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267
Jun 12, 2011
06/11
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Zhu, Dongming; Choi, Sung R.; Miller, Robert A
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Ceramic thermal barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. Durability of the coating systems remains a critical issue with the ever-increasing temperature requirements. Thermal conductivity increase and coating degradation due to sintering and phase changes are known to be detrimental to coating performance. There is a need to characterize the...
Topics: SUPERNOVA REMNANTS, GAMMA RAYS, TITANIUM, RADIOACTIVE DECAY, SPECTRAL LINE WIDTH, STELLAR MODELS,...
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206
May 23, 2011
05/11
by
Lu, Pin
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This research set out to investigate flight control of aircraft which has sustained damage in regular flight control effectors, due to jammed control surfaces or complete loss of hydraulic power. It is recognized that in such an extremely difficult situation unconventional measures may need to be taken to regain control and stability of the aircraft. Propulsion controlled aircraft (PCA) concept, initiated at the NASA Dryden Flight Research Center. represents a ground-breaking effort in this...
Topics: B STARS, EXTREME ULTRAVIOLET RADIATION, X RAY OPTICS, X RAY STARS, CONTINUUMS, NEUTRON STARS,...
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166
Jul 23, 2010
07/10
by
Baram, Yoram; Kailath, Thoma
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eye 166
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A linear state-space system will be said to be estimable if in estimating its state from its output the posterior error covariance matrix is strictly smaller than the prior covariance matrix. It will be said to be regulable if the quadratic cost of state feedback control is strictly smaller than the cost when no feedback is used. These properties, which are shown to be dual, are different from the well known observability and controllability properties of linear systems. Necessary and...
Topics: EMISSION SPECTRA, INFRARED RADIATION, IONIZATION COEFFICIENTS, LINE SPECTRA, ORION NEBULA, STELLAR...
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380
Jul 25, 2010
07/10
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Pototzky, Anthony S.; Spain, Charles V.; Soistmann, David L.; Noll, Thomas E
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A presentation provided at the Fourth National Aerospace Plane Technology Symposium held in Monterey, California, in February 1988 is discussed. The objective is to provide current results of ongoing investigations to develop a methodology for predicting the aerothermoelastic characteristics of NASP-type (hypersonic) flight vehicles. Several existing subsonic and supersonic unsteady aerodynamic codes applicable to the hypersonic class of flight vehicles that are generally available to the...
Topics: ECLIPSING BINARY STARS, IUE, SPACEBORNE ASTRONOMY, ULTRAVIOLET ASTRONOMY, ULTRAVIOLET SPECTRA,...
256
256
May 24, 2011
05/11
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Zhao, Jingxia; Toon, Owen B.; Turco, Richard P
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An enhanced sulfate aerosol layer has been observed near 25 km accompanying springtime ozone depletion in the Antarctic stratosphere. We use a one-dimensional aerosol model that includes photochemistry, particle nucleation, condensational growth, coagulation, and sedimentation to study the origin of the layer. Annual cycles of sunlight, temperature, and ozone are incorporated into the model. Our results indicate that binary homogeneous nucleation leads to the formation of very small droplets of...
Topics: STARBURST GALAXIES, GAS DENSITY, GAMMA RAY SPECTRA, PHOTON DENSITY, MAGNETIC FIELDS, SYNCHROTRONS,...
Binary neutron stars merger (NS(sup 2)M) at cosmological distances is probably the only gamma-ray bursts model based on an independently observed phenomenon which is known to be taking place at a comparable rate. We describe this model, its predictions and some open questions.
Topics: NASA Technical Reports Server (NTRS), BINARY STARS, GAMMA RAY BURSTS, NEUTRON STARS, ASTRONOMICAL...
Ultraviolet and optical data for the Hg Mn stars Coronae Borealis and Cancri is being combined with data for the field horizontal branch population II star HD 109995 in order to derive the element abundances in their photospheres. Data collected by IUE is being utilized.
