cosmic gas.
		The strong and broad emission peak is Lyman alpha, which is almost chopped in half by the onset of the Lyman alpha forest in the high-redshift quasar.
		Hundreds of lines can be identified in the spectrum of 1422+2309, with the densest concentration near the quasar redshift - this is a very general feature showing how the density of Lyman alpha absorbers decreases with cosmic time.
	www.astr.ua.edu /keel/agn/forest.html (431 words)

	Astronomers measure winds from solar-like stars
		The presence of a stellar wind is indicated by a subtle absorption signature in the Lyman-alpha line.
		Alpha Centauri itself is a binary star 4.39 light years from the sun consisting of a near twin of the sun and a somewhat cooler star.
		Toward Alpha Centauri additional absorption is in fact observed, which indicates that the strength of the wind from each of the two stars in the binary system is about the same as that of the sun.
	www.udel.edu /PR/UpDate/01/9/Astronomers.html (1239 words)

	Damped Lyman Alpha Systems (Site not responding. Last check: 2007-11-04)
		The Lyman alpha (Lya) forest is an absorption phenomenon in the spectra of back-ground quasistellar objects (QSOs).
		This prediction was soon followed by the first observation of numerous dicrete absorption lines blueward of the lyman alpha emission line in QSO spectra It can be observed in the ultraviolet (UV) and optical wavelength range, from the local universe up to the highest redshifts where QSOs are found (currently z ~ 5).
		A small fraction of the lines in the forest are not caused by HI but belong to the UV transitions from several common metals or heavy metal ions (various ionization stages of C, O, Mg,Si, Fe,and Al are most frequently seen).
	www.macalester.edu /astronomy/research/fitih/dla.html (309 words)

	Lyman-alpha forest - Wikipedia, the free encyclopedia
		In astronomical spectroscopy, the Lyman alpha forest is the sum of absorption lines seen in spectra of distant galaxies and quasars, beginning from the Lyman alpha line at 121.6 nm to shorter wavelengths (higher photon energies).
		The forest is created by the fact that photons that come to us from distant light sources show Hubble redshift that is roughly proportional to the distance between us and the source of light.
		Since neutral hydrogen clouds at different positions between Earth and the distant light source see the photons at different wavelengths (due to the redshift), each individual cloud leaves its fingerprint as an absorption line at a different position in the spectrum as observed on Earth.
	en.wikipedia.org /wiki/Lyman-alpha_forest (241 words)

	The Large Area Lyman Alpha (LALA) Survey (Site not responding. Last check: 2007-11-04)
		Lyman alpha line emission is an efficient tool for identifying young galaxies at high redshift, because it is strong in systems with young stars and little or no dust-- properties expected in galaxies undergoing their first burst of star-formation.
		The Large Area Lyman Alpha survey is a project to obtain and study a statistically useful sample of these galaxies at high redshifts (so far, 350 candidates at z=4.5, 18 at z=5.7, and one confirmed at z=6.535).
		line to continuum ratio (equivalent width) that is highly suggestive of star formation in primitive conditions, since it can be explained by extremely low metallicity or by star formation skewed to the most massive stars, but not by ``normal'' stellar populations.
	icarus.stsci.edu /~rhoads/LALA/lala_home.html (768 words)

	Lyman alpha systems and cosmology (Site not responding. Last check: 2007-11-04)
		The Lyman series is the series of energies required to excite an electron in hydrogen from its lowest energy state to a higher energy state.
		In Lyman alpha systems, the hydrogen is found in clouds in space, and the source for the photons are quasars (also called qsos), very high energy light sources, shining at us from behind these clouds.
		The Lyman alpha systems have deuterium in them too, and as these systems also have low amounts of metals (heavier elements), one might hope that they are measuring unprocessed or primordial deuterium.
	cfa-www.harvard.edu /~jcohn/lya.html (1508 words)

