ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • ASTROPHYSICS  (811)
  • AERODYNAMICS  (764)
  • 1995-1999
  • 1985-1989
  • 1980-1984
  • 1975-1979  (1,575)
  • 1940-1944
  • 1978  (760)
  • 1977  (815)
Collection
Keywords
Years
  • 1995-1999
  • 1985-1989
  • 1980-1984
  • 1975-1979  (1,575)
  • 1940-1944
Year
  • 1
    facet.materialart.
    Unknown
    Transonic/supersonic inlet R and D past, present, and future (1977)
    In:  CASI
    Details
    Publication Date: 2004-10-07
    Keywords: AERODYNAMICS
    Type: NASA Lewis Research Center Inlet Workshop; p 427-480
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Gamma rays, cosmic rays, and galactic structure (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: Observations of cosmic and gamma radiation by SAS-2 satellite are summarized and analyzed to determine processes responsible for producing observed galactic radiation. In addition to the production of gamma rays in discrete galactic objects such as pulsars, there are three main mechanisms by which high-energy (greater than 100 MeV) radiation is produced by high-energy interactions involving cosmic rays in interstellar space. These processes, which produce what may be called diffuse galactic gamma-rays, are: (1) the decay of pi mesons produced by interactions of cosmic ray nucleons with interstellar gas nuclei; (2) the bremsstrahlung radiation produced by cosmic ray electrons interacting in the Coulomb fields of nuclei of interstellar gas atoms; and (3) Compton interactions between cosmic ray electrons and low-energy photons in interstellar space.
    Keywords: ASTROPHYSICS
    Type: The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 315-346
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Gamma rays and large scale galactic structure (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: Gamma ray astronomy is now beginning to provide a new look at the galactic structure and the distribution of cosmic rays, both electrons and nucleons, within the galaxy. The observations are consistent with a galactic spiral-arm model in which the cosmic rays are linearly coupled to the interstellar gas on the scale of the spiral arms. The agreement between the predictions of the model and the observations for regions of the plane where both 21-cm and 2.6-mm CO surveys exist emphasizes the need to extend these observations to include the entire plane. Future gamma-ray observations with more sensitivity and better angular resolutions, combined with these radio surveys, should shed new light on the distribution of cosmic rays, the nature of the galaxy, and the location and intensity of the spiral arms.
    Keywords: ASTROPHYSICS
    Type: The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 301-314
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Galactic distribution of pulsars (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: The density distributions of pulsars in luminosity, period, Z-distance, and galactocentric distance were derived, using a uniform sample of pulsars detected during a 408-MHz pulsar survey at Jodrell Bank. There are indications of a fine-scale structure in the spatial distributions and evidence that there is a general correlation with other galactic populations and the overall spiral structure. The electron layer in our galaxy is shown to be wider than the pulsar layer and uniform on a large scale. The number of pulsars in the galaxy has been estimated and used to derive the pulsar birthrate.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 265-282
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Gamma rays and supernova explosions (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: Thermal radiation associated with the explosion of supernovae is investigated. High temperature is required to produce copious gamma radiation of this sort. It appears that type 11 supernovae do not release much of their energy as gamma ray continuum radiation.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 257-264
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    Remarks on the overall distribution of hydrogen in the galactic disk (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: The degree of saturation characterizing low altitude emission observations of H(I) and the optical depth corrections to the derived column and volume densities are discussed. The amount of fine-scale velocity and spatial structure diluted by the instrumental limitations of the presently available surveys are described. The general problem of detailed mapping of H(I) in the galaxy is explored. Comparison is made between the distribution of H(I) and that of CO and several other galactic tracers. Atomic hydrogen is unique in its distribution, instead of being typical of many Population I constituents. As defined by atomic hydrogen, the galactic disk has a diameter fully twice as large as that defined by the ionized and molecular states of hydrogen, as well as by other molecules, supernova remnants, pulsars, gamma-radiation, synchroton radiation, and the youngest stars. It is also less confined to the galactic equator than most of the other constituents. The degree of small scale structure apparent in the molecular observations is much greater than that in the H(I) observations.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 163-188
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Gamma ray pulsars (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: Data from the SAS-2 high-energy gamma-ray experiment reveal the existence of four pulsars emitting photons above 35 MeV. An attempt is made to explain the gamma-ray emission from these pulsars in terms of an electron-photon cascade that develops in the magnetosphere of the pulsar. Although there is very little material above the surface of the pulsar, the very intense magnetic fields (10 to the 12th power gauss) correspond to many radiation lengths which cause electrons to emit photons by magnetic bremsstrahlung and which cause these photons to pair-produce. The cascade develops until the mean photon energy drops below the pair-production threshold which is in the gamma-ray range; at this stage, the photons break out from the source.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 109-118
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    Radiation mechanisms and magnetospheric structure of pulsars (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: Considerations made in developing a model of pulsars are explored. Observational data seems to support the argument that pulsar magnetospheres may contain large masses of plasma. The cascade process resulting from pair creation enables one to interpret the X-ray emission from the Crab and Vela pulsars as synchrotron radiation. On the other hand, the optical radiation from the Crab pulsar is best understood as coherent curvature radiation. Radio emission is interpreted as curvature radiation produced by charge bunches moving along magnetic-field lines. Certain tests of this model are proposed.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 99-108
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    Comments on wind-tunnel-flight correlations for the F-8 supercritical wing configurations (1977)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Keywords: AERODYNAMICS
    Type: Supercritical Wing Technol.: A Report on Flight Evaluation; p 111-120
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    A parametric experimental study of the slotted-wall boundary condition (1978)
    In:  CASI
    Details
    Publication Date: 2006-02-22
    Description: An experimental study of slotted upper and lower walls in a two dimensional transonic wind tunnel with solid sidewalls is reported. Results are presented for several slot spacings and slot openness ratios. The experimental data were pressure measurements which were made on an airfoil model and on a sidewall near one of the slotted walls. The slotted-wall boundary condition coefficient, which related the pressure and streamline curvature near the wall, was determined from the wall pressure measurements. The measured wall-induced interference was correlated with the experimental values for the boundary condition coefficient. This correlation was compared with theory.
    Keywords: AERODYNAMICS
    Type: Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 459-471
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 11
    facet.materialart.
    Unknown
    A procedure for analyzing transonic flow over harmonically oscillating airfoils (1978)
    In:  CASI
    Details
    Publication Date: 2006-02-22
    Description: Finite difference procedures were successfully used to solve the steady transonic flow about airfoils and appear to provide a practical means for calculating the corresponding unsteady flow. The purpose of the paper is to describe a finite difference procedure derived from the equations for the potential flow by assuming small perturbations and harmonic motion. The velocity potential is divided into steady and unsteady parts, and the resulting unsteady equation is linearized on the basis of small amplitudes of oscillation. The steady velocity potential, which must be calculated first, is described by the classical nonlinear transonic differential equation.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 657-670
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 12
    facet.materialart.
    Unknown
    Section drag coefficients from pressure probe transverses of a wing wake at low speeds (1978)
    In:  CASI
    Details
    Publication Date: 2006-02-22
    Description: An in-flight wing wake section drag investigation was conducted using traversing pitot and static probes. The primary objective was to develop measurement techniques and improve the accuracy of in-flight wing profile drag measurements for low values of dynamic pressure and Reynolds number. Data were obtained on a sailplane for speeds from about 40 knots to 125 knots at chord Reynolds numbers between 1,000,000 and 3,000,000. Tests were conducted with zero flap deflection, deflected flaps, and various degrees of surface roughness, and for smooth and rough atmospheric conditions. Several techniques were used to increase data reliability and to minimize certain bias errors. A discussion of the effects of a total pressure probe in a pressure gradient, and the effects of discrete turbulence levels, on the data presented and other experimental results is also included.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 601-621
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 13
    facet.materialart.
    Unknown
    Some calculations of transonic potential flow for the NACA 64A006 airfoil with oscillating flap (1978)
    In:  CASI
    Details
    Publication Date: 2006-02-22
    Description: A method for calculating the transonic flow over steady and oscillating airfoils was developed by Isogai. It solves the full potential equation with a semi-implicit, time-marching, finite difference technique. Steady flow solutions are obtained from time asymptotic solutions for a steady airfoil. Corresponding oscillatory solutions are obtained by initiating an oscillation and marching in time for several cycles until a converged periodic solution is achieved. In this paper the method is described in general terms, and results are compared with experimental data for both steady flow and for oscillations at several values of reduced frequency. Good agreement for static pressures is shown for subcritical speeds, with increasing deviation as Mach number is increased into the supercritical speed range. Fair agreement with experiment was obtained at high reduced frequencies with larger deviations at low reduced frequencies.
