Carbon monoxide in the interstellar spectrum of zeta Ophiuchi
Equivalent widths of CO lines in interstellar absorption spectrum of zeta Ophiuchi
Smith, A. M.↗
SEARCH · Search NASA
Results for “Spectrum Width”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Theoretical line profiles in the ultraviolet spectra of early-type stars.
Theoretical line profiles in UV spectra of two early B stars from 911.6 to 3000 angstroms
STELLAR SPECTRUM↗
The 5520 A band of ammonia in the spectrum of Jupiter
Equivalent line widths of 5520 A ammonia band in Jupiter spectrum
Owen, T.↗
An optical region elemental abundance analysis of the chemically peculiar HgMn star chi Lupi
The optical spectrum of the chemically peculiar HgMn type binary star chi Lupi has been analyzed to determine atmospheric parameters and elemental abundances. Echelle spectra were obtained with the 3.9 m Anglo-Australian telescope to exploit the extreme shape-lined nature of the spectrum. This study was undertaken in support of ultraviolet analyses currently underway that utilize echell spectra obtained with the Hubble Space Telescope. For the B9.5 V primary star we obtain T(sub eff) = 10650 K, log g = 3.9, and xi = 0 km/s, while for the A2 V secondary, T(sub eff) = 9200 K, log g = 4.0, and xi = 2 km/s. Most of the elemental abundances are typical of HgMn stars with similar T(sub eff) showing an overall iron-peak elemental abundance distribution that is basically solar in nature with enhancement of the light elements Si, P, and S, as well as all detected elements heavier than the iron group. Abundances for several elements have been determined for the first time in this star, including several of the rare-earths. The secondary star spectrum shows Am star characteristics. We also discuss the relative merits of the equivalent width and synthetic spectrum techniques in determining the elemental abundences, concluding that the synthetic spectrum technique is necessary for obtaining abundances with the utmost accuracy.
Wahlgren, Glenn M.↗
Uncertainties of the Intensity of the 1130 nm Band of Water Vapor
Belmiloud, et al have recently suggested that the HITRAN line intensities in the 1130 nm water vapor band are much too weak. Giver, et at corrected unit conversion errors to make the HITRAN intensities compatible with the original measurements of Mandin, et al, but Belmiloud, et al believe that many of those line intensity measurements were too weak, and they propose the total intensity of the 1130 nm water vapor band is 38% stronger than the sum of the HITRAN line intensities in this region. We have made independent assessments of this proposal using 2 spectra obtained with the Ames 25 meter base path White cell. The first was made using the moderate resolution (8 nm) solar spectral flux radiometer (SSFR) flight instrument with a White cell absorbing path of 506 meters and 10 torr water vapor pressure. Modeling this spectrum using the HITRAN linelist gives a reasonable match, and the model is not compatible when the HITRAN line intensities are increased by 38%. The second spectrum was obtained with a White cell path of 1106 meters and 12 torr water vapor pressure, using a Bomem FTIR with near Doppler width resolution. This spectrum is useful for measuring intensities of isolated weak lines to compare with the measurements of Mandin, et al. Unfortunately, as Belmiloud et al point out, at these conditions the strong lines are much too saturated for good intensity measurements. Our measurements of the weak lines are in reasonable agreement with those of Mandin, et al. Neither of our spectra supports the proposal of Belmiloud et al for a general 38% increase of the absorption intensity in the 1130 nm water vapor band.
Giver, L. P.↗
Moessbauer effect measurement in single crystal iron subjected to cyclic stress
Backscattered Moessbauer spectra were recorded at different fatigue levels in cyclically fatigued high-purity single-crystal iron specimens in the form of rectangular strips with appropriate concentrators in the midplane. The Moessbauer spectra were submitted to a least-squares analysis to determine the isomer shift, quadrupole shift, hyperfine field, and peak spectral widths in each spectrum. It is shown that the quadrupole shift and the isomer shift changed little with fatigue, whereas the effective internal field and the associate line widths exhibit significant variation as a function of fatigue level. It is concluded that the impurity concentration builds up slowly with increasing fatigue level in the region of stress concentration. Since there is a direct correlation between crack initiation and defect concentration level, it is expected that Moessbauer measurements in the test specimen can provide a means of monitoring the impurity buildup presumed to be the eventual cause of fatigue crack initiation and failure.