	Surveys for High Redshift Quasars (Site not responding. Last check: 2007-11-04)
		At the distance of PC 1247+3406, the Lyman alpha line is shifted to nearly 7200 Angstroms, which is at the far red end of the human eye's sensitivity.
		The continuum on the blue side of the Lyman alpha emission line is greatly suppressed relative to the continuum redward of the line, and the character of the continuum is also different (relatively smooth on the red side, very "choppy" on the blue).
		The intrinsic quasar continuum is smooth across the Lyman alpha emission line, but the large number of hydrogen clouds along the line-of-sight absorb most of the light (the sharp features blueward of the Lyman alpha emission line are due to individual hydrogen clouds at different redshifts).
	www.astro.psu.edu /users/dps/surveys.html (933 words)

	UVES investigates the environment of a very remote galaxy
		In practice, the Lyman-alpha absorption lines from the intervening clouds are located on the blueward side (i.e., at shorter wavelengths because of their smaller redshifts) of the main emission peak, giving rise to the concept of a "Lyman-alpha forest" of spectral absorption lines.
		At the indicated redshift, the Lyman-alpha line of atomic hydrogen (rest wavelength 121.6 nm) is observed at 452.8 nm, i.e.
		The Lyman-alpha absorption lines from intergalactic clouds along the line-of-sight (and at lower redshifts) are observed at shorter wavelengths.
	www.govertschilling.nl /nieuws/archief/2002/0203/020311_eso.htm (1854 words)

	Abstract (Site not responding. Last check: 2007-11-04)
		The present work aims at the modelling of three-dimensional radiation fields in gas clouds from the early universe, in particular as to the influence of varying distributions of density and velocity.
		Thus, the investigation of the Lyman-alpha line is of paramount importance for the theory of galaxy formation and evolution.
		The observed Lyman-alpha line -- or rather, to be precise, its profile -- reveals both the complexity of the spatial distribution and of the kinematics of the interstellar gas, and also the nature of the photon source.
	www.iwr.uni-heidelberg.de /sfb359/ATA/Abstract2002-36.html (262 words)

	AAS Press Release 2001-Jan-08
		Comparison of the Lyman alpha line spectrum of Alpha Centauri B (green histogram), the cooler star in the binary system, and Proxima Centauri (red histogram).
		The inferred interstellar absorption by hydrogen and deuterium is shown as a green dashed line.
		The Alpha Centauri and Proxima Centauri data agree very well on the red side of the hydrogen absorption produced in the region where the solar wind and interstellar gas collide, but on the blue side the Proxima Centauri data do not show the excess Lyman alpha absorption seen toward Alpha Centauri.
	www.dartmouth.edu /~hrm/R/AAS197press.html (1263 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)

	Electron Collision Shift of the Lyman-Alpha Line in H and He+ - Storming Media
		Abstract: The interaction of plasma microfields with radiating atoms and ions causes a line broadening that governs both the half-width and shift of the spectral line, i.e., the intensity distribution in frequency is altered to reflect the presence of the plasma.
		The line shifts are of particular interest both for their intrinsic value in terms of providing insight into the fundamental nature of the underlying physical processes affecting the emission of radiation as well as its diagnostic value in the study of high density plasmas.
		The formalism is applied to the Lyman-alpha line of hydrogen and ionized helium to determine the influence of various assumptions on the line shift as well as identifying the differences between a neutral and ionized radiator.
	www.stormingmedia.us /69/6920/A692002.html (290 words)

	altvw116
		The ultraviolet light accompanying an electron jump from the n=2 to the n=1 orbit is called “Lyman Alpha” radiation, because it is the longest wavelength member of a series of photons (or spectroscopic “lines”) corresponding to jumps ending in the n=1 orbit.
		Lyman had to do his work using a vacuum chamber, because all of the light in the Lyman series is in the far-ultraviolet region and is strongly absorbed by air.
		Therefore, the absorption line for deuterium is slightly shifted from that of hydrogen in the Lyman Alpha Forest.
	www.npl.washington.edu /AV/altvw116.html (1992 words)