Topics: NASA Technical Reports Server (NTRS), ABUNDANCE, PHOTOSPHERE, STARS, IRON, IUE, LINE SPECTRA,...
139
139
Jun 11, 2011
06/11
by
Huntington, Geoffrey; Rao, Anil V.; Hughes, Steven P
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The problem of minimum-fuel formation reconfiguration for the Magnetospheric Multi-Scale (MMS) mission is studied. This reconfiguration trajectory optimization problem can be posed as a nonlinear optimal control problem. In this research, this optimal control problem is solved using a spectral collocation method called the Gauss pseudospectral method. The objective of this research is to provide highly accurate minimum-fuel solutions to the MMS formation reconfiguration problem and to gain...
Topics: MORPHOLOGY, IMAGES, CONDUCTIVE HEAT TRANSFER, RADIO EMISSION, SUPERNOVA REMNANTS, X RAY...
Taken at face value, the observed properties of the central object in Eta-Car suggest a very massive, hot main-sequence star, only slightly evolved. If this is so, the star's extraordinarily high steady rate of mass loss must dynamically perturb its outer envelope down to the iron convection zone, where the kinetic energy associated with turbulent convection can be directly fed into mass ejection. Runaway mass loss, triggered by either internal (pulsational, rotational) or external (tidal)...
Topics: NASA Technical Reports Server (NTRS), CONVECTION, MASSIVE STARS, OSCILLATIONS, BLUE STARS, STELLAR...
The observational status of the line profile variable B stars is summarized. The following areas are discussed: recent history; evolutionary status; line profile variations; line strength variations; and photometric variations.
Topics: NASA Technical Reports Server (NTRS), CEPHEUS CONSTELLATION, LINE SPECTRA, VARIABLE STARS,...
We construct evolutional scenarios for LMXB's using a simplified stellar model. We discuss the origin and evolution of short-period, low mass binary pulsars with evaporating companions. We suggest that these systems descend from low-mass X-ray binaries and that angular momentum loss mainly due to evaporative wind drives their evolution. We derive limits on the energy and angular momentum carried away by the wind based on the observed low eccentricity. In our model the companion remains near...
Topics: NASA Technical Reports Server (NTRS), ANGULAR MOMENTUM, MASS, PULSARS, ROCHE LIMIT, STELLAR MODELS,...
According to the prevailing core instability model, giant planets begin their growth by the accumulation of small solid bodies, as do terrestrial planets. However, unlike terrestrial planets, the growing giant planet cores become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. Models predict that rocky planets should form in orbit about most stars. It is uncertain whether or not gas giant planet formation is common, because...
Topics: NASA Technical Reports Server (NTRS), BROWN DWARF STARS, GAS GIANT PLANETS, PLANETARY EVOLUTION,...
A dynamical model was proposed which is in agreement with the observations that suggest the solar chromosphere is heated preferentially in magnetic regions. The dynamical model requires an energy flux that is large enough to lead to amplitudes for which the apparent temperatures match the empirical line temperatures in the UTV lines. Consistency with the observations of chromospheric emission then requires that the emission take place not uniformly over the solar surface but in smaller spatial...
Topics: NASA Technical Reports Server (NTRS), CHROMOSPHERE, STELLAR MODELS, SUN, TIME DEPENDENCE,...
Some Be stars which are intermittent C-ray sources may have white dwarf companions rather than neutron stars. It is not possible to prove or rule out the existence of Be+WD systems using X-ray or optical data. However, the presence of a white dwarf could be established by the detection of its EUV continuum shortward of the Be star's continuum turnover at 1OOOA. Either the detection or the nondetection of Be+WD systems would have implications for models of Be star variability, models of Be...
Topics: NASA Technical Reports Server (NTRS), B STARS, EXTREME ULTRAVIOLET RADIATION, X RAY OPTICS, X RAY...