    Keywords: AERODYNAMICS
    Type: Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 689-700
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 14
    facet.materialart.
    Unknown
    Applications of dynamic measurement techniques to wind-tunnel testing (1978)
    In:  CASI
    Details
    Publication Date: 2006-02-22
    Description: The uses of laser Doppler velocimeter, hot wire, and surface hot film techniques in the study of turbulent flows are described, and data obtained in compressible flows are discussed. Applications are illustrated with measurements of wind tunnel freestream turbulence characteristics and with data obtained in transitional, turbulent, and separated shear flows. A new method which was developed for the study of time dependent and unsteady turbulent flows is also presented.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 571-588
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 15
    facet.materialart.
    Unknown
    Aircraft (1977)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The physical principles of flight, and the consideration of atmospheric composition and aerodynamic forces in the design and construction of various types of aircraft are discussed. Flight characteristics are described for helicopters, rotary-wing aircraft, short and vertical takeoff aircraft, and tailess or variable geometry wing aircraft. Flow characteristics at various speeds are also discussed.
    Keywords: AERODYNAMICS
    Type: Soviet Aircraft and Rockets (NASA-TT-F-770); p 24-80
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 16
    facet.materialart.
    Unknown
    The case for a burst from 3U 0614+09 (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A single flare event with a rise time of about 7 s and a decay time of approximately 40 s was observed by the Goddard cosmic X-ray spectroscopy experiment on OSO-8 during observations of 3U 0614+09 in September 1975. The possibility is discussed that the source was 3U 0614+09, which has been compared with the low-mass binary Sco X-1. The spectra during the event could be fitted with blackbody (kT = 0.8-1.1 keV) or thermal bremsstrahlung (kT = 1.1-2.5 keV) models with absorption by cool material. In the blackbody model the source was of the order of 1 million cm in size.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 182
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 17
    facet.materialart.
    Unknown
    Formation of a rotational accretion column (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: We consider the problem of the flow produced by the accretion of gas from a rotating cloud onto a point gravitational source. It is shown that, for a cloud initially in uniform rotation, the effect of accretion is to produce a Taylor column in the cloud parallel to the rotation axis. Only gas within the column is accreted; the gas outside the column undergoes oscillatory flow, which is probably subject to shear instability. The column forms in approximately one-half rotation period from the time at which accretion begins. Its initial radius is determined by the accretion rate and the angular velocity of the cloud. Application of the results to the formation of Jupiter by accretion is discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 219
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 18
    facet.materialart.
    Unknown
    Primeval gas clouds and the low-energy X-ray background (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A model for the appearance of the all-sky low-energy X-ray background on a fine angular scale is presented which is based on primeval hot gas clouds associated with the formation of clusters of galaxies according to the Sunyaev-Zel'dovich (1972) model. It is noted that the background could have both granular and diffuse components if it is due to such gas clouds. The observed appearance of the granular component is predicted along with the observable characteristics of collapsing protoclusters. The effects of distant X-ray-emitting QSOs, radio galaxies, and normal galaxies on the observations are considered, and these sources are shown not to interfere with the possibility of observing the protoclusters. It is concluded that if sufficient heating occurred in an intracluster medium within some clusters of galaxies at the protocluster epoch, the ensemble properties of protoclusters could be observed with an X-ray telescope, and the time at which protoclusters formed could perhaps be estimated.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 218
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 19
    facet.materialart.
    Unknown
    An experimental investigation of the condensation of silicate grains (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Results are presented for a series of laboratory experiments designed to investigate the nucleation of small silicate grains from a vapor of astrophysically significant elements and compounds. In the experiments, magnesium silicate grains were condensed by simultaneously evaporating Mg and SiO solids into an atmosphere of argon or hydrogen at a pressure of a few torr. The results show that at low temperatures (up to a few hundred degrees C) the condensates are amorphous grains and have widely varying stoichiometries. The thermodynamically most stable compounds (Mg2SiO4, MgSiO3, SiO2) do not form readily, but all initial condensates can be converted to crystalline forsterite (Mg2SiO4) by heating to 1000 C in vacuum. At higher temperatures (above 700 K) it becomes more difficult to nucleate any silicates, and those that do form are amorphous, indicating that surface energies and kinetic effects are very important in determining under what conditions condensation will occur. The IR spectra of the experimentally produced magnesium silicates are found to have a strong resemblance to those observed in many astronomical clouds.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 222
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 20
    facet.materialart.
    Unknown
    Soft X-ray emission from a newly discovered supernova remnant in Cygnus (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 222
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 21
    facet.materialart.
    Unknown
    2.8 and 6 cm wavelength observations of NGC 7822 (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 61; 2, Oc; Oct. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 22
    facet.materialart.
    Unknown
    V 701 Scorpii and its place among early contact binaries (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 61; 1, Oc; Oct. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 23
    facet.materialart.
    Unknown
    Structure of radio sources with remarkably flat spectra - PKS 0735+178 (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Three incoherent synchrotron models are used to account for the very flat radio spectrum of the BL Lac object PKS 0735+178. The first interpretation is that the spectrum results from optically-thin synchrotron emission from relativistic electrons with a particular energy distribution. The second posits a single nonuniform, self-absorbed source generated by a wind flowing from a central object. The third suggests that sources with flat spectra are caused by the presence of multiple (three or more) discrete uniform components, and that the magnetic field and relativistic electron distribution for each source is correlated with the size of the individual components. It is proposed that the last model is the most tenable explanation of the phenomenon, and multi-frequency VLBI observations are suggested for the evaluation of the detailed structure of compact radio sources.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 82; Oct. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 24
    facet.materialart.
    Unknown
    Search for microarcsecond structure in low-frequency variable radio sources (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A search for interstellar scintillation (ISS) of low-frequency variable radio sources is reported. Observations of 28 confirmed or suspected low-frequency variables, 21 nonvariable sources, and two pulsars were made at 408 MHz. As expected, the pulsars showed ISS, but scintillation was not detected in any other source. A typical upper limit to the rms modulation due to ISS is 150 mJy, giving lower limits to the apparent angular diameter of about 10 to the -6th arcsec. The possibilities that a true point source is broadened to an apparent angular diameter greater than or roughly equal to 10 to the -6th arcsec by scattering local to the source or in a general intergalactic medium are discussed.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 82; Oct. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 25
    facet.materialart.
    Unknown
    Extragalactic sources with strong millimeter-wave emission (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Observations at 90 GHz of a sample of 38 sources chosen to have flat or rising spectra between 0.318 and 5 GHz are reported. Roughly 25% of the sources were found to have flat or rising spectra between 5 and 90 GHz. The optical magnitude of each of the sources from the E print of the Palomar Sky Survey has also been estimated. Evidence is found for a correlation between the 90-GHz flux density and the optical magnitude, suggesting a relationship between the emission processes at these frequencies. Little evidence is found for a correlation between the low- and high-frequency spectral indices of the sources. This suggests that the sources tend to be opaque at centimeter wavelengths and optically thin at millimeter wavelengths. The properties of two of the more interesting sources are also discussed. Evidence is presented that strong millimeter activity may be generally associated with the BL Lac phenomenon.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 82; Oct. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 26
    facet.materialart.
    Unknown
    Gamma ray spectroscopy in astrophysics: An observational overview (50 keV-20 MeV) (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The observational status of gamma ray astronomy based on results reported prior to April 1978 is discussed. Specific line observations are reviewed from the Sun, the galactic plane, the Galactic Center region, the active Galaxy NGC 5128 (Cen A), the Crab Nebula region, and a transient source in the general direction of the anti-Galactic Center region. A statistical method is described which determines the relative probability that a given, reported observation is due to an external source as compared to a random fluctuation in the experimental background counting rate. Only a few of the many reported observations can be considered likely extraterrestrial observations of an extraterrestrial source made with a confidence level of 99%.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center Gamma Ray Spectry. in Astrophys.; p 42-68
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 27
    facet.materialart.
    Unknown
    Supernovae, grains and the formation of the solar system (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: An investigation is conducted concerning the possibility that observed Mg-26 anomalies in meteorites may be related to a nucleosynthetic event which preceded the formation of the solar system by at most a few million years. The Al-26, which decayed to form the observed excess Mg-26, could have been produced in either explosive carbon burning or in a high temperature carbon burning shell source immediately preceding the explosion. The results of supernova grain condensation calculations are presented and related to the hypothesis that a 'last event' supernova was indeed related to the formation of the solar system and thus might have created the observed isotopic anomalies in magnesium, oxygen, neon, and xenon.
