192
192
May 6, 2010
05/10
by
Fischel, D
texts
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Influence of chemical composition on structure and metal index of stellar atmospheres
Topics: ABUNDANCE, CHEMICAL COMPOSITION, COMPOSITION (PROPERTY), STELLAR ATMOSPHERES, CHEMICAL COMPOSITION,...
415
415
Jul 6, 2010
07/10
by
WITKOWSKI, S
texts
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THE PRODUCTION OF PLASMAS BY LASER SPARK IS DISCUSSED ALONG WITH THE IRRADIATION OF SOLIDS FOR THE PRODUCTION OF HIGH TEMPERATURES FOR THERMONUCLEAR FUSION. EXPERIMENTAL STUDIES OF THE IRRADIATION OF SOLIDS INCLUDING SOLID DEUTERIUM, LIH, LID ARE REVIEWED, AND A UNIDIMENSIONAL PLANAR GAS-DYNAMICS MODEL WAS DEVELOPED TO STUDY THE PHASES OF PLASMA PRODUCTION. IT IS CONCLUDED THAT THE USE OF LASERS FOR INITIATING HYDROGEN BOMBS WILL NOT BE ACHIEVED IN THE FORESEEABLE FUTURE.
Topics: ATMOSPHERIC MODELS, SHOCK WAVES, STELLAR ATMOSPHERES, WAVE PROPAGATION, FINITE DIFFERENCE THEORY,...
189
189
May 23, 2011
05/11
by
Lagerloef, Gary S.E
texts
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Climatic dynamic topography variations in the Alaska gyre during the period 1968-1990 are described with an objective analysis of more than 12000 STD and XBT stations, and COADS wind stress data Interannual the dynamic height and SST variations were correlated and were consistent with recently described large-scale climatic shifts in the North Pacific. The gyre was centered more to the east, circulation appeared stronger, and SST was lower during the early to mid-1970s than during the 1980s....
Topics: STELLAR ATMOSPHERES, ABUNDANCE, ATMOSPHERIC MODELS, ERRORS, FAILURE, SPECTROSCOPY, POPULATIONS,...
Aims: We present a unique multi-epoch infrared interferometric study of the oxygen-rich Mira variable RR Aql in comparison to radiative transfer models of the dust shell. We investigate flux and visibility spectra at 8-13 microns with the aim of better understanding the pulsation mechanism and its connection to the dust condensation sequence and mass-loss process. Methods: We obtained 13 epochs of mid-infrared interferometry with the MIDI instrument at the VLTI between April 2004 and July 2007,...
Topics: DTIC Archive, NAVAL OBSERVATORY WASHINGTON DC, *INTERFEROMETRY, *STARS, DUST, RADIATIVE TRANSFER,...
We present a hot white dwarf (WD) luminosity function (LF) using data taken from the Sloan Digital Sky Survey (SDSS) Data Release 4. We present and discuss a combined LF, along with separate DA and non-DA as LFs. We explore the completeness of our LFs and interpret a sudden drop in the non-DA LF near 2 Mbol as a transition of the non-DA WD atmosphere into the DA one during WD evolution. Our LF should now be useful for estimates of recent star formation and for studies of neutrino and other...
Topics: DTIC Archive, NAVAL OBSERVATORY FLAGSTAFF AZ, *LUMINOSITY, *SURVEYS, *DIGITAL SYSTEMS, ATMOSPHERE...
289
289
Jun 19, 2010
06/10
by
Sobolev, V. V
texts
eye 289
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Stellar and planetary atmosphere light scattering theory based on probability
Topics: LIGHT SCATTERING, PLANETARY ATMOSPHERES, PROBABILITY THEORY, STELLAR ATMOSPHERES, LIGHT SCATTERING,...