The discovery of presolar grains in meteorites is one of the most exciting recent developments in meteoritics. Six types of presolar grain have been discovered: diamond, Sic, graphite, Si3N4, Al2O3 and MgAl2O4. These grains have been identified as presolar because their isotopic compositions are very different from those of Solar System materials. Comparison of their isotopic compositions with astronomical observations and theoretical models indicates most of the grains formed in the envelopes...
Topics: NASA Technical Reports Server (NTRS), METEORITES, SILICON NITRIDES, METEORITIC COMPOSITION,...
The following three publications which reference the above grant from the NASA Origins of Solar Systems program are attached and form the final technical report for this project. The research involved comparisons of the spectral energy distributions of FU Orionis objects with theoretical models and associated studies of the structure of the outbursting accretion disks, as well as related studies on the effects of magnetic fields in disks, which will lead in the future to models of FU Orionis...
Topics: NASA Technical Reports Server (NTRS), SPECTRAL ENERGY DISTRIBUTION, ORION CONSTELLATION,...
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273
May 26, 2011
05/11
by
Lollar, Louis F.; Maus, Louis C
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Marshall Space Flight Center (MSFC) is the National Aeronautics and Space Administration's (NASA) lead center for space transportation systems development. These systems include earth to orbit launch vehicles, as well as vehicles for orbital transfer and deep space missions. The tasks for these systems include research, technology maturation, design, development, and integration of space transportation and propulsion systems. One of the key elements in any transportation system is the...
Topics: BINARY STARS, TRAJECTORIES, STELLAR WINDS, MASS TRANSFER, ASYMPTOTIC GIANT BRANCH STARS, STELLAR...
Gamma-ray binaries are stellar systems containing a neutron star or black hole, with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy, A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL ]1018.6-5856 exhibits intensity and spectral modulation with a 16.6 day period. We identified a variable x-ray counterpart, which shows a sharp maximum coinciding...
Topics: NASA Technical Reports Server (NTRS), BINARY STARS, GAMMA RAYS, STELLAR MODELS, STELLAR SYSTEMS,...
The physics of coronal transients, the characteristics of radiation and accelerated particles at the time of flares, and the density/temperature structure of the transition region and corona and the coronal magnetic field are investigated.
Topics: NASA Technical Reports Server (NTRS), ACCELERATION (PHYSICS), ASTROPHYSICS, SOLAR CORONA, SOLAR...
1,147
1.1K
May 29, 2011
05/11
by
NON
texts
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An improved reciprocating internal combustion engine has a plurality of engine pistons, which are fabricated from carbon-carbon composite materials, in operative association with an engine cylinder block, or an engine cylinder tube, or an engine cylinder jug, all of which are also fabricated from carbon-carbon composite materials.
Topics: COSMIC BACKGROUND EXPLORER SATELLITE, ZODIACAL DUST, STELLAR MODELS, GALACTIC STRUCTURE, SKY...
Some braneworld models may have observable consequences that, if detected, would validate a requisite element of string theory. In the infinite Randall-Sundrum model (RS2), the AdS radius of curvature, L, of the extra dimension supports a single bound state of the massless graviton on the brane, thereby reproducing Newtonian gravity in the weak-field limit. However, using the AdS/CFT correspondence, it has been suggested that one possible consequence of RS2 is an enormous increase in Hawking...
Topics: NASA Technical Reports Server (NTRS), BLACK HOLES (ASTRONOMY), GRAVITATIONAL WAVES, GRAVITONS,...
Supernova mechanisms in accreting white dwarfs are considered with emphasis on deflagration as a plausible mechanism for producing Type I supernovae and electron captures to form quiet supernovae leaving neutron stars. These outcomes depend on accretion rate of helium, initial mass and composition of the white dwarf. The various types of hydrogen shell burning in the presupernova stage are also discussed.
Topics: NASA Technical Reports Server (NTRS), NEUTRON STARS, STELLAR MASS ACCRETION, SUPERNOVAE, WHITE...