    Keywords: ASTROPHYSICS
    Type: Nature; 269; Sept. 8
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 28
    facet.materialart.
    Unknown
    The composition of comets (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Questions concerning the origin of comets are considered. It is pointed out that the molecular composition of a dense interstellar cloud appears to have exactly the composition needed to produce the observed features of the visible cometary spectrum, which consists mainly of emission bands of unstable free radicals. A working model of cometary structure is discussed together with the classical observations which have led to it. The discussed model was originally described by Whipple (1951). It is emphasized that the model can serve only as a rough guide in efforts to interpret the evolution of cometary behavior. A survey is provided of new techniques which have only recently been applied to cometary observations, taking into account the spectrum of a comet, radio observations, and ultraviolet observations.
    Keywords: ASTROPHYSICS
    Type: American Scientist; 65; May-June
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 29
    facet.materialart.
    Unknown
    Nonradial pulsational instability of massive stars (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Pulsational eigenfrequencies and stability coefficients of the lowest modes of nonradial quadrupole (l = 2) oscillation have been obtained for chemically homogeneous stellar models constructed with Carson's (1976) radiative opacities. Instability is found to develop as a result of the same operation of the kappa-mechanism in the CNO ionization zone and at nearly the same stellar masses as was the case for the radial (l = 0) modes studied previously. A survey of the l = 5 modes indicates that the instability gradually declines with increasing degree of the spherical harmonics.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 214
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 30
    facet.materialart.
    Unknown
    Galactic distribution of X-ray burst sources (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Data on X-ray bursts recorded by the OSO-8 and SAS-3 satellites and criteria (rise time, duration, recurrence) for X-ray bursts are examined in a study of possible correlation between the galactic longitude distribution of X-ray burst sources and globular clusters. Correlations are weak, with only two X-ray bursts sources (NGC6624 and the rapid burster) coinciding with globular clusters, another seven possibly coinciding, most not correlated. Ad hoc explanations (globular clusters obscured by dust clouds, bursts associated with remnants of disrupted globular clusters evolved into supermassive black holes) are considered briefly.
    Keywords: ASTROPHYSICS
    Type: Nature; 267; May 5
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 31
    facet.materialart.
    Unknown
    The continuous UV flux of Alpha Lyrae - Non-LTE results (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Non-LTE calculations for the ultraviolet C I and Si I continuous opacity show that LTE results overestimate the importance of these sources of opacity and underestimate the emergent flux in Alpha Lyr. The largest errors occur between 1100 and 1160 A, where the predicted flux in non-LTE is as much as 50 times larger than in LTE, in reasonable accord with Copernicus observations. The discrepancy between LTE models and observations has been interpreted to result from the existence of a chromosphere. Until a self-consistent non-LTE model atmosphere becomes available, such an interpretation is premature.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 214
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 32
    facet.materialart.
    Unknown
    Submillisecond measurements of the low state of Cygnus X-1 (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Cygnus X-1 was observed on two occasions separated by a year by the same Goddard X-ray rocket payload. High-resolution temporal and spectral data reveal that Cyg X-1 was essentially unchanged in these two observations a year apart; the bursts of millisecond duration observed in the earlier flight were observed in the second as well. Analysis of these bursts has failed to reveal any internal temporal structure, either luminous or spectral. The shot-noise character of temporal fluctuations on time scales of at least 1 s can be explained by the presence of exponential pulses with a time constant of a fraction of a second and a rate near 8 per sec. The possible connection of these pulses with the bursts is examined.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 213
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 33
    facet.materialart.
    Unknown
    On the rapid variability of central stars of planetary nebulae (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Envelope models for central stars of planetary nebulae have been constructed with Carson's (1976) radiative opacities. A stability analysis of these envelopes indicates that for a sufficiently high luminosity, the fundamental mode of radial pulsation is excited by the kappa mechanism operating in the CNO ionization zone. At somewhat higher luminosities the lowest overtones also become unstable. This may possibly explain the rapid variability that is observed in some central stars, if the time scale of the variations is minutes to hours.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 213
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 34
    facet.materialart.
    Unknown
    Accretion torques in X-ray pulsars (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: An analysis of the accretion process in an X-ray pulsar, whereby angular momentum is transferred to the star and its rotation period is changed, is presented, and an expression for the fractional rate of change of the pulse period in terms of X-ray luminosity and other star parameters is derived. It is shown that observed characteristic spin-up time scales for seven X-ray pulsars strongly support the view that in every source (1) the pulse period reflects the rotation period of a compact object, (2) the accretion is mediated by a disk surrounding the compact object and rotating in the same sense, and (3) the compact object is a neutron star rather than a white dwarf.
    Keywords: ASTROPHYSICS
    Type: Nature; 266; Apr. 21
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 35
    facet.materialart.
    Unknown
    Observations of the unidentified 3.3 micron emission feature in nebulae (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Spectrophotometric observations from 2.1 to 4.1 microns of a variety of objects exhibiting the 3.3-micron emission feature (first detected in NGC 7027) are reported. The characteristics of the feature, the various environments in which it is found, and possible emission mechanisms are discussed in light of all the available observations of the feature to date. A resonance feature in solids is the most probable emission mechanism; however, no satisfactory identification has yet been made on the basis of infrared spectroscopy of terrestrial materials.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 213
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 36
    facet.materialart.
    Unknown
    Spectrum of the Kleinmann-Low nebula from 29 to 125 micrometers (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The infrared spectrum of the Kleinmann-Low nebula in M42 has been measured from 80 to 350 kaysers (approximately 29 to 125 microns) with a Michelson interferometer aboard the NASA Kuiper Airborne Observatory. The frequency spectrum peaks at about 185 kaysers. A simple model of the emission implies that the temperature is in the range 70-95 K and that the optical depth is at least 0.2 at the peak frequency. A possible absorption is seen at about 176 kaysers. Thermal emission by dust at a temperature of 71 K, with the absorption cross section proportional to frequency, provides a good fit to the data. Other thermal-emission models can also fit the spectrum. The data are compared with previous broad-band measurements. Upper limits are placed on expected line emission from the surrounding H II region at the position of the nebula.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 37
    facet.materialart.
    Unknown
    The supernova trigger for formation of the solar system (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: It is suggested that the explosion of a Type II supernova triggered the collapse of a nearby interstellar cloud and led to the formation of the solar system. Estimates of the abundances resulting from nuclear processing of the supernova ejecta are presented. It appears promising that nucleosynthesis in this single supernova event can account for most isotopic anomalies and traces of extinct radioactivities in solar-system material.
    Keywords: ASTROPHYSICS
    Type: Icarus; 30; Mar. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 38
    facet.materialart.
    Unknown
    Binary X-ray pulsars (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Recent progress in the study of the pulse profiles of the nine known binary X-ray pulsars is discussed. The sources considered include SMC X-1, Her X-1, Cen X-3, A0535+26, GX1+4, 3U 0900-40, A1118-61, GX301-2, and 3U 0352+30. Sample X-ray profiles for these sources are provided, and general features exhibited by the profiles are identified. It is noted that the apparent existence of a gap in the period distribution of X-ray pulsars, in the range from about 5 to 100 sec, seems to be genuine within obvious statistical limitations and is probably not an observational effect. Two explanations for the production of X-ray pulsations are examined: one requiring a temporal modulation of mass accretion onto the surface of a neutron star and another requiring the funnelling of matter along magnetic field lines to the neutron star's surface.
    Keywords: ASTROPHYSICS
    Type: Nature; 266; Mar. 10
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 39
    facet.materialart.
    Unknown
    Numerical solution for subcritical flows by a transonic integral equation method (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The method presented makes use of a division of the region of integration into closed rectangular elements. The velocity is taken to be constant in each element. The integral equation is reduced to a matrix equation which can be solved by an appropriate iteration approach. The derivation and solution of the matrix equation are discussed and the matrix elements are considered. The described concepts were implemented for a nonlifting parabolic-arc airfoil.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 15; Mar. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 40
    facet.materialart.
    Unknown
    Spectrographic observations of comet West /1975 n/ (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The spectrum of comet West (1975 n) was recorded on March 7 and 11, 1976, in the wavelength interval from 5700 to 8200 A at an intermediate resolution. One hundred twenty-two emission lines are reported, with 78 lines having identifications with spectral features of NH2, H2O(+), C2, O I forbidden emission, and Na I.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific; vol. 89
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 41
    facet.materialart.
