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
  • Other Sources  (1,707)
  • NASA Technical Reports  (1,707)
  • ASTROPHYSICS  (1,112)
  • FLUID MECHANICS AND HEAT TRANSFER  (595)
  • 1980-1984  (1,707)
  • 1982  (908)
  • 1980  (799)
Collection
  • Other Sources  (1,707)
Source
  • NASA Technical Reports  (1,707)
Keywords
Years
  • 1980-1984  (1,707)
Year
  • 1
    facet.materialart.
    Unknown
    Full-coverage film cooling (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Transpiration cooling is treated and then full coverage discrete hole injection for three injection orientations. Spacings with pitch to diameter ratios of 5 and 10 are discussed. The array is staggered, with the transverse pitch and the streamwise pitch the same. Results are presented in terms of the Stanton number using the heat transfer coefficient defined in terms of the difference between the wall temperature and the free stream temperature. Two values of Stanton number are provided for each situation: one with the injectant at wall temperature, and the other with the injectant at free stream temperature. These two values are equivalent to knowing the heat transfer coefficient and the adiabatic effectiveness. The heat transfer coefficient thus defined is used with the actual wall temperature to and the actual gas temperature to calculate the heat load. The principle of superposition thus invoked is valid exactly when the governing equations are linear.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Von Karman Inst. for Fluid Dyn. Film Cooling and Turbine Blade Heat Transfer, Vol. 1; 27 p
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Heat loss and drag of spherical drop tube samples (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Analysis techniques for three aspects of the performance of the NASA/MSFC 32 meter drop tube are considered. Heat loss through the support wire in a pendant drop sample, temperature history of a drop falling through the drop tube when the tube is filled with helium gas at various pressures, and drag and resulting g-levels experienced by a drop falling through the tube when the tube is filled with helium gas at various pressures are addressed. The developed methods apply to systems with sufficiently small Knudsen numbers for which continuum theory may be applied. Sample results are presented, using niobium drops, to indicate the magnitudes of the effects. Helium gas at one atmosphere pressure can approximately double the amount of possible undercooling but it results in an apparent gravity levels of up to 0.1 g.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: the 1981 NASA(ASEE Summer Fac. Fellowship Program; 31 p
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Kinetic theory in astrophysics and cosmology (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Results associated with exact solution of the Einstein-Boltzmann and Einstein-Maxwell-Boltzmann equations are presented. The generalization of Ehler's killing vector approach for the distribution function to charged particles is considered.
    Keywords: ASTROPHYSICS
    Type: Alabama Univ. in Huntsville The 1981 NASA(ASEE Summer Fac. Fellowship Program; 21 p
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Transient thermocapillary flow in thin liquid layers (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Surface-Tension Gradient Induced Flows at Reduced Gravity; 24 p
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Surface-tension gradient induced flows at reduced gravity, introduction (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Surface-Tension Gradient Induced Flows at Reduced Gravity; 21 p
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    The effect of rotation on the hydrodynamics of stellar collapse (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Fragmentation in rotating isothermal protostellar clouds (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The paper reports results of an extensive set of three-dimensional hydrodynamic calculations performed to investigate the susceptibility of rotating clouds to gravitational fragmentation; only isothermal collapse sequences were considered. It is found that rotating isothermal gas clouds are unstable to fragmentation under a wide range of conditions. The degree of instability and the mode (ring vs. blob) of fragmentation is sensitive to alpha, but insensitive to beta. The initial amplitude of a perturbation does not appear to be crucial; fragmentation should occur eventually even for low-amplitude initial NAPs.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    Spectroscopic and polarimetric observations of NGC 1333 and the surrounding dark cloud complex (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Spectroscopy and polarimetry of several very red stars, noted on Near Infrared Photographic Sky Survey photographs in the region of NGC 1333, have yielded a 'map' suggesting the extent of polarization arising from a two-cloud structure in the region. Spectral types and color indices of the stars make it possible to infer that grain radii in the clouds exceed typical interstellar medium values and, further, that they increase with optical depth into the cloud. The present observations indicate that the cloud structure is far more extensive than previously realized.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 85; Dec. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    Collapse and equilibrium of rotating, adiabatic clouds (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A numerical hydrodynamics computer code analysis of the collapse and establishment of equilibrium of adiabatic gas clouds restricted to axial symmetry found that the clouds are originally uniform in density and rotation. The method can compare the dynamic collapse and approach to equilibrium with the data on incompressible uniformly rotating equilibrium clouds and on equilibrium structures of differentially rotating polytropes. It is concluded that the stellar formation theory indicates that the low alpha fragments produced at the termination of the dynamic isothermal collapse phase of interstellar clouds may undergo significant dynamic collapse in an adiabatic regime leading to transitory ring formation and additional fragmentation on a smaller scale.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    Comparisons of interstellar CH/+/ and H2 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Copernicus observations of H2 toward stars in the Pleiades and 23 Orionis have been obtained because of their importance in understanding the formation of interstellar CH(+). No model of CH(+) equilibrium seems to agree very well with these observations; in particular, the suggestions that CH(+) is formed either from collisions between vibrationally excited H2 and C(+) or from radiative association of C(+) and H2 can apparently be excluded. These data do suggest that there is a correlation between the amounts of rotationally excited H2 and CH(+) which are present. Observations of the Pleiades also help interpretations of the reflection nebulae near these stars.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 11
    facet.materialart.