We study the rotational distortions of the vacuum dipole magnetic field in the context of geometrical models of the radio emission from pulsars. We find that at low altitudes the rotation deflects the local direction of the magnetic field by at most an angle of the order of r(sup 2 sub n), where r(sub n) = r/R(sub lc), r is the radial distance and R(sub lc) is the light cylinder radius. To the lowest (i.e. second) order in r(sub n) this distortion is symmetrical with respect to the plane...
Topics: NASA Technical Reports Server (NTRS), PULSAR MAGNETOSPHERES, STELLAR ROTATION, RADIO EMISSION,...
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207
May 23, 2011
05/11
by
Duran, R. S
texts
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The overall objective of this study was the description of the behavior of mesogen substituted acetylene monomers and polymers in monolayer films at the air/water interface and as multilayer films including the formation of such films. Fundamental knowledge to be gained would include the effect of balancing hydrophilic and hydrophobic tendencies in a molecule more complex than the classical fatty acids or lipids. The effect of molecular shape on the packing and thus the ultimate stability of...
Topics: CHROMOSPHERE, PHOTOSPHERE, MAGNETOHYDRODYNAMIC WAVES, FLUX (RATE), ENERGY TRANSFER, STELLAR MODELS,...
1,349
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May 22, 2011
05/11
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NON
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The following are presented: The National Advisory Committee for Aeronautics Charter; Exploring NASA's Roots, the History of NASA Langley Research Center; NASA Langley's National Historic Landmarks; The Mustang Story: Recollections of the XP-51; Testing the First Supersonic Aircraft: Memoirs of NACA Pilot Bob Champine; NASA Langley's Contributions to Spaceflight; The Rendezvous that was Almost Missed: Lunar Orbit Rendezvous and the Apollo Program; NASA Langley's Contributions to the Apollo...
Topics: LYMAN ALPHA RADIATION, STELLAR RADIATION, TWO DIMENSIONAL MODELS, ULYSSES MISSION,...
Results on V356 Sgr from IUE and Voyager ultraviolet (500 to 3200 A) observations obtained in 1986 and 1987, primarily during 2 total eclipses are presented. The eclipse of Aug. 15, 1986 was fully covered with IUE low dispersion images and 9 hr of Voyager UVS data. The eclipse of Mar. 25, 1987 was covered with IUE low dispersion images and 1 high dispersion SWP image. During both eclipses the total strength of the emission lines is found to be invariant. An uneclipsed UV continuum is detected...
Topics: NASA Technical Reports Server (NTRS), ECLIPSING BINARY STARS, IUE, SPACEBORNE ASTRONOMY,...
Transient disturbances in the solar wind initiated by coronal eruptions have been modeled for many years, beginning with the self-similar analytical models of Parker and Simon and Axford. The first numerical computer code (one-dimensional, gas dynamic) to study disturbance propagation in the solar wind was developed in the late 1960s, and a variety of other codes ranging from simple one-dimensional gas dynamic codes through three-dimensional gas dynamic and magnetohydrodynamic codes have been...
Topics: NASA Technical Reports Server (NTRS), STELLAR MODELS, CORONAL MASS EJECTION, SOLAR WIND, EVOLUTION...
The purpose of this INTEGRAL AO 1 proposal was to observe the gamma-ray lines at 1157 keV, as well as 68 keV and 78 keV of the (44)Ti decay chain from the youngest known galactic supernova remnant Cas A. The radioactive decay of (44)Ti in Cas A was first detected by COMPTEL in the 1157 keV line and later confirmed in the lower energy lines using BeppoSAX data. Despite the second confirming measurement, the flux value still has a considerable error, due to a low signal over background ratio and...
Topics: NASA Technical Reports Server (NTRS), SUPERNOVA REMNANTS, GAMMA RAYS, TITANIUM, RADIOACTIVE DECAY,...
We strongly disagree with the essence of the Osherovich (hereafter Osherovich) comment on one of our papers. The following paragraphs provide the basis of our disagreement and elaborate on why we believe that none of the concluding statements in his Comment are true. Our most important point is that one can apply the model developed by Osherovich and colleagues to real data obtained at a single point in space to determine the polytropic index within magnetic clouds if and only if the highly...