742
742
Jul 11, 2010
07/10
by
JUCHEM, P
texts
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A GREAT DEAL HAS BEEN WRITTEN ABOUT THE PROJECT TO EXPLOIT WIND ENERGY TO PRODUCE ELECTRICAL ENERGY. THE CONTROVERSY OVER THE TREMENDOUS WIND WHEELS HAS NOT DIED DOWN, AND, IN THE AGE OF AN EVERGROWING DEMAND FOR ENERGY, IT HAS AGAIN BECOME A SUBJECT OF DISCUSSION. THE FOLLOWING IS A CONTRIBUTION TO THIS SUBJECT AND REFLECTS THE PERSONAL OPINION OF THE AUTHOR ABOUT THE PROJECT.
Topics: BINARY STARS, SIGNAL REFLECTION, STELLAR ATMOSPHERES, X RAY SOURCES, COMPTON EFFECT, CYGNUS...
We present optical spectroscopy and near-infrared photometry of 126 cool white dwarfs (WDs) in the Sloan Digital Sky Survey (SDSS). Our sample includes high proper motion targets selected using the SDSS and USNO-B astrometry and a dozen previously known ultracool WD candidates. Our optical spectroscopic observations demonstrate that a clean selection of large samples of cool WDs in the SDSS (and the SkyMapper, Pan-STARRS, and the Large Synoptic Survey Telescope data sets) is possible using a...
Topics: DTIC Archive, NAVAL OBSERVATORY FLAGSTAFF AZ, *PHOTOMETRY, *DWARF STARS, *SPECTROSCOPY, STELLAR...
467
467
Jul 26, 2010
07/10
by
Shih, T. I.-P.; Bailey, R. T.; Nguyen, H. L.; Roelke, R. J
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An efficient computer program, called GRID2D/3D was developed to generate single and composite grid systems within geometrically complex two- and three-dimensional (2- and 3-D) spatial domains that can deform with time. GRID2D/3D generates single grid systems by using algebraic grid generation methods based on transfinite interpolation in which the distribution of grid points within the spatial domain is controlled by stretching functions. All single grid systems generated by GRID2D/3D can have...
Topics: ATMOSPHERIC MODELS, BLACK BODY RADIATION, MATHEMATICAL MODELS, NOVAE, STELLAR ATMOSPHERES,...
885
885
Jun 12, 2011
06/11
by
NON
texts
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The mission of the Journal of Air Transportation (JA is to provide the global community immediate key resource information in all areas of air transportation. The goal of the Journal is to be recognized as the preeminent scholarly journal in the aeronautical aspects of transportation. As an international and interdisciplinary journal, the JAT will provide a forum for peer-reviewed articles in all areas of aviation and space transportation research, policy, theory, case study, practice, and...
Topics: STELLAR PHYSICS, PHOTOSPHERE, STELLAR ATMOSPHERES, X RAY ASTRONOMY, STELLAR WINDS, STELLAR SPECTRA,...
This document is a collection of five abstracts from papers written on the 'FUSE Observations of Galactic and LMC Novae in Outburst'. The titles are the following: (1) Analyzing FUSE Observations of Galactic and LMC Novae; (2) Detailed NLTE Model Atmospheres for Novae during Outburst: Modeling Optical and Ultraviolet Observations for Nova LMC 1988; (3) Numerical Solution of the Expanding Stellar Atmosphere Problem; (4) A Non-LTE Line-Blanketed Expanding Atmosphere Model for A-supergiant Alpha...
Topics: NASA Technical Reports Server (NTRS), ABSTRACTS, SUPERGIANT STARS, NOVAE, ULTRAVIOLET SPECTRA,...
We present J, H, K spectrally dispersed interferometry with a spectral resolution of 35 for the Mira variable S Orionis. We aim at measuring diameter variation as a function of wavelength that is expected due to molecular layers lying above the continuum-forming photosphere. Our final goal is a better understanding of the pulsating atmosphere and its role in the mass-loss process. Visibility data of S Ori were obtained at phase 0.78 with the VLTI/AMBER instrument. Apparent uniform disk (UD)...
Topics: DTIC Archive, Wittkowski, M, EUROPEAN SOUTHERN OBSERVATORY MUENCHEN (GERMANY), *STELLAR...