	The Golden Age of Cosmology (Site not responding. Last check: 2007-11-04)
		At a resolution of about 5400, the spectra shows what appears to be the Lyman Alpha emission line redshifted from its rest UV (1216 Angstrom) wavelength to an observed wavelength in the IR of about 1.33745 microns.
		the Lyman alpha emission line is shifted from the ultraviolet into the red region of the electromagnetic spectrum.
		Because the recessional velocities are a significant fraction of the speed of light, the relativistic Doppler equation is used to estimate the redshift of a quasar.
	www.markelowitz.com /cosmology.htm (1086 words)

	UVCS PAPERS - Pre '93
		The intensity and profile of the Lyman alpha spectral line expected from the extended coronal plasma evolving during a coronal transient, when observed in the plane of the sky in the range of heliocentric distance 1.5 to 4 solar radii, are calculated.
		The dependence of the Lyman alpha line on the physical parameters of the examined structure is discussed.
		The effect of the integration along the line of sight on the spectral line profiles of the resonantly scattered Lyman alpha radiation emitted by low-density coronal holes at heights above 1.5 R_s from Sun center is investigated.
	cfa-www.harvard.edu /uvcs/biblio/pre93.html (1189 words)

	[No title]
		We expect the D Lyman alpha line to be ~0.04 Angstrom large which gives a peak level of 3.83e-13 ergs/cm2-sec-Angstrom.
		As the D Lyman alpha line is thin, the observation of a dark limb is not crucial (as far as the emission angle is > 80 deg.).
		Hopefully, the H Lyman alpha emission should be weaker near the terminator.
	ecf.hq.eso.org /poa/FOS/props/4476c.pro (2998 words)

	Damped Lyman Alpha Systems (Site not responding. Last check: 2007-11-04)
		Using various line diagnostics, Prochaska and Wolfe (1997,1998) concluded that the absorption signature of metal lines were indicative of massive, cold, rotating disks with circular velocities often in excess of ~ 200 km/s.
		Their mapping showed that velocity of lines is approximately equal to that of the HI rotational velocities, suggesting that DLAs can be associated with rotating disk galaxies.
		Hence, what this line of evidence indicates is that these systems could be represented as progenitors of both kind of galaxies.
	www.macalester.edu /astronomy/research/fitih/kine.html (259 words)

	CFHT and VLT Identify Extremely Remote Galaxy (ESO Press Release 12/03)
		The longer the wavelength of the observed Lyman-alpha line, the larger is the redshift and the distance, and the earlier is the epoch at which we see the galaxy and the closer we come towards the moment that marked the end of the "Dark Ages".
		Together with the observed asymmetry of the line, this is a clear spectral fingerprint of the redshifted Lyman-alpha emission line from a distant galaxy.
		For a redshift of 6.17, the Lyman-alpha line of atomic hydrogen (rest wavelength 121.6 nm) is observed at wavelength 871.9 nm, i.e.
	www.eso.org /outreach/press-rel/pr-2003/pr-12-03.html (2816 words)

	[No title] (Site not responding. Last check: 2007-11-04)
		These emission lines are very distintinctive in the cube that simulates the spectrum of a young star forming clump.
		Prominent emission lines of known wavelengths are ideal for establishing the redshift, while features such as the hydrogen recombination lines can be used to estimate the star formation rate.
		The strength of the Lyman alpha line is very uncertain because it is strongly absorbed by interstellar dust.
	astron.berkeley.edu /~jrg/ngst/star-forming-galaxies.html (230 words)

	Gemini Observatory
		The galaxy was first identified in the Large Area Lyman Alpha (“LALA”) survey, a deep imaging survey conducted at the Kitt Peak National Observatory using the CCD Mosaic-1 camera at the 4-meter Mayall Telescope (Figure 1).
		The properties of this line can be used to study the reionization process because neutral intergalactic hydrogen should scatter Lyman alpha light, hiding it from view in much the same way that a morning fog can obscure the Sun.
		For example, if the line is Doppler-shifted to longer wavelengths before it reaches the intergalactic gas (either by a drift velocity of the emitting galaxy or by interaction with gas internal to that galaxy), the intergalactic scattering can be reduced.
	www.gemini.edu /index.php?option=content&task=view&id=28 (1072 words)