Topics: NASA Technical Reports Server (NTRS), CORONAL MASS EJECTION, SOLAR WIND, STELLAR MODELS, POLYTROPIC...
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209
May 31, 2011
05/11
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NON
texts
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IFOS developed the ISense technology with assistance from a NASA Langley Research Center SBIR contract. NASA and IFOS collaborated to create sensing network designs that have high sensitivity, low power consumption, and significant potential for mass production. The joint- research effort led to the development of a module that is rugged, compact and light-weight, and immune to electromagnetic interference. These features make the ISense multisensor arrays favorable for smart structure...
Topics: NEUTRON STARS, STELLAR MODELS, OSCILLATIONS, X RAY STARS, STELLAR ROTATION, GAMMA RAY BURSTS, X RAY...
The structure of the Mira variables is discussed with particular emphasis on the extent of their observable atmospheres, the various methods for measuring the sizes of these atmospheres, and the manner in which the size changes through the cycle. The results obtained by direct, photometric and spectroscopic methods are compared, and the problems of interpretation are addressed. Also, a simple model for the atmospheric structure and motions of Miras based on recent observations of the doubling...
Topics: NASA Technical Reports Server (NTRS), GIANT STARS, MIRA VARIABLES, STELLAR ATMOSPHERES, STELLAR...
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219
May 31, 2011
05/11
by
NON
texts
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The Automatic Particle Fallout Monitor (APFM) is an automated instrument that assesses real-time particle contamination levels in a facility by directly imaging, sizing, and counting contamination particles. It allows personnel to respond to particle contamination before it becomes a major problem. For NASA, the APFM improves the ability to mitigate, avoid, and explain mission-compromising incidents of contamination occurring during payload processing, launch vehicle ground processing, and...
Topics: STELLAR MODELS, GEOMETRY, HIGH TEMPERATURE PLASMAS, SPECTRAL ENERGY DISTRIBUTION, SEYFERT GALAXIES,...
273
273
May 23, 2011
05/11
by
Carins, Iver H.; Grabbe, Crockett L
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A magnetohydrodynamic (MHD) theory is developed for the standoff distance a(s) of the bow shock and the thickness Delta(ms) of the magnetosheath, using the empirical Spreiter et al. relation Delta(ms) = kX and the MHD density ratio X across the shock. The theory includes as special cases the well-known gasdynamic theory and associated phenomenological MHD-like models for Delta(ms) and As. In general, however, MHD effects produce major differences from previous models, especially at low Alfev...
Topics: BACKGROUND RADIATION, STELLAR MODELS, ULTRAVIOLET TELESCOPES, GUNN EFFECT, HELIUM, HYDROGEN,...
Experience gained by use of Cepheid modeling codes to predict the dimensional and photometric behavior of nuclear fireballs is used as a means of validating various computational techniques used in the Cepheid codes. Predicted results from Cepheid models are compared with observations of the continuum and lines in an effort to demonstrate that the atmospheric phenomena in Cepheids are quite complex but that they can be quantitatively modeled.
Topics: NASA Technical Reports Server (NTRS), CEPHEID VARIABLES, LIGHT CURVE, NUCLEAR EXPLOSIONS, STELLAR...
The Normal Incidence X-ray Telescope (NIXT) obtained a unique set of high resolution full disk solar images which were exposed simultaneously by X-rays in a passband at 63.5 A and by visible light. The perfect alignment of a photospheric visible light image with a coronal X-ray image enables us to present observations of X-ray intensity vs an accurately determined height above the visible limb. The height at which the observed X-ray intensity peak varies from 4000 km in active regions to 9000...
Topics: NASA Technical Reports Server (NTRS), CHROMOSPHERE, CORONAS, PLASMA DYNAMICS, SOLAR ATMOSPHERE,...