    Unknown
    Hydrostatic equilibrium of gas, extent of cosmic ray confinement, and radio emission in the Galaxy (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A detailed study of the hydrostatic equilibrium of the gas-field system perpendicular to the galactic plane in the neighborhood of the sun, assuming that the magnetic field is parallel to the plane, has been carried out. It is found that the distribution of pressure due to cosmic rays and the magnetic field is different from that due to the gas. The observed radio spectrum in the direction of the galactic pole can be understood if one includes in the hydrostatic equilibrium the distribution of gas in the halo. The results of this analysis show that in the galactic plane, the cosmic-ray density is approximately 2 to 3 eV/cu cm with a magnetic-field strength of about 5 to 6 microgauss. It is inferred that cosmic rays are confined to a more extended volume in the Galaxy (with an equivalent thickness of at least 2 kpc in the solar neighborhood) than the gas disk, and the magnetic-field strength slowly decreases to a value of 1 microgauss only beyond about 5 kpc from the plane. Further, there is no evidence for a quasi-spherical radio halo, although the radio emission extends beyond the gas disk with scale height of at least 1 kpc. A lower limit of about 6 million years for the confinement of cosmic rays in the Galaxy has been set.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 42
    facet.materialart.
    Unknown
    The black tide model of QSOs (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The paper develops certain aspects of a model wherein a QSO is a massive black hole located in a dense galactic nucleus, with its growth and luminosity fueled by tidal disruption of passing stars. Cross sections for tidal disruptions are calculated, taking into account the thermal energy of stars, relativistic effects, and partial disruption removing only the outer layers of a star. Accretion rates are computed for a realistic distribution of stellar masses and evolutionary phases, the effect of the black hole on the cluster distribution is examined, and the red-giant disruption rate is evaluated for hole mass of at least 300 million solar masses, the cutoff of disruption of main-sequence stars. The results show that this black-tide model can explain QSO luminosities of at least 1 trillion suns if the black hole remains almost maximally Kerr as it grows above 100 million solar masses and if 'loss-cone' depletion of the number of stars in disruptive orbits is unimportant.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 43
    facet.materialart.
    Unknown
    Isotopic abundance of CO in interstellar clouds (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The fractional abundances of the isotopic species of carbon monoxide in interstellar clouds are calculated on a basis of gas-phase ion-molecule reactions. The (C-13)O/(C-12)O ratio varies significantly with extinction of the ultraviolet radiation field, and in the outer regions of dark dense clouds (C-13)O may be enhanced by a factor of 10. The observational interpretation of the CO to H2 or interstellar-reddening relation and the isotopic abundances of carbon are complicated by these effects.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 44
    facet.materialart.
    Unknown
    The hard X-ray pulse profile of the transient source A0535+26 (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Measurements of the 104 sec pulse profile of A0535+26 at energies near 50 keV are reported. The data were obtained with a balloon-borne detector system which was launched on May 22, 1975 with the objective to observe transient or periodic emissions from X-ray or gamma-ray sources. The presence of the source was detected by a superposed epoch analysis. The pulse profile of A0535+26 in two energy channels is presented in a graph.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 45
    facet.materialart.
    Unknown
    All-Sky Monitor observations of the decay of A0620-00 /Nova Monocerotis 1975/ (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The All-Sky X-ray Monitor on board Ariel-5 has observed the 3-6 keV decline of the bright transient X-ray source A0620-00 on a virtually continuous basis during the period 1975 September-1976 March. The source behavior on time scales greater than about 100 minutes is characterized by smooth, exponential decays interrupted by substantial increases in October and February. The latter increase was an order-of-magnitude rise above the extrapolated exponential falloff, and was followed by a final rapid decline below a level of about 0.05 per sq cm per sec by late March. Upper limits of 2.5% and 10% were found for any periodicities in the range 0.2-10 days during the early and later decay phases, respectively. A probable correlation between the optical and 3-6 keV emission from A0620-00 has been noted, effectively ruling out models involving traditional optical novae in favor of Roche-lobe overflow in a binary system. The existing data on the transient X-ray sources are consistent with two distinct luminosity-lifetime classes of these objects.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 46
    facet.materialart.
    Unknown
    Orbital changes of the gaseous ring around Be stars (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: In order to understand the seemingly erratic V/R variations and radial velocity curves of emission edges and central absorption of some Be stars, we have advanced, for the changes of structure of the gaseous ring around these stars, a theory that is based on the interaction between the existing ring and the newly ejected matter from the star. It shows that the structural change of the ring is completely controlled by the angular-momentum input factor and the dissipation factor. In light of this understanding, we have gone on to interpret the observed results of Beta-1 Mon and Pi Aqr.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 212
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 47
    facet.materialart.
    Unknown
    Recurrent X-ray outbursts from Aquila X-1 (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Ariel V All-Sky Monitor observations of Aql X-1 are reported and compared with previous observations that indicate the existence of 'low' and 'high' intensity states. All the data considered are shown to be consistent with flaring episodes having a mean flare interval of 435 days with an rms scatter of about 10%. It is suggested that the observations are most easily interpreted in terms of an 'X-ray dwarf nova' binary of the type proposed for the transient X-ray source A0620-00. Constraints on more detailed features of the source model are discussed.
    Keywords: ASTROPHYSICS
    Type: Nature; 265; Feb. 17
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 48
    facet.materialart.
    Unknown
    On the relationship of interstellar N2H/+/, HCO/+/, HCN, and CN (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A survey of 73 sources has been made in the emission lines of N2H(+) and HCO(+), including detailed maps of four sources (Ori A, OMC-2, DR 21 OH, and NGC 6334). These data are combined with equally extensive data for HCN and CN to make a detailed study of the spatial relationship of these four species. Actual abundance ratios are shown to vary, often sharply, over small scale lengths (of the order of 1 arcmin) within the mapped sources. Excitation temperatures also vary. All four species appear to be subthermally excited. The abundance ratios and their spatial variations are interpreted in terms of ion-molecular formation and destruction processes. It is concluded that the relative abundances of CO may be considerably lower in some regions than previously believed. No evidence is found for variations in the C/O ratio over small scale lengths in Ori A. The degree of ionization of the Ori A molecular cloud may be significantly different from that of other molecular clouds.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 211
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 49
    facet.materialart.
    Unknown
    Derivation of an integral equation for transonic flows (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: It is noted that the nonlinear partial differential equation for the perturbation velocity potential and boundary conditions describing steady inviscid compressible transonic flow past a thin two-dimensional airfoil can be transformed into a singular integrodifferential equation and that differentiation of the latter yields an integral equation. Two forms of this integral equation currently exist: one for the singularity that is enclosed in an infinitely long strip of vanishing thickness and the other for the singularity that is enclosed in a vanishing circle. In the present article, a more general integral equation is derived by enclosing the singularity in a vanishing rectangular cavity of arbitrary aspect ratio. The two existing forms of this equation are deduced as special cases distinguished by the respective values for the aspect ratio (infinity for the first form and unity for the second).
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 15; Feb. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 50
    facet.materialart.
    Unknown
    A simple physical model for X-ray burst sources (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: In connection with information considered by Illarianov and Sunyaev (1975) and van den Heuvel (1975), a simple physical model for an X-ray burst source in the galactic disk is proposed. The model includes an unevolved OB star with a relatively weak stellar wind and a compact object in a close binary system. For some reason, the stellar wind from the OB star is unable to accrete steadily on to the compact object. When the stellar wind is sufficiently weak, the compact object accretes irregularly, leading to X-ray bursts.
    Keywords: ASTROPHYSICS
    Type: Nature; 265; Jan. 20
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 51
    facet.materialart.
    Unknown
    Aerodynamic effects (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The tethered satellite concept provides an ideal platform for the study of the interaction of the atmosphere with satellites of various shapes and surfaces under a wide range of flow conditions. From experiments which would measure the drag, lift, and torque acting on the tethered satellite, important information could be obtained which would have application to satellite lifetime prediction, determination of properties of the upper atmosphere, and scientific information on the interaction of high speed molecules with surfaces (the gas surface interaction). These experiments using the tethered satellite concept are described and would measure the following variables: angle of attack, surface roughness, and flow properties.
    Keywords: AERODYNAMICS
    Type: UAH(NASA Workshop on the Use of a Tethered Satellite System; p 151-155
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 52
    facet.materialart.
