Opacity of the solar core
Solar core opacity, investigating individual heavy elements influence and effect of changes in abundances
Watson, W. D.↗
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Atmospheric structure of cool stars with particle opacity
Cool star atmospheric structure, discussing models with and without graphite particle inclusion opacity
Krishna Swamy, K. S.↗
Shock tube technique for measuring opacities at high pressures for gaseous-core nuclear rockets
Potential high performance shock tube for high pressure opacity measurements of gaseous rocket propellants for nuclear rocket engines
Patch, R. W.↗
Status of opacity calculations for application to uranium fueled gas core reactors
Opacity calculations for application to uranium fueled gas-core reactors
Patch, R. W.↗
Uranium plasma opacity measurements
Absolute opacities of uranium plasma measured by using gas-driven shock tube
Koopman, D. W.↗
On the use of linear interpolation in opacity tables
Errors resulting from linear interpolation use in opacity tables for stellar interior calculations
Rood, R. T.↗
Metal line blanketing and opacity in the ultraviolet of alpha 2 Canum Venaticorum
Ultraviolet photometry by OAO-2 was made of alpha 2 CVn covering the entire 5.5d period of this magnetic Ap variable. The light curves ranging from 1330 A to 3320 A indicate the dominant role of rare-earth line-blanketing in redistributing flux. In a broad depression of the continuum covering 2300-2600 A, scanner observations possibly identify strong lines of Eu III as major contributors to this feature. At maximum intensity of the rare-earth lines, the ultraviolet continuum shortward of 2900 A is greatly diminished while the longer wavelength regions into the visual become brighter. In addition, there is evidence that the hydrogen line opacity is variable and the photoionization edge of Si I at 1680 A is identified.
Molnar, M. R.↗
Opacity probability distribution functions for electronic systems of CN and C2 molecules including their stellar isotopic forms.
The basis and techniques are presented for generating opacity probability distribution functions for the CN molecule (red and violet systems) and the C2 molecule (Swan, Phillips, Ballik-Ramsay systems), two of the more important diatomic molecules in the spectra of carbon stars, with a view to including these distribution functions in equilibrium model atmosphere calculations. Comparisons to the CO molecule are also shown. T he computation of the monochromatic absorption coefficient uses the most recent molecular data with revision of the oscillator strengths for some of the band systems. The total molecular stellar mass absorption coefficient is established through fifteen equations of molecular dissociation equilibrium to relate the distribution functions to each other on a per gram of stellar material basis.
Querci, F.↗
Simplified method for measuring mean opacities and effective absorption coefficients.
Use of wide bandwidths and a number of path lengths to obtain mean opacities and effective absorption coefficients. This method is applicable if the temperatures and pressures at which these qualities are desired can be duplicated experimentally. Additional restrictions are that the gas in the experiments must be essentially isothermal, homogeneous, nonscattering, and in local thermodynamic equilibrium. The method is most advantageous in shock tube experiments and experiments utilizing a pulsed arc of cylindrical symmetry viewed axially.
Patch, R. W.↗
Solar neutrinos and the influences of opacity, thermal instability, additional neutrino sources, and a central black hole on solar models
Significant quantities that affect the internal structure of the sun are examined for factors that reduce the temperature near the sun's center. The four factors discussed are: opacity, central black hole, thermal instability, and additional neutrino sources.
Stothers, R. B.↗
On the He-H2 thermal opacity in planetary atmospheres.
The pressure-induced absorption coefficient for He-H2 mixtures is poorly known for the range of physical conditions in the atmospheres of the major planets, largely because of the uncertainty in the overlap parameter of the induced dipole moment. We have reduced this uncertainty by examining the extent to which the published measurements and the existing theory specify this parameter. Furthermore, we show that this parameter should be quite accurately determined if laboratory measurements of this opacity are extended to frequencies below 300/cm.
Trafton, L.↗
Solar neutrinos and the influence of radiative opacities on solar models
Use of new radiative opacities based on the hot Thomas-Fermi model of the atom yields a predicted solar neutrino flux which is still considerably larger than the flux observed in Davis's Cl-37 experiment.