Investigations of deviations in local thermodynamic equilibrium in stellar atmospheres are summarized. Included are studies in gray and AO star atmospheres.
Topics: NASA Technical Reports Server (NTRS), STELLAR ATMOSPHERES, THERMODYNAMIC EQUILIBRIUM, ADIABATIC...
The halo of the Milky Way provides unique elemental abundance and kinematic information on the first objects to form in the Universe, and this information can be used to tightly constrain models of galaxy formation and evolution. Although the halo was once considered a single component, evidence for its dichotomy has slowly emerged in recent years from inspection of small samples of halo objects. Here we show that the halo is indeed clearly divisible into two broadly overlapping structural...
Topics: DTIC Archive, Carollo, Daniela, NAVAL OBSERVATORY FLAGSTAFF AZ, *STELLAR ATMOSPHERES, ORBITS,...
Kepler is a Discovery-class mission designed to determine the frequency of Earth-size and smaller planets in and near the habitable zone (HZ) of dwarf stars. The instrument consists of a 0.95-m aperture photometer capable of doing high precision photometry of more than 100,000 late-type main sequence stars to search for patterns of transits. Multi-band ground-based observation of over 2 million stars is currently underway to estimate the stellar parameters and to choose appropriate targets. The...
Topics: DTIC Archive, Borucki, W J, NAVAL OBSERVATORY WASHINGTON DC, *MISSIONS, *DWARF STARS, *PLANETS,...
Surveys of brown dwarf variability continue to find that roughly half of all brown dwarfs are variable. While variability is observed amongst all types of brown dwarfs, amplitudes are typically greatest for L-T transition objects. In my talk I will discuss the possible physical mechanisms that are responsible for the observed variability. I will particularly focus on comparing and contrasting the effects of changes in atmospheric thermal profile and cloud opacity. The two different mechanisms...
Topics: NASA Technical Reports Server (NTRS), BROWN DWARF STARS, VARIABILITY, OPACITY, STELLAR ATMOSPHERES,...
Normal A type stars, nonradiative heating in A type stars, magnetic Ap stars. The Am stars, the delta Scu stars, A supergiants, peculiar B type stars, and model atmospheres are addressed.
Topics: NASA Technical Reports Server (NTRS), A STARS, MAGNETIC STARS, STELLAR ATMOSPHERES, ATMOSPHERIC...
The purpose of this project was to determine the temperatures and luminosities of the individual components of eclipsing binary star systems. The information was gained by UBV photometry of a system at total eclipse and at a time outside eclipse. The light at totality is due entirely to the occulting star, and outside eclipse, both stars contribute fully. A method is derived for subtracting out the light of the occulting star to obtain measurements of the occulted. Systems for which a complete...
Topics: DTIC Archive, Campbell,Robert M, NAVAL ACADEMY ANNAPOLIS MD, *Binary stars, Luminosity, Color...
In anticipation of the possible collision between a circumstellar disk and the secondary star in the highly eccentric binary system Scorpii, high angular resolution interferometric observations have been acquired aimed at revising the binary parameters. The Navy Prototype Optical Interferometer (NPOI) was used to spatially resolve the binary components in 2000 and over a period between 2005 and 2010. The interferometric observations are used to obtain the angular separations and orientations of...
Topics: DTIC Archive, NAVAL OBSERVATORY FLAGSTAFF AZ, *BINARY STARS, *STELLAR ATMOSPHERES, *OPTICAL...
I discuss errors in theory and in interpreting observations that are produced by the failure to consider resolution in space, time, and energy. I discuss convection in stellar model atmospheres and in stars. Large errors in abundances are possible such as the factor of ten error in the Li abundance for extreme Population II stars. Finally I discuss the variation of microturbulent velocity with depth, effective temperature, gravity and abundance. These variations must be dealt with in computing...
Topics: NASA Technical Reports Server (NTRS), STELLAR ATMOSPHERES, ATMOSPHERIC MODELS, ERRORS, FAILURE,...