    Unknown
    Flow characteristics in an expansion tunnel as inferred from velocity measurements (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A photoionization technique was used to study flow characteristics in an expansion tunnel. Vertical surveys of the axial component of flow velocity just downstream from the nozzle exit were obtained, and estimates of freestream density were inferred from the velocity measurement technique. The pitot pressure was measured and compared to the average axial component of velocity as a function of time for the two cases when air and CO2 were used as test gases. Vertical velocity and static density profiles at the nozzle exit are presented for the case when CO2 was used as test gas. Experimental results were used to determine the diameter and uniformity of the test core at the nozzle exit and the duration of the quasi-steady flow period. These data are relevant to evaluation of the suitability of operating an expansion tube as an expansion tunnel. The expansion tunnel is an expansion tube with a conical nozzle positioned at the exit of the acceleration section, so that nozzle entrance flow conditions are hypersonic and characterized by hypervelocity.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 15; Sept
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 53
    facet.materialart.
    Unknown
    Interplanetary current sheets at 1 AU (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The structure and nature of 'discontinuities' in the interplanetary magnetic field at 1 AU in the period from March 18 to April 9, 1971, is determined by using high-resolution magnetic-field measurements from Explorer 43. The discontinuities that were selected for this analysis occurred under a variety of interplanetary conditions at an average rate of 0.5/hour. Both tangential and rotational discontinuities were identified. Tangential discontinuities were observed every day, even among Alfvenic fluctuations. In particular, on one day during which Alfvenic fluctuations were intense and persistent in a high-speed stream, tangential discontinuities (TD's) were seen throughout the day at an average rate of 0.5/hour; rotational discontinuities (RD's) were also observed during this day at a higher than usual rate, the ratio of TD's to RD's being approximately one. The structure of most of the current sheets was simple and ordered; i.e., the magnetic field usually changed smoothly and monotonically from one side of the current sheet to the other. The thickness distributions of the TD's and RD's with very smooth current sheets were similar. The average thickness of the RD's was 1200 km (13 proton Larmor radii), and the average thickness of the TD's was 1300 km (12 proton Larmor radii).
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research; 82; Aug. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 54
    facet.materialart.
    Unknown
    Mass loss, long-period variables, and the formation of circumnebular shells (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: We have found that the rate of mass loss M increases with an increase in the period of pulsation for Mira-type variables. This result suggests that the rate of mass loss is accelerated with time until a maximum value is reached before the ejection of the outer envelope. The matter from the continuous mass loss during the evolution of the star produces supersonic shock waves that sweep up the interstellar gas upon encountering the interstellar medium, so that a shell is formed. This phenomenon may account for the observations of extended regions of emission that surround planetary nebulae.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 216
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 55
    facet.materialart.
    Unknown
    Evidence for mass loss in the mid-ultraviolet spectra of Be stars (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The spectral region about the Mg II doublet lines near 2800 A of Be and shell stars has been observed. The star Gamma Cas shows narrow components to each resonance doublet line shifted 215 km/s toward shorter wavelengths. The resonance and subordinate lines of Zeta Tau are shifted toward shorter wavelengths by 75 km/s, and the subordinate lines are greatly strengthened. The star Kappa Dra, which is much later in spectral type, shows a comparatively normal doublet spectrum.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 216
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 56
    facet.materialart.
    Unknown
    Scale-covariant theory of gravitation and astrophysical applications (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Generalized Einstein equations invariant under scale transformations are presented, and several astrophysical tests studied. It is assumed that the dynamics of atoms or clocks used as measuring apparatus is given a priori. Connection with gauge fields and broken symmetries is made through the cosmological constant.
    Keywords: ASTROPHYSICS
    Type: Physical Review Letters; 39; Aug. 22
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 57
    facet.materialart.
    Unknown
    What is a cometary nucleus (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The meaning of the term 'cometary nucleus' is discussed, taking into account observations of comets with different characteristics. It is pointed out that for some comets, there may be no nucleus to be seen at any time, while in others as the comet brightens or undergoes changes, a nucleus may develop to be seen for a time or even intermittently, while occasionally more than one nucleus may be seen to be present. On the basis of a study of observational reports it emerges that no more than about 30 per cent of comets exhibit anything resembling a starlike nucleus.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 18
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 58
    facet.materialart.
    Unknown
    Statistical equilibrium in cometary C2. I (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Swan-band emission from the C2 molecule provides important information for a study of the physical processes occurring in comets. It is, therefore, a disturbing factor that many quantitative Swan-band observations are in clear contradiction of predictions of resonance fluorescence excitation of the Swan bands. A description is presented of an investigation involving an application of resonance fluorescence theory to C2. The investigation takes into account all important electronic transitions which determine the population distribution of the lowest energy states. It is found that the previous discrepancy for the brighter band sequences disappears.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 216
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 59
    facet.materialart.
    Unknown
    Evolution of helium stars (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The evolution of helium stars in the mass range from 4 to 15 solar masses has been followed from the initial helium main sequence to the end of carbon burning in the core, with the use of Carson's (1976) radiative opacities. As compared with earlier work based on smaller opacities, the main-sequence band in the H-R diagram is now both wider and cooler than before. If neutrino losses are neglected in the stellar models, the phase of carbon burning in the core occurs in the red-supergiant region; otherwise, it occurs, as it does in the earlier models with or without neutrino emission, close to the helium main sequence. Observational data for Wolf-Rayet stars and R Coronae Borealis variables are found to lend some support to the present models.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 216
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 60
    facet.materialart.
    Unknown
    Low Reynolds number flow past a blunt axisymmetric body at angle of attack (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Low Reynolds number flow of an ideal gas over a blunt axisymmetric body of large half-angle at small angles of attack is investigated, for the case of laminar hypersonic flow. Time-varying viscous shock layer equations describing the flowfield are obtained from the full Navier-Stokes system by keeping terms to second order in the inverse square root of Re in both viscous and inviscid regions; the equations are valid for moderate to high Re. Drag, skin friction, and heating rates were obtained at small (or zero) angles of attack. Conditions experienced by planetary entry probes during the high-altitude (early) legs of an atmospheric entry trajectory are pertinent to the problem.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 15; Aug. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 61
    facet.materialart.
    Unknown
    Optical, infrared and radio studies of compact H II regions. II - The H alpha knot S88B (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 59; 2, Ju; July 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 62
    facet.materialart.
    Unknown
    Lyman-alpha observations of Comet West /1975n/ (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The rate of hydrogen production of Comet West is studied through rocket observation of solar Lyman-alpha radiation resonantly scattered by the escaping hydrogen atoms. Two sets of Lyman-alpha exposure sequences are used to obtain computer-smoothed brightness contour (isophote) maps covering a density range of 100:1. A simple radial outflow model is applied to the contour maps to determine the rate of hydrogen production (3.2 by 10 to the 30th power atoms/sec.) Discrepancies between the observed shape of the outer isophotes and predicted models may be explained by optical depth effects, or by the presence of small pieces of the comet's nucleus distributed along the orbit. Hydrogen, carbon, and oxygen production for Comet West and Comet Kohoutek are compared; differences may be accounted for by variations in the composition or evolution of the two comets.
    Keywords: ASTROPHYSICS
    Type: Icarus; 31; Aug. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 63
    facet.materialart.
    Unknown
    Interstellar clouds and molecular hydrogen (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Data obtained from the Copernicus Orbiting Astronomical Observatory, launched in 1972 and still obtaining information, are used in a discussion of the interstellar medium. The Copernicus instruments have facilitated direct estimates for the density and temperature of individual interstellar clouds, and improved the ability to determine where along the line of sight a cloud lies with respect to background stars. The physical characteristics of hydrogen molecules are considered, with attention to the formation and destruction of interstellar hydrogen. The differences between 'thin' clouds, in which molecular hydrogen is optically thin, and 'thick' clouds are examined. Several features of the interstellar medium are described.
    Keywords: ASTROPHYSICS
    Type: American Scientist; 65; July-Aug
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 64
    facet.materialart.
    Unknown
    Positions of X-ray sources near the galactic center measured by the Ariel-5 RMC experiment (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 215
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 65
    facet.materialart.
    Unknown
    Spectroscopic studies of very old hot stars. III - Atmospheric properties of seven planetary nuclei (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The atmospheric properties of seven planetary nuclei which have O or Of-type spectra were determined by use of the Zanstra method and by analysis of the visual line spectra. One finding is that the O-type spectral sequence may extend to effective temperatures of 90,000 kelvins or more, if the results of the Zanstra method are to be believed. However, there are some indications of internal inconsistency in the Zanstra method and some outstanding discrepancies between the effective temperatures indicated by the Zanstra method and those indicated from analysis of the visual line spectra. Two ways to resolve these discrepancies are to postulate an excess of extreme-UV stellar flux or to postulate a hot binary companion for some central stars. In either case the validity of the Harmon-Seaton evolutionary sequence for central stars becomes questionable.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 215
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 66
    facet.materialart.