    Unknown
    Axial rotation, tangled magnetic fields, and theoretical models of very massive stars (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A simple method of computing theoretical models of very massive stars endowed with fast axial rotation and tangled magnetic fields is described and used in the present paper. Both of the two perturbing (nongravitational) forces induce changes in the luminosity and radius that are studied as functions of zero-age chemical composition, opacity, and evolutionary state of the interior. The central condensation of the star is found to have a significant influence on shifts of the upper main-sequence band in the H-R diagram if the perturbing force is concentrated in the stellar envelope (but not if the perturbing force is distributed so as to be approximately proportional to gravity everywhere); the layers of the envelope that contribute most heavily to the central condensation lie approximately at a radius fraction of r/R = 0.5. It is shown that fast uniform rotation and intense envelope magnetic fields lead to probably the largest possible shifts of the main-sequence band in the H-R diagram that rotation and magnetic fields can induce. These displacements are, however, too small to account for the total width of the observed main-sequence band at luminosities brighter than log (L/solar luminosity) = 4.5.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 12
    facet.materialart.
    Unknown
    The evolution of supernova remnants in different galactic environments and its effects on supernova statistics (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: It is shown that only a small fraction of the many supernovae in the Galaxy produces observable supernova remnants; this fraction, which is found to depend weakly on the lower mass limit of the SN progenitors, and more strongly on the specific characteristics of the associated interstellar medium, decreases from about 15% near the galactic center to 10% at R(gal) of about 10 kpc and drops nearly to zero for R(gal) greater than 15 kpc. Whether an SNR is detectable is determined by the density of the ambient interstellar medium in which it is embedded; it is found that SNRs are detectable only above some critical density (about 0.1 per cu cm). The presence of large low-density superbubble cavities around stellar associations due to the combined effects of stellar winds and supernova shells strongly suggests that a large portion of the detectable SNRs must have runaway stars as their progenitors.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 13
    facet.materialart.
    Unknown
    The unique cosmic event of 1979 March 5 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The transient gamma-ray burst observed on March 5, 1979 by the nine spacecraft forming the interplanetary gamma-ray burst network is discussed. Measurements reveal the event to be unlike any previously observed gamma-ray burst or X-ray burster, with a maximum intensity greater than several thousandths erg/sq cm per sec, a rise time of less than 200 microsec, a narrow and featureless initial spike and a regular 8-sec oscillation with a compound pulse shape. The source of the transient has been localized to a region including the supernova remnant N 49 in the Large Magellanic Cloud, at a distance of 55 pc, and a ratio of X-ray point-source steady state to transient emission of less than 10 to the -9th was obtained. The identification of the burst source with the supernova remnant at that distance would require an enormous source output if it was radiated isotropically, and substantially less if beaming is present. Alternatively, the event could be explained by a nearby, invisible neutron star.
    Keywords: ASTROPHYSICS
    Type: Comments on Modern Physics; vol. 9
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 14
    facet.materialart.