The observed period changes are explained with respect to the behavior of the semiconductive zone (SCZ) within the core of an RR Lyrae star. General consideration are given which suggest that the composition changes occuring within the SCZ during the horizontal-branch evolution result from many small mixing events, each of which slightly perturbs the pulsation period. Results indicate that small mixing events within the core of an RR Lyrae star can produce changes in the pulsation period...
Topics: NASA Technical Reports Server (NTRS), LYRA CONSTELLATION, PERIODIC VARIATIONS, STELLAR EVOLUTION,...
We discuss whether with new evolutionary tracks we still have a problem fitting the Cepheids and their evolved companions on the appropriate evolutionary tracks. We find that with the Bertelli et al. tracks with convective overshoot by one pressure scale height the problem is essentially removed, though somewhat more mixing would give a better fit. By using the results of recent nonlinear hydrodynamic calculations, we find that we also have no problem matching the observed pulsation periods of...
Topics: NASA Technical Reports Server (NTRS), CEPHEID VARIABLES, STELLAR EVOLUTION, STELLAR MASS, STELLAR...
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116
May 23, 2011
05/11
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Litt, Jonathan; Hickman, Andre; Guo, Ten-Hue
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A new robust, optimal, adaptive technique for compensating rate and position limits in the joints of a six degree-of-freedom elbow manipulator is presented. In this new algorithm, the unmet demand as a result of actuator saturation is redistributed among the remaining unsaturated joints. The scheme is used to compensate for inadequate path planning, problems such as joint limiting, joint freezing, or even obstacle avoidance, where a desired position and orientation are not attainable due to an...
Topics: NEUTRON STARS, TROPICAL REGIONS, STAR FORMATION, STAR CLUSTERS, PROBABILITY THEORY, HYDROGEN,...
Previous work has shown that the cooling of SN 1987A excludes a Dirac-neutrino mass greater than theta(20 keV) for nu(sub e), nu(sub mu), or nu(sub tau). The emission of wrong-helicity, Dirac neutrinos from SN 1987A, is re-examined. It is concluded that the effect of a Dirac neutrino on the cooling of SN 1987A has been underestimated due to neutrino degeneracy and additional emission processes. The limit that follows from the cooling of SN 1987A is believed to be greater (probably much greater)...
Topics: NASA Technical Reports Server (NTRS), COOLING, NEUTRINOS, PARTICLE MASS, STELLAR MODELS, STELLAR...
The first unassociated gamma-ray source was discovered by SAS-2 in 1973 (Kniffen, et al., 1975) and later confirmed by COS-B (Bennett, et al., 1977). Followed the announcement, there were numerous attempts to find a counterpart, and many models were developed to explain the source. Now over fifteen years later this illusive source still remains as one of the major riddles of astrophysics. The question of why an object, which is able to emit such energetic photons is so well concealed at other...
Topics: NASA Technical Reports Server (NTRS), ASTROPHYSICS, ENERGETIC PARTICLES, GAMMA RAYS, PHOTONS,...
The thermodynamics of stellar atmospheres is discussed. Particular attention is given to the relation between theoretical modeling and empirical evidence. The characteristics of distinctive atmospheric regions and their radical structures are discussed.
Topics: NASA Technical Reports Server (NTRS), ASTROPHYSICS, STELLAR ATMOSPHERES, STELLAR ENVELOPES, STELLAR...
Empirical models for emission from stars and the ISM are subtracted from the zodiacal-light-subtracted DIRBE 3.5 pm emission. Because the models are contaminated by unknown levels of the CM at other near-IR wavelength, the residual is not simply the 3.5 Jim Cosmic IR Background, but a linear combination of the background levels at several wavelengths. In spite of this, the residual can be used to place limits on the near-IR CIB intensity if its spectral shape is assumed. Additionally, the...
Topics: NASA Technical Reports Server (NTRS), COSMIC RAYS, BACKGROUND RADIATION, STELLAR MODELS, ZODIACAL...