    Unknown
    The relationship between the galactic matter distribution, cosmic-ray dynamics, and gamma-ray production (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The concept that cosmic-ray density is related to the matter to which cosmic rays are dynamically coupled through magnetic fields on the scale of galactic arm segments is considered with specific reference to gamma-ray astronomy. A model of the galactic-matter and cosmic-ray distributions is developed on the basis of 21-cm radio surveys and recent observations of the 2.6-mm CO emission line by assuming that cosmic rays are galactic in origin, their column density is proportional to the total interstellar-gas column density, their scale height is considerably larger than that of the matter, and the Galaxy is a spiral with an arm/interarm density ratio of about 3 to 1. It is found that there is a good correlation between the observed gamma-ray intensity and that predicted on the basis of essentially complete coupling of cosmic rays to the best estimate of atomic and molecular hydrogen in the Galaxy. Individual maxima observed in gamma-radiation from the central region of the Galaxy are shown to be well correlated with those predicted to result from certain spiral-arm tangents if all the matter is assumed to be modulated in a particular spiral-arm segment pattern.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 215
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 67
    facet.materialart.
    Unknown
    Evaluation of flight spoilers for vortex alleviation (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The paper describes the facilities and test procedures used in a series of wind-tunnel and full-scale flight investigations of the effectiveness of flight spoilers currently existing on wide-bodied transport jet aircraft when used as trailing vortex hazard alleviation devices. Examples of the results of such studies include the variation of trailing wing rolling-moment coefficient with downstream distance behind a B-747 airplane model with various segments of its flight spoilers deflected 45 deg, and comparisons with models without spoilers deflected. It is concluded that the existing flight spoilers on the B-747 are effective as trailing vortex attenuators.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 14; Aug. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 68
    facet.materialart.
    Unknown
    The effect of ablation injection on radiative and convective heating (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A viscous shock-layer analysis for calculating high energy equilibrium flow fields about blunt axisymmetric bodies is applied to the problem of massive ablation injection with radiation transport. A nongray radiation model is used that accounts for both line and continuum radiation. The solution method is direct and provides both stagnation and downstream solutions. Results for shock heated air show that phenolic-nylon injection is substantially more effective in reducing the wall radiant flux than air injection. Also, for large included body angles, the wall radiative flux and the coupled phenolic-nylon injection rate do not continue to decrease with increasing distance downstream.
    Keywords: AERODYNAMICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 69
    facet.materialart.
    Unknown
    X-ray spectra of Hercules X-1. I - Iron line fluorescence from a subrelativistic shell (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The X-ray spectrum of Her X-1 was observed in the energy range from 2 to 24 keV from August 29 to September 3, 1975. Emission features are observed near the K-alpha iron-line energy which exhibit both broadening and a double line structure. The total luminosity in these features is about 4 by 10 to the 35th power ergs/s. Iron line fluorescence from an opaque cool (not exceeding 1 million K) shell of material at the Alfven surface provides the necessary luminosity in this feature. The double line structure and the line energy width can be due to Doppler shifts if the shell is forced to corotate with the pulsar at a radius of at least 800 million cm. Implications of this model regarding physical conditions near Her X-1 are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 215
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 70
    facet.materialart.
    Unknown
    The origin of the broad line emission from Seyfert galaxies (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Mass loss from an accretion disk around a supermassive (of the order of 100 million solar masses) black hole is proposed as the origin of the broad permitted lines of Seyfert galaxies and QSOs. The material is expelled by ionizing radiation emitted near the center of the disk and striking it at a radius of approximately 10 to the 16.5 power cm. The escaping gas initially has a density of about 1 trillion per cu cm, high enough for radiation pressure to accelerate the gas to high radial velocities. The model leads to line emission from tiny dense filaments moving at about 10,000 km/s in a region roughly 10 to the 17th power cm across. This agrees with the observed broad line widths, variability time scales, and the absence of broad forbidden-line emission.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Letters; 18; 3, 19; 1977
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 71
    facet.materialart.
    Unknown
    Comment on 'Drag coefficient of spheres in continuum and rarefied flows' (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A paper by Henderson (1976) provides a method of predicting experimental sphere drag data. This approach uses two equations for the drag coefficient, one for relative Mach number less than one, one for relative Mach number greater than 1.75. For relative Mach numbers between these limits a linear interpolation procedure is followed. In a comment on this paper, it is claimed, on the basis of comparing predictions with experimental results, that a method proposed by Walsh (1975) gives better predictions of the drag coefficient for relative Mach numbers less than 1.75, provided that a modification of the procedure is made for relative Mach numbers less than 0.1. For values over 1.75, both methods are considered equally accurate. In a reply to this comment, it is agreed that the Walsh method is more accurate when Reynolds numbers are within a range between 20 and 200, and Mach numbers are between 0.5 and 1.25. Presumed errors and possible limitations in the Walsh procedure for predicting drag coefficients are discussed.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 15; June 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 72
    facet.materialart.
    Unknown
    Transient structure in the high-energy X-ray light curve of NP 0532 (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The paper reports the observation of pulsed fractions in the primary and secondary peaks, as well as in the interpulse region, of the high-energy X-ray light curve of NP 0532. A statistical analysis of light-curve data is performed, and a similar analysis is carried out using simulated data. It is concluded that a previously reported third peak in the light curve was transient in nature.
    Keywords: ASTROPHYSICS
    Type: Nature; 266; Mar. 31
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 73
    facet.materialart.
    Unknown
    Dirac cosmology (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The large numbers hypothesis (LNH) linking the magnitude of large dimensionless ratios in physics (on the order of 10 to the 40th power) to cosmic time is examined. The LNH is checked against evidence on 3K background radiation of the universe and the (log N, log S)-relation for radio galaxies. Earlier criticisms of LNH by Gamow and Teller are examined, and alternative hypotheses put forth by Dicke and Carter (1974) are discussed. The discussion covers: continuous (additive or multiplicative) creation of matter, the Einstein metric and the atomic metric, and general cosmological and local astronomical implications of LNH. LNH is also viewed in relation to solar evolution and pulsar physics.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 211; Jan. 15
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 74
    facet.materialart.
    Unknown
    Vortex lattice prediction of subsonic aerodynamics of hypersonic vehicle concepts (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The vortex lattice method introduced by Lamar and Gloss (1975) was applied to the prediction of subsonic aerodynamic characteristics of hypersonic body-wing configurations. The reliability of the method was assessed through comparison of the calculated and observed aerodynamic performances of two National Hypersonic Flight Research Facility craft at Mach 0.2. The investigation indicated that a vortex lattice model involving 120 or more panel elements can give good results for the lift and induced drag coefficients of the craft, as well as for the pitching moment at angles of attack below 10 to 15 deg. Automated processes for calculating the local slopes of mean-camber surfaces may also render the method suitable for use in preliminary design phases.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 14; Oct. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 75
    facet.materialart.
    Unknown
    Cooling effectiveness of slot injection into a turbulent boundary layer (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The cooling effectiveness of injection through multiple flush slots at an angle of 10 deg was studied experimentally in a wind tunnel. Air was injected from one to four slots into a turbulent Mach 6 boundary layer. The slot mass flow ratio is defined, and data which describe the dependence of the cooling effectiveness on the slot mass flow ratio are presented. Experimental values are indicated graphically for various cases of single and multiple slot injection, where the total mass injection (i.e., the sum of flow rates from each slot) is the same for each case. The results show that, for a given coolant mass flow rate, thermal protection over the maximum surface area can be accomplished best by injecting the coolant flow through multiple slots.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 15; Sept
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 76
    facet.materialart.
    Unknown
    Intensity transitions in Cyg XR-1 observed at high energies from OSO 8 (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The observed transitions at energies above 20 keV show that the spectrum of Cyg XR-1 exhibits the pivoting effect during intensity transitions expected from two-temperature accretion disk models of the X-ray emitting region. Cyg XR-1 was observed with the high-energy X-ray spectrometer on board the OSO-8 satellite from November 11-19, 1975 and from October 27 to November 15, 1976 (excluding the period from November 1 to November 7, 1976).
    Keywords: ASTROPHYSICS
    Type: Nature; 267; June 30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 77
    facet.materialart.