    Unknown
    On the phase-locked polarization variations in Cygnus X-1 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The paper presents data on the accumulated V-band orbital phase curves of polarization in Cygnus X-1 which disagree with the analysis of Simmons, Aspin, and Brown (1980). No curves which conform to the canonical model were observed, and a noncanonical structure is indicated by F tests on third, fourth, and fifth harmonics, which have a probability of 0.85 as a group. The fifth harmonic has a probability of 0.99; in contrast, the fundamental harmonic has a probability of only 0.6, which is below the detection threshold. Therefore, major conclusions of Simmons et al based on a nonsymmetrical canonical model assuming that fundamental harmonics are present, but harmonics with n greater than 2 are absent, are unacceptable. Analysis of the author's data by Simmons et al is criticized on the grounds that he did not take into account the cumulative aspects of the data and did not recognize the need to average out the random noise generated by Cygnus X-1 over many orbital cycles.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 91; 1-2,; Nov. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 15
    facet.materialart.
    Unknown
    The X-ray structure of two rich galaxy clusters and its implications for the detectability of microwave diminutions (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The X-ray observations of the galaxy clusters Abell 2319 and 576 show a reduced temperature of the microwave background due to the Suniaev-Zeldovich effect. The X-ray maps indicate smooth emission in these clusters concentrated toward the optical center; the surface brightness in the 1-3 keV band falls with the inverse square of radius outside a small core, and fits the Hubble's law of optical surface brightness of elliptical galaxies. The low temperature indicates that in A576 (1) the core radius of the gravitational potential is two to three times larger than inferred from galaxy counts, (2) the temperature rises with radius over most of the cluster and falls to zero at large radii, and (3) the gas does not obey the equation of state.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 16
    facet.materialart.
    Unknown
    Radial accretion of H-rich material onto a He white dwarf (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The nova outburst is modeled by spherically accreting H-rich material onto a 1 solar mass He white dwarf at a rate of 10 to the -8th solar mass/yr. The star accretes for 5848 years, when the nuclear reactions run away near the base of the accreted envelope. The nuclear-energy generation rate rises to 4.6(8) solar luminosities, and the envelope expands in response to it. However, nova-like mass ejection does not occur because the envelope is of insufficient mass, the base of the envelope is only mildly electron degenerate, and there is no enrichment of the CNO abundance. To overcome these limiting conditions, it is suggested that the H-rich material be accreted either more slowly than 10 to the -10th solar mass/yr or with angular momentum. Outbursts resulting in the former case should be similar to the nova models computed by Starrfield, Truran, and Sparks. Outbursts in the latter case should be strengthened, and novae might result because the H-rich material will be mixed into the surface layers of the white dwarf, as first suggested by Kippenhahn and Thomas (1978).
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 17
    facet.materialart.
    Unknown
    A numerical study of the effects of heat diffusion through the base of the mixed layer (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: In the present paper, a simple numerical model is used to study the warming of the mixed layer during the early summer. It is shown that the springtime temperature increase in the layer below the mixed layer (for example, in the cold pool on a continental shelf) has a maximum value which occurs for a limiting value of the surface heat flux. This is a result of the positive feedback at large Richardson numbers between stability and vertical diffusion of heat. The springtime temperature increase in the mixed layer increases nonlinearly with surface heat flux, because of the same positive feedback. The effects of interseasonal fluctuations of the surface heat flux on the spring and summer mixed layer and deeper temperature increases can be as great as the effect of interseasonal fluctuations of the average heat flux.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Geophysical Research; 85; Sept. 20
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 18
    facet.materialart.
    Unknown
    Spontaneous formation of knots in relativistic flows - A model for variability in compact synchrotron sources (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A model is proposed in which regions of enhanced synchrotron emission are formed via radiative thermal instabilities in relativistic flows. A perturbed volume in which the magnetic field is enhanced by a few tens of a percent relative to the steady value collapses due to the increased cooling rate and consequent loss in pressure. The collapse further increases the magnetic field, leading to even shorter radiative lifetimes. The instability progresses in this way until either the external electron pressure is balanced by the perturbed magnetic pressure or the overall expansion of the flow becomes important. A fluid-dynamical treatment of the instability is performed, and the results are shown to apply to flux variations and formation of knots in the relativistic flows which are thought to occur in quasars and active galactic nuclei. The knots possess the same kinematic properties as the collimated flow and can thus be responsible for the apparent superluminal motions observed in compact radio sources.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 19
    facet.materialart.