Carson, T. R.↗
A four-channel portable solar radiometer for measuring particulate and/or aerosol opacity and concentration of NO2 and SO2 in stack plumes
Solar absorption radiometry has been investigated as a method of measuring stackplume effluents. A simple and inexpensive instrument was constructed for observing the sun at four wavelengths: 800, 600, 400, and 310 nm. Higher wavelength channels measured the effect of the particulates and NO2, and an ultraviolet channel measured the contribution of SO2 to the attenuation. Stack-plume measurements of opacity and concentration of NO2 and SO2 were in basic agreement with in-stack measurements. The major limitation on the use of the radiometer is the requirement for an accessible viewing position which allows the sun-plume-observer relationship to be attained. It was concluded that the solar radiometer offers an inexpensive method for monitoring plume effluents when the viewing position is not restricted.
Exton, R. J.↗
A history of Mars atmospheric opacity in the southern hemisphere during the Viking extended mission
A history of developing opacity in the Mars southern hemisphere during the Viking extended mission has been compiled using orbiter images obtained at high altitude. Observations of changing contrasts under similar viewing conditions have been modeled by multiple-scattering intensity transfer equations that have produced a temporal description of changes in optical depth and particle-scattering properties within a network of control points. The results are presented in the form of Mercator and perspective plots for various dates.
Thorpe, T. E.↗
Atmospheric opacity in the Schumann-Runge bands and the aeronomic dissociation of water vapor
Knowledge of the aeronomic production of odd hydrogen in the dissociation of water vapor is limited by uncertainties in the penetration of solar irradiance in the Schumann-Runge bands of O2 and by incomplete information concerning the products of photolysis at Lyman alpha. Consideration of all error sources involved in computing the H2O dissociation rate in the wavelength region 175-200 nm leads to an estimated uncertainty of plus or minus 35% at an altitude of 90 km for an overhead sun. The uncertainty increases with decreasing altitude such that the true dissociation rate at 60 km for an overhead sun lies between 0.45 and 1.55 times the results computed using the best input parameters currently available. Calculations of the H2O dissociation rate by Lyman alpha should include the variation in O2 opacity across the solar line width. Neglect of this can lead to errors as large as 50% at altitudes where the process is the major source of odd hydrogen.
Frederick, J. E.↗
The C I opacity and physical structure of cool, very dense plasma in the solar corona
The physical structure of the cool material in the volume of the solar corona is investigated. The observational evidence is summarized in a table giving the brightness contrast in optical and EUV radiations. The state of ionization and the opacity sources are discussed, and a physical model is described that is consistent with the EUV and optical data. It is noted that a comparison of the EUV raster pictures with H-alpha and Ca K photoheliograms indicates that the material is commonly injected from below into relatively low-lying magnetic loops (fibrils) seen near sunspots and plages.
Foukal, P.↗
Sulfur dioxide and other cloud-related gases as the source of the microwave opacity of the middle atmosphere of Venus
Spacecraft radio occultation measurements imply the presence of a nonuniformly mixed gaseous absorber within, but mostly below, the main cloud layer of sulfuric acid-water droplets measured by Pioneer-Venus. Preliminary considerations of the amount, distribution, and effects of sulfur dioxide and other gases, which apparently are associated with and produce the cloud, indicate that they constitute an important, and probably the predominant, source of the observed microwave opacity of the middle atmosphere of Venus.
Steffes, P. G.↗
Mars atmospheric opacity effects observed in the Northern Hemisphere by Viking orbiter imaging
Viking orbiter television camera observations of Mars contrasts show variations of atmospheric opacity in the Southern Hemisphere. The study is extended into the Northern Hemisphere, over a longer time period, and results in a detailed description of photometric changes at the lander sites, as seen from orbit. During the period of January 1977 to April 1978, a series of four storms at 202 deg, 264 deg, 40 deg and 86 deg latitudes have provided photometric changes and planetwide aerosol distributions for 18 months. It is found that the large, forward-scattering particles did not enter the atmosphere at the storm's onsets. A reduction of atmospheric transmission by over 20% at visual wavelengths remained for nearly one Martian year.
Thorpe, T. E.↗