    Unknown
    On the accretion disk model of QSOs (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The accretion-disk model for the optical continuum of QSOs has been investigated using the standard viscous-stress ('alpha-P') formalism. It is found that with a maximum allowable mass of 10 billion solar masses, the standard model with sub-Eddington flow falls a factor of 10 short of the luminosity of the brightest QSOs. Models with the higher mass-flow rates required to reach the maximum luminosities produce most of their energy in an optically thin region which has not yet been self-consistently treated. The disk model with sub-Eddington flow has difficulty in producing a power law of the correct slope over the optical band. It is suggested that nonthermal processes may be needed to explain the optical properties of QSOs.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 59; 1, Ju; July 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 78
    facet.materialart.
    Unknown
    Radiative acceleration of gas above a luminous disk (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Radiative acceleration as a mechanism for ejection of matter from quasistellar objects is considered, and calculations are presented showing that a strongly beamed outflow will result if the source of the driving radiation is a disk. The net forces exerted by an infinitesimally thin, optically thick disk emitting thermal radiation with given intensity on clouds or particles is calculated, and conditions for beaming are obtained. Apparently it is possible to establish strong beaming within a distance of the order of the disk radius.
    Keywords: ASTROPHYSICS
    Type: Nature; 266; Apr. 21
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 79
    facet.materialart.
    Unknown
    The chemical composition of three planetary nebulae in the Magellanic Clouds (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The paper studies the detailed spectral characteristics of the planetary nebulae N97 and N153 in the Large Magellanic Cloud (LMC), the planetary nebula N67 in the Small Magellanic Cloud (SMC), and the small H II regions N9, N61, and N81 in the SMC. Electron temperatures and densities for each nebula are derived from emission-line strengths determined by photographic spectrophotometry, and relative abundances are estimated for H, He, N, O, Ne, Ar, and S. The results show that: (1) N67 has a 60% overabundance in He/H while N97 and N153 have approximately normal He/H values; (2) all three planetaries have N/H values comparable to those of galactic planetaries but substantially higher than found in the H II regions of their respective Cloud; (3) the O/H values in the planetaries are similar to or lower than those in the H II regions of the respective Cloud; (4) the O/Ne, O/S, and O/Ar ratios in the two LMC planetaries are comparable to those in galactic planetaries; (5) the compositions of the small H II regions in the SMC are nearly identical to those of previously studied large H II regions in the same Cloud; and (6) the He/H ratio of the interstellar gas in the SMC is about 25% less than that in the Galaxy. It is concluded that most of the N abundance in both Clouds arose from nucleosynthesis sources other than planetary nebulae.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 211; Jan. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 80
    facet.materialart.
    Unknown
    Gamma rays and the case for baryon symmetric big-bang cosmology (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The baryon symmetric big-bang cosmologies offer an explanation of the present photon-baryon ratio in the universe, the best present explanation of the diffuse gamma-ray background spectrum in the 1 to 200 MeV range, and a mechanism for galaxy formation. In the context of an open universe model, the value of omega which best fits the present gamma-ray data is omega equals approx. 0.1 which does not conflict with upper limits on Comptonization distortion of the 3K background radiation. In regard to He production, evidence is discussed that nucleosynthesis of He may have taken place after the galaxies were formed.
    Keywords: ASTROPHYSICS
    Type: ESA Recent Advan. in Gamma-Ray Astronomy; p 201-206
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 81
    facet.materialart.
    Unknown
    Prospects for computational aerodynamics (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The integral representations approach, for the solution of the Navier-Stokes equations is discussed as well as experience in its development and in applying available finite-difference and finite-element techniques to the treatment of three-dimensional problems, and the computation of turbulent flow. The magnitude of efforts required to develop turbulence models and three-dimensional algorithms indicates that the computational fluid dynamics research must have a broad base. Broader access to modern computing facilities that are in existence within NASA should be promoted for active researchers not directly affiliated with that agency.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Future Computer Requirements for Computational Aerodynamics; p 221-227
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 82
    facet.materialart.
    Unknown
    Modeling of the Reynolds stresses (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: In their most general form, the Reynolds averaged conservation equations result from ensemble or time averages of the instantaneous Navier-Stokes equations or their compressible counterparts. For these averaging processes to be consistent, the averaging time period must exceed the periods identified with the largest time scales of the turbulence, and yet be shorter than the characteristic times of the flow field. With these equations long period variations in the flow fields are deterministic, provided initial conditions are known. The average dependent variables are sufficiently smooth to be resolvable by finite difference techniques consistent with the size and speed of modern computers.
    Keywords: AERODYNAMICS
    Type: Future Computer Requirements for Computational Aerodynamics; p 239-247
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 83
    facet.materialart.
    Unknown
    Computational aerodynamics and the numerical aerodynamic simulation facility (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Technical and economic reasons for accelerating the maturation of the discipline of computational aerodynamics include the cost of conducting the experiments required to provide the empirical data base for new aeronautical vehicles and the limitations in test facilities (Reynolds number, wall and support interferences, aeroelastic distortions, real-gas effects, etc.) for simulating the full-scale vehicle environment. General purpose computers do not have the necessary capability for the next stage of development. Solution of the three dimensional Reynolds averaged Naiver-Stokes equations in a short time to be practical for design purposes will require 40 times the power of current supercomputers. However, it is feasible to construct a special purpose processor that will meet these requirements to enhance the nation's aerodynamic design capability in the 1980's.
    Keywords: AERODYNAMICS
    Type: Future Computer Requirements for Computational Aerodynamics; p 5-30
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 84
    facet.materialart.
    Unknown
    Landau damping and steepening of interplanetary nonlinear hydromagnetic waves (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: According to collisionless shock theories, the thickness of a shock front should be of the order of the characteristic lengths of the plasmas (the Debye length, the proton and Larmor radii, etc.). Chao and Lepping (1974), found, however, that 30% of the observed interplanetary shocks at 1 AU have thicknesses much larger than these characteristic lengths. It is the objective of the present paper to investigate whether the competition between nonlinear steepening and Landau damping can result in a wave of finite width that does not steepen into a shock. A heuristic model of such a wave is developed and tested by the examples of two structures that are qualitatively shocklike, but thicker than expected from theory. It is found that both events are in the process of steepening and their limiting thicknesses due to Landau damping are greater than the corresponding proton Larmor radius for both structures as observed at Mariner 5 (nearer the sun than 1 AU) but are comparable to the proton Larmor radius for Explorer (near 1 AU) observations.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research; 82; Oct. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 85
    facet.materialart.
    Unknown
    Carbon vaporization into a nonequilibrium, stagnation-point boundary layer (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The heat transfer to the stagnation point of an ablating carbonaceous heat shield, where both the gas-phase boundary layer and the heterogeneous surface reactions are not in chemical equilibrium, is examined. Specifically, the nonequilibrium changes in the mass fraction profiles of carbon species calculated for frozen flow are studied. A set of equations describing the steady-state, nonequilibrium laminar boundary layer in the axisymmetric stagnation region, over an ablating graphite surface, is solved, with allowance for the effects of finite rate of carbon vaporization.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 16; July 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 86
    facet.materialart.
    Unknown
    Perturbations in two- and three-dimensional transonic flows (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The difficulty of treating the perturbation of transonic flow, during which shock waves change position, can be overcome by using a distorted coordinate system in which the locations of all shock waves do not change; the distortion is found as part of the solution. This device leads to a relation that allows a range of flows, with differing shock locations, to be related algebraically to two known 'calibration' flows. Results for flows around finite wings, including those with multiple, intersecting shock waves, are presented. A typical computing time for such examples is 0.3 sec on a CDC 7600 computer.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 16; July 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 87
    facet.materialart.
    Unknown
    Gamma-ray lines - A new window to the Universe (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Gamma-ray emission is considered in terms of its usefulness in determining the physics of nucleosynthesis, the interstellar medium, solar flares, supernovae, and neutron stars. The mechanism of gamma-ray line emission is reviewed, i.e., nuclear deexcitation, radiative capture, positron annihilation, and possibly cyclotron radiation in the strong magnetic fields of neutron stars. Various gamma-ray spectra, obtained from balloon and satellite data, are analyzed with attention to solar particle energies and densities, including particle emission from black-hole supernova remnants.
    Keywords: ASTROPHYSICS
    Type: Physics Today; 31; Mar. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 88
    facet.materialart.
    Unknown
    New observations of ultraviolet variability in Wolf-Rayet stars (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Observations of ultraviolet variability in Wolf-Rayet stars have been made with the ANS satellite Ultraviolet Photometer Experiment. Significant variations are detected in several of the observed stars, the timescale of the variability ranging from a few minutes to several months.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 183
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 89
    facet.materialart.