Singh, J. J.↗
Variations in the UV spectrum of a Centauri
Equivalent width and central depth measurements of the ultraviolet absorption lines from the spectrum of the He I variable star a Cen HD 125823 are presented. The measurements are from 53 short wavelength, and 45 long wavelength, high resolution spectrographs taken with the IUE satellite over a 25 day period during July and August of 1978. Central depth measurements were of lines of Cr III, Mn III, V III, C III, Si II, and S II seen in the region between 1245 and 1255 A. Equivalent widths are of the three He I 2(3)s-n(3po) transitions found at 2945, 2829 and 2764 A. The period for cyclic intensity variations in He I is determined using a four parameter, least squares fit to a sinusoid. The IUE observations match both a period of 8.8163 + or - 0.0003 days and a previously unreported period of 9.2532 + or - 0.0003 days with equal minima for the least squares fit. The phase of Cr III maximum relative to He I maximum is found to be 0.53 cycles for the IUE observations.
Fahey, R. P.↗
Models of the hard X-ray spectrum of AM Herculis and implications for the accretion rate
Phenomenological fits to the hard X-ray spectrum of AM Hercules have failed to explain the high equivalent width (0.8 + or - 0.1 keV) of Fe K-alpha emission. The scattering and fluorescent line production in a cold or partially ionized accretion column of hard X-rays emitted at the base are investigated using the Monte Carlo method. It is shown that the Fe emission equivalent width observed in the spectrum of AM Her can be explained without resorting to an overabundance of Fe in the accreting material. For sufficient optical depth across the accretion column, equivalent widths of K-alpha emission even larger than the observed values can be obtained. The accretion rate and gravitational power can be deduced from the optical depth across the column, if the column size is known, and, together with the observed hard X-ray and polarized light luminosities, imply a lower limit for the luminosity in the UV to soft X-ray range, for which the observations give model-dependent values.
Swank, J. H.↗
Track Structure Model for Radial Distributions of Electron Spectra and Event Spectra from High-Energy Ions
An analytic method is described for evaluating the average radial electron spectrum and the radial and total frequency-event spectrum for high-energy ions. For high-energy ions, indirect events make important contributions to frequency-event spectra. The method used for evaluating indirect events is to fold the radial electron spectrum with measured frequency-event spectrum for photons or electrons. The contribution from direct events is treated using a spatially restricted linear energy transfer (LET). We find that high-energy heavy ions have a significantly reduced frequency-averaged final energy (yF) compared to LET, while relativistic protons have a significantly increased yF and dose-averaged lineal energy (yD) for typical site sizes used in tissue equivalent proportional counters. Such differences represent important factors in evaluating event spectra with laboratory beams, in space- flight, or in atmospheric radiation studies and in validation of radiation transport codes. The inadequacy of LET as descriptor because of deviations in values of physical quantities, such as track width, secondary electron spectrum, and yD for ions of identical LET is also discussed.
Cucinotta, F. A.↗
Optical emission from a fast shock wave - The remnants of Tycho's supernova and SN 1006
The faint optical filaments in Tycho's supernova remnant appear to be emission from a shock front moving at 5600 km/s. The intensity of the hydrogen lines, the absence of forbidden lines of heavy elements in the spectrum, and the width of the filaments are explained by a model in which a collisionless shock wave is moving into partially neutral gas. The presence of the neutral gas can be used to set an upper limit of approximately 5 x 10 to the 47th power ergs to the energy in ionizing radiation emitted by a Type I supernova. The patchy neutral gas is probably part of the warm neutral component of the interstellar medium. The existing information on the remnant of SN 1006 indicates that its emission is similar in nature to that from Tycho's remnant.
Chevalier, R. A.↗
A comparison of radar measurements of atmospheric turbulence intensities by both C sub n sup 2 and spectral width methods
There are two main techniques by which turbulence intensities in the atmosphere can be measured by radars. One is to utilize the absolute backscattered power received by the radar, and use this to deduce C sub n sup 2 (refractivity turbulence structure constant). With appropriate assumptions, this parameter can then be converted to an energy dissipation rate. The second method utilizes the width of the spectrum of the signal received by the radar. Neither of these techniques have been used a great deal, and they have never been properly compared. Thus it was not possible to determine the validity of the assumptions made in applying each technique, nor was it possible to determine the limitations of each method. The first comparisons of the two techniques are presented. Measurements were made with the Adelaide VHF ST radar, and the results of the comparison are discussed.
Hocking, W. K.↗
The hot DOA1 degenerate HZ 21 - A search for circumstellar/photospheric metals and peculiar absorption at He II
A high-resolution IUE spectrum of the hot DO1 degenerate HZ 21 was obtained by combining US1 + European 2 low-background observing shifts. The SWP image reveals a rich spectrum of interstellar absorption lines with an average velocity in the line of sight to HZ 21 of -30 km/s. However, there is no clear evidence of any highly or lowly ionized metal features which could be attributed to circumstellar, wind, or photospheric absorption. There is, however, a broad absorption trough at He II (1640) which was not unexpected, given the clear presence of He II (4686) absorption in this star's optical spectrum. The velocity width of He II (1640) appears consistent with photospheric absorption wings which appear to flank the geocoronal Ly-alpha emission feature. The He II (1640) feature reveals what appears to be a broad (310 km/s) emission reversal. Evidence is provided that the emission reversal is probably real.