	Redshift 3.04 < z < 5.64 Lyman alpha emitters preprint
		High redshift galaxies showing strong Hydrogen Lyman alpha emission may be extremely faint, or undetected, in deep optical or IR continuum images - even in deep exposures made with the 10 m Keck Telescope or with the Hubble Space Telescope.
		The Lyman alpha emitting galaxies are currently missing from our census, but are significant contributors to the net star formation at high redshift.
		The objects detected here were found in a survey with the Keck II Telescope that uses both these techniques to find these line emitting galaxies, in order to learn about their number density, physical properties, star formation rates, and their relationship to brighter high-redshift galaxies.
	www.ifa.hawaii.edu /faculty/hu/emitters.html (581 words)

	Lyman Alpha Forest (Site not responding. Last check: 2007-11-04)
		As a result the absorption lines are all on the blue or shorter wavelength side of the quasar emission line.
		So if Arp were correct the Lyman alpha forest would have to be an intrinsic property of the quasar, which would be a very unlikely situation.
		For Arp to be correct the intrinsic absorption lines would have to act exactly like the intervening clouds would act under the standard hypothesis that the quasar redshift is entirely cosmological.
	www.astro.ucla.edu /%7Ewright/Lyman-alpha-forest.html (390 words)

	pr-07-02.html
		The 20 galaxies that have been confirmed to be emitting the sharp colours due to glowing hydrogen gas at the distance of the radio galaxy are encircled in blue.
		To search for galaxies at the same distance as the radio galaxy, the pictures were optimised in sensitivity for the sharp colour emitted by glowing hydrogen gas at the distance of the radio galaxy [2].
		At the indicated redshift, the Lyman-alpha line of atomic hydrogen (rest wavelength 121.6 nm) is observed at 620 nm, i.e.
	www.eso.org /outreach/press-rel/pr-2002/pr-07-02.html (1575 words)

	Bad Astronomy Bulletin Board :: View topic - Redshifts are cosmological: the Lyman Alpha Forest and Arp (Site not responding. Last check: 2007-11-04)
		Redshifts are cosmological: the Lyman Alpha Forest and Arp
		When a spectrum is taken of a high-redshift quasar, it invariably shows a series of absorption lines blueward of the Lyman alpha line (this is the emission line of hydrogen where the electron drops from the 2nd to the 1st energy level, and has a wavelength of 1216 Angstroms).
		The cosmological interpretation of the Lyman alpha forest implies that the light is interacting with intervening material, mainly hydrogen.
	www.badastronomy.com /phpBB/viewtopic.php?t=3520&highlight= (3444 words)

	Red Shift (Site not responding. Last check: 2007-11-04)
		Galactic redshifts arise because of the apparent recession of the galaxies, caused by the expansion of the Universe.
		The Sun, for example, has a continuous spectrum that is roughly that of a 5,800 K flbody, and it has a complicated line spectrum that arises from the many different elements in its atmosphere.
		In particular, the strong Lyman alpha emission line, whose rest wavelength is 1215 Angstroms, can often be used to measure the galaxy's redshift.
	homepages.ihug.co.nz /~hardy/RedShift.html (449 words)

	Interstellar Medium
		Of particular importance are the LISM absorption lines seen within the so-called Lyman-alpha line, which is emitted by neutral hydrogen (H I) atoms in the observed stars.
		Superimposed on the very broad stellar emission line are a broad interstellar H I absorption feature and a much narrower deuterium (D I) absorption feature.
		In analyzing the Lyman-alpha lines of some nearby stars, we found that we could not explain the observed H I absorption by LISM absorption alone.
	casa.colorado.edu /~woodb/resint2/resint2.html (863 words)

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