Surveys by ground based telescopes, HST, and Spitzer have revealed that brown dwarfs of most spectral classes exhibit variability. The spectral and temporal signatures of the variability are complex and apparently defy simplistic classification which complicates efforts to model the changes. Important questions include understanding if clearings are forming in an otherwise uniform cloud deck or if thermal perturbations, perhaps associated with breaking gravity waves, are responsible. If clouds...
Topics: NASA Technical Reports Server (NTRS), BROWN DWARF STARS, VARIABILITY, STELLAR ATMOSPHERES,...
245
245
Jul 6, 2010
07/10
by
VARGA, S
texts
eye 245
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EXAMPLES ARE GIVEN OF THE APPLICABILITY AND IMPORTANCE OF RADIONUCLIDE FLUORESCENCE ANALYSIS AS A METHOD OF INSTRUMENTAL ANALYSIS.
Topics: ASTRONOMICAL MODELS, SOLAR ATMOSPHERE, SPECTRUM ANALYSIS, STELLAR EVOLUTION, ASTROPHYSICS,...
Direct observational evidence of stellar chromospheres is provided by H and K lines and their relationships to mass flux, mechanical dissipation and magnetic fields. Interpretation of half widths of these lines and of the H alpha lines provides indirect indications of potential chromospheric heating in the presence of velocity fields.
Topics: NASA Technical Reports Server (NTRS), CHROMOSPHERE, LINE SPECTRA, SPECTRUM ANALYSIS, STELLAR...
Topics: DTIC Archive, Gurzadyan, G. A., JOINT PUBLICATIONS RESEARCH SERVICE ARLINGTON VA, *FREE ELECTRONS,...
Most of the stellar end-state black holes, pulsars, and white dwarfs that are X-ray sources should have polarized X-ray fluxes. The degree will depend on the relative contributions of the unresolved structures. Fluxes from accretion disks and accretion disk corona may be polarized by scattering. Beams and jets may have contributions of polarized emission in strong magnetic fields. The Gravity and Extreme Magnetism Small Explorer (GEMS) will study the effects on polarization of strong gravity of...
Topics: NASA Technical Reports Server (NTRS), BLACK HOLES (ASTRONOMY), POLARIMETRY, X RAY SOURCES, STELLAR...
Line profiles of 36 multiplets of silicon (Si) II, III, and IV were computed for a grid of model atmospheres covering the range from 15,000 to 35,000 K in effective temperature and 2.5 to 4.5 in log (gravity). The computations involved simultaneous solution of the steady-state statistical equilibrium equations for the populations and of the equation of radiative transfer in the lines. The variables were linearized, and successive corrections were computed until a minimal accuracy of 1/1000 in...
Topics: NASA Technical Reports Server (NTRS), EQUILIBRIUM EQUATIONS, LINE SPECTRA, SILICON, STELLAR...
255
255
Jun 21, 2010
06/10
by
Lachs, M
texts
eye 255
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Space flight effects on international relations and formulation of extraterrestrial space treaty
Topics: ATMOSPHERIC MODELS, THERMODYNAMIC EQUILIBRIUM, MATHEMATICAL MODELS, STELLAR ATMOSPHERES, BALMER...
Described are two basic types of theoretical models - radiative equilibrium and empirical - that are used to represent stellar chromospheres. The construction of radiative-equilibrium model atmospheres that show an outward temperature increase in the surface layers is reported. Also discussed is chromospheric cooling due to spectral lines. Solar empirical models describe the empirical determination of solar-type chromospheric models that, in order to match observations, imply a temperature rise...
Topics: NASA Technical Reports Server (NTRS), ASTRONOMICAL MODELS, CHROMOSPHERE, STELLAR ATMOSPHERES,...
Observations of emission lines in stellar sources in the ultraviolet region of the spectrum show P Cygni-like evidence of mass outflow as well as many ultraviolet emission lines which cannot be interpreted wholly in terms of geometric effects. These are considered powerful chromospheric indicators.