Fritz, M. L.↗
Optical spectroscopy of IRAS sources with infrared emission bands. 1: IRAS 21282+5050 and the diffuse interstellar bands
Spectroscopy of the starlike optical counterpart to IRAS 21282+5050, a source with the hydrocarbon infrared emission band spectrum, shows an 07(f)-(WC11) planetary nebula nucleus suffering an extinction of 5.7 mag. Emission line widths in the WC spectrum are only approx. 100 km/s, indicating a very slow stellar wind. Optical diffuse interstellar bands (DIBs) are prominent. Five DIBs are strongly enhanced, namely lamda lamda 5797, 6196, 6203, 6283, and 6613. The presence of circumstellar hydrocarbon molecules may explain both the infrared emission bands and the enhanced DIBs.
Cohen, Martin↗
Optical spectroscopy of IRAS sources with infrared emission bands - IRAS 21282+5050 and the diffuse interstellar bands
Spectroscopy of the starlike optical counterpart to IRAS 21282+5050, a source with the 'hydrocarbon' IR emission band spectrum, shows an O7(f)-(WC 11) planetary nebula nucleus suffering an extinction of 5.7 mag. Emission-line widths in the WC spectrum are only about 100 km/s, indicating a very slow stellar wind. Optical diffuse interstellar bands (DIBs) are prominent, and five DIBs are strongly enhanced. The presence of circumstellar hydrocarbon molecules may explain both the IR emission bands and the enhanced DIBs.
Cohen, Martin↗
Self-Heterodyne Laser-Spectrum Analyzer
Apparatus measures spectral widths of light emitted by GaAs or other narrow-linewidth diode lasers at wavelengths between 800 and 900 nm. Operating on quasi-homodyne of self-heterodyne principle, apparatus provides relatively high spectral resolution: measures spectral widths of order of 100 kHz. Fine spectral resolution of apparatus provides data relevant to use of AlGaAs diode lasers in such applications as coherent optical communication through free space and injection seeding of solid-state lasers. Also used to explore connections between lifetimes and spectral widths of diode lasers.
Saif, Babak↗
Neutron production mechanism in a plasma focus.
The neutrons emitted by a plasma focus were analyzed by using a time-of-flight method. Flight paths as large as 80 m were used to obtain better than 10% energy resolution. The energy spectrum of neutrons from d-d reactions in the plasma focus shows a sharp onset with average maximum energies of 2.8 and 3.2 MeV in the radial and the axial directions, respectively. The average half-width of the energy spectrum was 270 keV with a shot-to-shot variation between 150 and 400 keV. Simultaneous measurements in the axial and radial directions showed no appreciable difference in the half-widths and thus indicated randomly oriented ion velocities in the plasma. A converging ion model is described which is found to be in agreement with the measured quantities.
Lee, J. H.↗
Spectrophotometry of Seyfert 2 galaxies and narrow-line radio galaxies
Results are reported for a spectrophotometric survey of several Seyfert 2 galaxies, intermediate Seyferts, and narrow-line radio galaxies. The emission-line spectra of the galaxies are analyzed, emphasizing line intensities, reddening, temperatures, densities, line strength correlations, line widths, and redshift differences. The continuous spectra are examined, and possible ionization sources are considered. It is found that: (1) there are no distinguishing differences between the spectra of Seyfert 2 galaxies and narrow-line radio galaxies; (2) the emission spectra are rich in lines from a wide range of ionization levels; (3) the continuum is starlight diluted by an underlying continuous spectrum; (4) the line widths of both classes of galaxies have the same distribution; (5) there appear to be regions of high and low ionization in the Seyfert 2 and narrow-line radio galaxies; (6) photoionization seems quite likely as the energy input to the gas; and (7) all the galaxies show a UV excess in their spectra.
Koski, A. T.↗
Causes of spurious features in spectral reflectance data
Several techniques are becoming common in the analysis of imaging spectrometer data that can lead to spurious absorption features or to changes in the position, width, and shape of actual absorption features. It is a common practice to calibrate AIS or other imaging spectrometer data by averaging each pixel along the flight line. The average is used to calibrate the spectral data by dividing the spectrum at each pixel by the average. If some pixels in the data set contain an absorption, then the average will also show an absorption. Some AIS data has had problems with wavelength stability from one scan line to the next which can produce spurious features with some analysis methods. If a pixel has a spectrum with an absorption having a different position or width than the spectrum used in a ratio, then the ratio can produce a spurious absorption at a different position and width than the true absorption feature. An average spectrum ratioed to each pixel will produce band shifts, and changes in width or shape. If continuum removal is performed by substraction rather than division, band positions can also be shifted.
Clark, Roger N.↗