    Unknown
    The nature of Aquila X-1 (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Photometry in the UBV spectra was used to observe Aquila X-1. This X-ray source, usually producing flux on the order of 1-10% that of the Crab Nebula, often behaves in a manner resembling the behavior of galactic X-ray stars. A description of the calibration methods used in the observations is presented, with attention to photoelectric-photographic methods. These observations suggest a quiescent spectral class near Ko, i.e., a dwarf at a distance of 1.6 kpc. The more intense X-ray emissions are said to be generated from internal heating of the stellar atmosphere, with additional energy supplied by a low-mass companion star. This explaination is at variance with the semi-detached Roche model.
    Keywords: ASTROPHYSICS
    Type: Nature; 271; Feb. 16
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 90
    facet.materialart.
    Unknown
    Evidence that cosmic gamma-ray bursts are galactic (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Balloon observations registering scatter angles in a liquid scintillator have revealed gamma-ray bursts having energies as low as 10 to the -7th ergs per square cm. The burst distribution is graphed according to energy and frequency. The hypothesis that the bursts are galactic in origin is in good agreement with their small recorded energies and their predicted distribution on the graph.
    Keywords: ASTROPHYSICS
    Type: Nature; 271; Feb. 16
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 91
    facet.materialart.
    Unknown
    Distance limit for a class of model gamma-ray burst sources (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: It is pointed out that MeV photons have actually been observed in bursts. These observations imply that the nonrelativistic sources cannot be further away than a few kpc from the sun and, therefore, must be galactic. The 27 April 1972 event observed by Apollo 16 shows at higher energies a power law spectrum with a possible line feature around 4 MeV. The optical depth of a homogeneous, isotropic radiation field is estimated with the aid of formulae used by Nikishov (1962) and Jauch and Rohrlich (1955). On the basis of an investigation of the various factors involved, it is tentatively suggested that the gamma-ray bursts which have been detected are galactic, but are in the majority of the cases not connected with unique irreversible star transformation. It appears also unlikely that the gamma-ray bursts are connected with galactic novae.
    Keywords: ASTROPHYSICS
    Type: Nature; 271; Feb. 9
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 92
    facet.materialart.
    Unknown
    Study of the luminosity function for field galaxies (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Nine determinations of the luminosity function (LF) for field galaxies are adjusted, analyzed, and compared. Adjustments are made for differences in definitions as well as in assumptions regarding magnitude systems, the Hubble constant, and galactic absorption. Eight of the nine adjusted determinations are found to be in fairly good agreement, and the discrepancy in the ninth is attributed to incompleteness effects. A large-scale normalization of the LF is performed using the method and some integral counts of Gott and Turner (1976); the large-scale mean LF of (mostly field) galaxies is found to be about 2.3 times less than a previously derived 'local' LF. The large-scale luminosity density in space arising from sources within the B(0) isophotes of galaxies is evaluated, and a value of 86 million (H/50) suns per cu Mpc is obtained for a galactic absorption coefficient of 0.25 magnitude. It is noted that the true large-scale luminosity density is probably within a factor of 1.6 of the reported value.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 82; Nov. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 93
    facet.materialart.
    Unknown
    Wall cooling effects on hypersonic transitional/turbulent boundary layers at high Reynolds numbers (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The characteristics of a thick hypersonic boundary layer turbulent for a length of 175 cm on a 4 deg sharp wedge were measured. The resulting boundary layer was free from transverse curvature effects and only mildly affected by upstream history effects caused by pressure and wall temperature gradients. Heat-transfer distributions were used to locate regions of laminar, transitional, and turbulent flow at an edge unit Reynolds number of 470,000 cm at wall-to-total temperature ratios from about 0.3 to 1. Wall cooling had little effect on the location of the transition region. Pitot and total temperature profiles and skin-friction measurements were obtained at several locations along the model longitudinal centerline. Mixing length and turbulent Prandtl number distributions were derived from the fully turbulent mean profiles.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 15; Oct. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 94
    facet.materialart.
    Unknown
    Numerical solution for supersonic flow near the trailing edge of a flat plate (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: In the present study, problems of laminar and turbulent two-dimensional flow of a viscous compressible fluid near the trailing edge of a thin flat plate are considered. The complete set of Navier-Stokes equations is solved by the finite-difference method of MacCormack (MacCormack and Baldwin, 1975). It is an explicit, predictor-corrector, time-splitting method of second order acuracy. The computational mesh employed has sufficient resolution for all the characteristic lengths suggested by theory. In the laminar case, the present results are compared with the triple deck solution of Daniels (1974). This comparison indicates that the asymptotic triple deck theory for supersonic trailing edge flow is accurate within five percent for Reynolds numbers greater than 1000. In the turbulent case, the Prandtl-Van Driest-Clauser algebraic eddy viscosity model is used. The numerical results show that the region of upstream influence is approximately of the order of the boundary layer thickness. The solutions for skin-friction, pressure and wake center-line velocity are presented.
    Keywords: AERODYNAMICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 95
    facet.materialart.
    Unknown
    Supernovae and the formation of the solar system (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The evidence that a supernova explosion may have triggered the formation of the solar system is reviewed. It cannot be said on the basis of the investigation that the supernova trigger is absolutely necessary for planetary system formation. However, it does appear according to the isotopic evidence that a supernova did blow up within a few million years of the solidification of objects in the solar system. If such an event occurred, it is reasonable to assume that the resultant supernova shock had a causal connection with the formation of the solar system and that a supernova may be one stimulus for formation of low-mass stars.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 96
    facet.materialart.
    Unknown
    Star formation in molecular clouds (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A general overview is presented of the findings of molecular line and infrared astronomy regarding star formation. Beginning with the statement that stars, and therefore, planets, form from molecular clouds, it is argued that the growing body of data on conditions in molecular clouds should serve as input parameters for theoretical calculations of star and planet formation. The fact that the gravitational potential energy of molecular clouds far exceeds their thermal energy implies that the required rate of star formation is easily explained. Indeed the most important problem in this field is that the rate of star formation predicted from molecular cloud studies is too high. Until this problem is understood, additional modes of inducing star formation, while they may be occurring, only add to the existing difficulties.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 97
    facet.materialart.
    Unknown
    The cloudy state of interstellar matter (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The expression 'cloudy state' is used to describe the state of the diffuse interstellar matter, with emphasis on its denser and more opaque regions. Questions of morphology with respect to the Galaxy are examined, taking into account neutral hydrogen, molecular regions, H II regions, infrared sources and masers, coronal gas in the Galaxy, and the major components of the interstellar medium. Aspects of dynamics are also considered, giving attention to the two-phase interstellar medium, the three-phase interstellar medium, the density-wave compression of clouds, and problems related to the concept of collapsing clouds. Developments concerning chemistry are explored. Radioactive chronologies are discussed along with isotopic anomalies and aspects of interstellar chemistry.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 98
    facet.materialart.
    Unknown
    Unsteady vortical and entropic distortions of potential flows round arbitrary obstacles (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The analysis concerns the alterations produced when small amplitude disturbances, including entropy and vorticity disturbances, are imposed on steady potential flows. For the most general nonacoustic incident distortion field that can be imposed on the uniform upstream flow, it is shown that the perturbation velocity at any point of the resulting unsteady compressible and vortical flow consists of a part that is a known function of the imposed upstream distortion field and the mean flow variables and a potential part that can be found by solving a linear inhomogeneous wave equation with a dipole-type source term whose strength is a known function of the imposed upstream distortion field. The theory is applied to the unsteady flow past a corner, and a closed-form analytical solution is found.
    Keywords: AERODYNAMICS
    Type: Journal of Fluid Mechanics; 89; Dec. 13
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 99
    facet.materialart.
    Unknown
    Some implications for interstellar molecules of a low electron abundance in dense clouds (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 83; Dec. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 100
    facet.materialart.
    Unknown
    Discovery and optical identification of 2S0921-630 (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The discovery of a faint X-ray source at approximately 282 deg galactic longitude, -9 deg galactic latitude with the rotation modulation collimator X-ray detectors aboard SAS 3 is reported. The source is designated 2S 0921-630 and is tentatively identified, on the basis of an optical search, with a 17th magnitude star exhibiting the He II line at 4686 A and H-beta in emission. The optical spectrum of this star is shown to be similar to those of the optical counterparts of Sco X-1 and other such galactic X-ray sources. It is suggested that 2S 0921-630 may belong to the class of low-luminosity galactic X-ray binaries.
    Keywords: ASTROPHYSICS
    Type: Nature; 276; Dec
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...