Topics: NASA Technical Reports Server (NTRS), CHROMOSPHERE, LINE SPECTRA, STELLAR ATMOSPHERES, ULTRAVIOLET...
We observed v is equal 1, J equals 1-0 43 GHz SiO maser emission toward the Mira variable IK Tauri (IK Tau) using the Very Long Baseline Array (VLBA). The images resulting from these observations show that SiO masers form a highly elliptical ring of emission approximately 58 x32 mas with an axial ratio of 1.8:1. The major axis of this elliptical distribution is oriented at a position angle of approximately 59 deg. The line-of-sight velocity structure of the SiO masers has an apparent axis of...
Topics: DTIC Archive, Boboltz, D A, NAVAL OBSERVATORY WASHINGTON DC, *MASERS, VELOCITY, SHELLS(STRUCTURAL...
This is an attempt to provide a working bibliography for particular use in preparation for the Fourth Symposium on Cosmical Gas Dynamics: Aerodynamic Phenomena in Stellar Atmospheres
Topics: DTIC Archive, Thomas, R N, NATIONAL BUREAU OF STANDARDS BOULDER CO, *AERODYNAMICS, *STELLAR...
The shock dissipation hypothesis for solar atmospheric heating is extended to stellar chromospheres of late type stars which have significant convective envelopes. Principle wave modes are studied for their generation, propagation, and heating properties in the presence of a magnetic field, and various approximations on when a sound wave becomes strong enough to produce heating in the atmosphere are presented.
Topics: NASA Technical Reports Server (NTRS), CHROMOSPHERE, DYNAMIC MODELS, SHOCK HEATING, STELLAR...
The UV SED parameter b as in f(sub 1) ~ 1(sup b), is commonly used to estimate fundamental properties of high-redshift galaxies including age and metallicity. However, sources and processes other than age and metallicity can influence the value of b. We use the local starforming dwarf galaxy, I Zw 18, in a case study to investigate uncertainties in age and metallicity inferred from b due errors or uncertainties in: mode of star formation (instantaneous starburst vs. continuous SF), dust...
Topics: NASA Technical Reports Server (NTRS), STAR FORMATION, ULTRAVIOLET RADIATION, STELLAR ATMOSPHERES,...
A large collection of white dwarf (WD) spectra from Sloan Digital Sky Survey (SDSS) data release 4 (DR4) WD catalog data allowed us to obtain a luminosity function (LF)for the hottest WDs. The LF was calculated basing on spectra of the WDs from a special class of SDSS objects called hot standards (HS), for which the WD sample completeness can be estimated. WD distances were determined from the observed and absolute SDSS g filter magnitudes derived from WD stellar atmosphere model fits to the...
Topics: DTIC Archive, NAVAL OBSERVATORY FLAGSTAFF AZ, *DWARF STARS, *SPECTRA, ATMOSPHERE MODELS,...
Silicate carbon stars are characterized by oxygen-rich circumstellar environments as revealed by prominent silicate emission, despite their carbon-rich photospheres. While the presence of a circumbinary disk or a disk around an unseen, low-luminosity companion has been suggested to explain the peculiar dust chemistry, the origin of silicate carbon stars is still a puzzle to date. We present multi-epoch, high-angular resolution observations of 22 GHz H2O masers toward the silicate carbon star EU...
Topics: DTIC Archive, Ohnaka, K, NAVAL OBSERVATORY WASHINGTON DC, *SILICATES, *STARS, *CARBON,...
Measurements of alpha Her A with the Amplitude Interferometer yield a uniform disk angular diameter of 0.'058 + or - 0.'009. The fundamental effective temperature, 2450K, obtained from this measurement is in good accord with those of luminous stars of neighboring spectral types, and differs markedly from previous determinations.
Topics: DTIC Archive, Knapp,S L, MARYLAND UNIV COLLEGE PARK DEPT OF PHYSICS AND ASTRONOMY, *SURFACE...