An amalgamation of two published works that discuss the observation and theoretical calculations of OV (T approx. 250,000K) and Hard X-rays (30 to 100keV) emitted during flares are presented. The papers are by Poland et al (1984) and Mariska and Poland (1985). The observations of Hard X-rays and OV show that the excitation processes for each type of emission are closely coupled. Except for small differences the two types of emission rise and fall together during a flare. Model calculations are...
Topics: NASA Technical Reports Server (NTRS), ENERGY TRANSFER, OXYGEN SPECTRA, SOLAR FLARES, SOLAR X-RAYS,...
In order to enhance physical insight into the nature of thermal oscillations arising from a thin helium burning shell, the behavior in its phase plane of a simple two zone model which, however, contains all the relevant physics is analyzed. This simple model very naturally reproduces thermal flickers and is relatively insensitive to all but two parameters.
Topics: NASA Technical Reports Server (NTRS), B STARS, FLICKER, RADIATIVE TRANSFER, STELLAR MODELS,...
The results of comparisons of the solar flux models are presented. (The wavelength lambda = 10.7 cm radio flux is the best indicator of the strength of the ionizing radiations such as solar ultraviolet and x-ray emissions that directly affect the atmospheric density thereby changing the orbit lifetime of satellites. Thus, accurate forecasting of solar flux F sub 10.7 is crucial for orbit determination of spacecrafts.) The measured solar flux recorded by National Oceanic and Atmospheric...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC DENSITY, FORECASTING, ORBIT CALCULATION,...
Multi-color surface photometry (BVri) is presented for the tidal features in a sample of interacting galaxies. Large color variations are found between the morphological components and within the individual components. The blue colors in the primary and the tidal features are most dramatic in B-V, and not in V-i, indicating that star formation instead of metallicity or age dominates the colors. Color variations between components is larger in systems shortly after interaction begins and...
Topics: NASA Technical Reports Server (NTRS), INTERACTING GALAXIES, PHOTOMETRY, STAR FORMATION, STAR...
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May 23, 2011
05/11
by
Cho, Y. C.; Ingard, K. Un
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This paper presents a method of evaluation of Wiener-Hopf technique solutions for sound radiation from an unflanged circular duct with infinitely thin duct wall, including mean flows.
Topics: STELLAR MASS, CALIBRATING, EARLY STARS, HOT STARS, MAGELLANIC CLOUDS, SPECTROSCOPY, STAR CLUSTERS,...
Atomic and molecular physics of supernovae is discussed with an emphasis on the importance of detailed treatments of the critical atomic and molecular processes with the best available atomic and molecular data. The observations of molecules in SN 1987A are interpreted through a combination of spectral and chemical modelings, leading to strong constraints on the mixing and nucleosynthesis of the supernova. The non-equilibrium chemistry is used to argue that carbon dust can form in the...
Topics: NASA Technical Reports Server (NTRS), SUPERNOVAE, ATOMIC PHYSICS, MOLECULAR DYNAMICS, STELLAR...
This grant was awarded by NASA to The University of Alabama in Huntsville (UAH) to construct state-of-the-art, theoretical, two-component, chromospheric models for single stars of different spectral types and different evolutionary status. In our proposal, we suggested to use these models to predict the level of the "basal flux", the observed range of variation of chromospheric activity for a given spectral type, and the decrease of this activity with stellar age. In addition, for red...
Topics: NASA Technical Reports Server (NTRS), STELLAR EVOLUTION, ASTROPHYSICS, CHROMOSPHERE, CORONAS, WIND...
The Fermi Large Area Telescope, in collaboration with several groups from the radio community. have had marvelous success at uncovering new gamma-ray millisecond pulsars (MSPs). In fact, MSPs now make up a sizable fraction of the total number of known gamma-ray pulsars. The MSP population is characterized by a variety of pulse profile shapes, peak separations, and radio-to-gamma phase lags, with some members exhibiting nearly phase-aligned radio and gamma-ray light curves (LCs). The MSPs' short...
Topics: NASA Technical Reports Server (NTRS), GAMMA RAYS, FERMI GAMMA-RAY SPACE TELESCOPE, STELLAR MODELS,...