We have enhanced the spectral resolution of the Navy Prototype Optical Interferometer (NPOI) at the H-alpha line to 3 nm (FWHM). We use customized filters that suppresses light in the 600-725 nm window except for light at the H-alpha wavelength (656.3 nm). The bands shortward of 600 nm and longward of 725 nm are used for fringe tracking and for calibrating the system fringe visibility. We have used these filters to observe H-alpha emission from circumstellar material around Be stars. Closure...
Topics: DTIC Archive, Gilbreath, G, NAVAL RESEARCH LAB WASHINGTON DC, *OBSERVATION, *PROTOTYPES, *OPTICAL...
The primary goal of this analysis is to determine whether the effects of atomic bound-bound transitions on stellar atmospheric structure can be represented well in models. The investigation is based on an approach which is called the method of artificial absorption edges. The method is described, developed, tested, and applied to the problem of fitting a model stellar atmosphere to Sirius. It is shown that the main features of the entire observed spectrum of Sirius can be reproduced to within...
Topics: NASA Technical Reports Server (NTRS), ABSORPTION SPECTRA, ATMOSPHERIC MODELS, STELLAR ATMOSPHERES,...
The IUE observations of supernova 1979c in M 100 are presented and discussed. The main results are: (1) the bulk of the energy is in the form of continuous emission which is radiated by the main SN envelope; (2) the absorption features originate mostly in both the disks and the haloes of our Galaxy and M 100; and (3) the emission lines are produced in a highly ionized shell which has a radius greater than twice the radius of the main envelope and consists of compressed circumstellar material in...
Topics: NASA Technical Reports Server (NTRS), EMISSION SPECTRA, SPACEBORNE ASTRONOMY, STELLAR ATMOSPHERES,...
We present the results of a comprehensive assessment of companions to solar-type stars. A sample of 454 stars including the Sun, was selected from the Hipparcos catalog with pi 40 mas, sigma pi/pi 0.05, 0.5 less than or equal to B less than or equal to 1.0 (F6-K3), and constrained by absolute magnitude and color to exclude evolved stars. These criteria are equivalent to selecting all dwarf and subdwarf stars within 25 pc with V-band flux between 0.1 and 10 times that of the Sun giving us a...
Topics: DTIC Archive, GEORGIA STATE UNIV ATLANTA CENTER FOR HIGH ANGULAR RESOLUTION ASTRONOMY, *STARS,...
This grant has supported my GHRS-related activities since 1990. This included both instrumental calibration activities and independent scientific research using the Goddard High Resolution Spectrograph on the Hubble Space Telescope. The activities under this grant are essentially complete. Publications to date which have resulted in whole or in part from this grant are included.
Topics: NASA Technical Reports Server (NTRS), THREE DIMENSIONAL BODIES, COOL STARS, STELLAR ATMOSPHERES,...
601
601
Jul 12, 2010
07/10
by
Wilson, R. B.; Bak, M. J.; Nakazawa, S.; Banerjee, P. K
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A 3-D inelastic analysis methods program consists of a series of computer codes embodying a progression of mathematical models (mechanics of materials, special finite element, boundary element) for streamlined analysis of combustor liners, turbine blades, and turbine vanes. These models address the effects of high temperatures and thermal/mechanical loadings on the local (stress/strain) and global (dynamics, buckling) structural behavior of the three selected components. These models are used...
Topics: ATMOSPHERIC HEATING, TIME SERIES ANALYSIS, X RAY SOURCES, IUE, STELLAR ATMOSPHERES, STELLAR FLARES,...
Information supplementary to that contained in Section 4 of an article entitled, A CO Survey of Regions Around 34 Open Clusters, (Leisawitz, Bash, and Thaddeus) published in the Astrophysical Journal Supplement Series, Volume 70, Number 4, August 1989 is summarized. The information presented here, which describes the interstellar environments of young clusters and some cluster physical characteristics, comes from observations published in the astronomical literature and the author's carbon...
Topics: NASA Technical Reports Server (NTRS), CARBON DIOXIDE, EMISSION SPECTRA, INTERSTELLAR MATTER, OPEN...
Detailed theoretical studies of chromospheric inhomogeneities consider dynamics as well as radiative transfer of mass flow as a consequence of energy deposition. It is shown that pressure is exerted by the heating waves, especially in inhomogeneous structures, where they can be defracted. A dynamical model is formulated that depicts the inhomogeneous structure of the chromosphere-corona transition region through mass flow regimes.
Topics: NASA Technical Reports Server (NTRS), CHROMOSPHERE, INHOMOGENEITY, MASS FLOW, MASS TRANSFER,...
A summary of observations of the angular diameters of the shells around evolved red giants is reported. Many of these sources are partially resolved with a ground-based 2.4-m telescope. We have concentrated our efforts in the 8 - 13 micron spectral range because this corresponds to the emission excesses observed in the spectra of oxygen-rich stars. These excesses are commonly thought to arise from small 'silicate' mineral grains in the circumstellar shells. The shell structure has been fully...
Topics: DTIC Archive, Dyck, H M, WYOMING UNIV LARAMIE DEPT OF PHYSICS AND ASTRONOMY, *ANGLES,...
We report on the results of a number of infrared spectra (0.8-2.5, 2.1-4.6, and 3-14 microns) of V838 Monocerotis, taken from a short time after discovery in 2002 January to about 14 months later, in early 2003. The spectrum evolved dramatically, changing from a quasi-photospheric stellar spectrum with weak atomic emission lines (some with P Cygni profiles) to one showing a wide range of deep absorption features indicative of a cool, extended atmosphere with a circumstellar dust shell. The...
Topics: DTIC Archive, Lynch, David K, AEROSPACE CORP LOS ANGELES CA, *EMISSION, *SPECTROSCOPY, *INFRARED...
375
375
Jul 12, 2010
07/10
by
NON
texts
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Methods are described for using acoustic energy to agglomerate fine particles on the order of one micron diameter that are suspended in gas, to provide agglomerates large enough for efficient removal by other techniques. The gas with suspended particles, is passed through the length of a chamber while acoustic energy at a resonant chamber mode is applied to set up one or more acoustic standing wave patterns that vibrate the suspended particles to bring them together so they agglomerate. Several...
Topics: BINARY STARS, NITROGEN, STELLAR ATMOSPHERES, STELLAR WINDS, TEMPERATURE MEASUREMENT, TRACE...
Models of stellar winds were considered in which the dynamic expansion of a corona is driven by Alfven waves propagating outward along radial magnetic field lines. In the presence of Alfven waves, a coronal expansion can exist for a broad range of reference conditions which would, in the absence of waves, lead to static configurations. Wind models in which the acceleration mechanism is due to Alfven waves alone and exhibit lower mass fluxes and higher energies per particle are compared to wind...
Topics: NASA Technical Reports Server (NTRS), MAGNETOHYDRODYNAMIC WAVES, STELLAR WINDS, ASTRONOMICAL...
Activities are presented for the grant-funded work at the Dominion Astrophysical (DAO) and Casleo Observatories. A comparison is planned for the spectrograms taken at both observatories of similar stars. It is reported that of the Northern Hemisphere program stars, only 112 Her remains to be analyzed. A preliminary solution for the components of this binary system has been found. The new ATLAS9 models have been used to reevaluate the effective temperatures and surface gravities derived for all...
Topics: NASA Technical Reports Server (NTRS), ASTRONOMICAL PHOTOGRAPHY, LINE SPECTRA, SPECTROGRAMS,...
The ubiquitous evidence for processed materials in the atmospheres, winds, and circumstellar ejecta of massive stars is reviewed. A broad array of normal and peculiar evolutionary stages is considered, up to and including Type II supernova progenitors. The quantitative analysis of these spectra is difficult, and until recently for the most part only qualitative or approximate results have been available. However, several important current programs promise reliable abundance calculations. A...
Topics: NASA Technical Reports Server (NTRS), ANOMALIES, HELIUM, HOT STARS, STELLAR ATMOSPHERES, STELLAR...