    Unknown
    Binary model of Circinus X-1. I - Eccentricity from combined X-ray and radio observations (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A binary star model is used to account for the 16.59-d flaring behavior of the X-ray emission from Circinus X-1. The orbital eccentricity of 0.8 + or - 0.1 is derived from the X-ray light curve by assuming that the sharp X-ray cut-off every 16.59-d is a result of bound-free absorption in the primary star's stellar wind. The shape of the light curve has changed over the last eight years, and this is interpreted as due to orbital precession of the binary system. Simultaneous radio and X-ray observations of the flare from Circinus X-1 on February 1-5, 1978 are reported. These are accounted for within the framework of the model. The radio observations at 5 GHz are used independently to derive a high value of the orbital eccentricity (e = 0.7).
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 86; 3, Ju; July 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 20
    facet.materialart.
    Unknown
    IUE observations of the atmospheric eclipsing binary system Zeta Aurigae (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: IUE observations of the eclipsing binary system Zeta Aurigae made prior to and during the eclipse of the relatively small B8 V star by the cool supergiant star (spectral type K2 II) are reported. Spectral lines produced by the absorption of B star radiation in the atmosphere of the K star during eclipse can be used as a probe of the extended K star atmosphere, due to the negligible cool star continuum in the 1200-3200 A region. Spectra taken prior to eclipse are found to be similar to those of the single B8 V star 64 Ori, with the exception of very strong multi-component absorption lines of Si II, Si IV, C IV and the Mg resonance doublet with strong P Cygni profiles, indicating a double shell. Absorption lines including those corresponding to Al II, Al III, Cr II, Mn II, Fe II, Ni II and Ca II are observed to increase in strength and number as the eclipse progresses, with high-ionization-potential lines formed far from the K star, possibly in a shock wave, and low-ionization potential lines, formed in cool plasma, probably a cool wind, nearer to the K star. Finally, an emission-line spectra with lines corresponding to those previously observed in absorption is noted at the time the B-star continuum had disappeared.
    Keywords: ASTROPHYSICS
    Type: Nature; 286; Aug. 7
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 21
    facet.materialart.
    Unknown
    The high-energy X-ray spectrum of Scorpius X-1 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 22
    facet.materialart.
    Unknown
    Quasi-stellar objects in the intergalactic medium - Source for the cosmic X-ray background (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Current estimates of QSO luminosity, number density, evolution, and spectral index are used to study whether the diffuse cosmic ray background is (1) entirely due to thermal bremmstrahlung of the intergalactic medium (IGM), (2) completely supplied by QSO X-rays, or (3) a combination of both. The upper limits on an IGM fractional density with respect to closure are Omega = 0.26, 0.24, and 0.21 for pure collisional, photo/collisional, and pure photoionization, respectively. These calculations give emission spectra, Compton distortion of the microwave background, and optical depths to distant QSOs for comparison with relevant data.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 23
    facet.materialart.
    Unknown
    New class of asymmetric shapes of rotating liquid drops (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Shapes and stability of surface-tension-endowed drops rotating rigidly at fixed angular momentum are calculated by finite-element analysis. A new family of asymmetric two-lobed drop shapes is discovered that branches from, and rejoins, the Pik-Pichak family of symmetric two-lobed shapes. The computations are verified for axisymmetric and symmetric two-lobed drop shape by comparison with previous approximations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physical Review Letters; 45; July 21
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 24
    facet.materialart.
    Unknown
    A model of comet comae. II - Effects of solar photodissociative ionization (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Improvements to a computer model of coma photochemistry are described. These include an expansion of the chemical reactions network and new rate constants that have been measured only recently. Photolytic reactions of additional molecules are incorporated, and photolytic branching ratios are treated in far greater detail than previously. A total of 25 photodissociative ionization (PDI) reactions are now considered (as compared to only 3 PDI reactions previously). Solar PDI of the mother molecule CO2 is shown to compete effectively with photoionization of CO in the production of observed CO(+). The CO(+) density peak predicted by the improved model, for CO2 or CO mother molecules, is deep in the inner coma, in better agreement with observation than the old CO2 model. However, neither CO2 nor CO mother molecule calculations reproduce the CO(+)/H2O(+) ratio observed in comet Kohoutek. PDI products of CO2, CO, CH4, and NH3 mother molecules fuel a complex chemistry scheme, producing inner coma abundances of CN, C2, and C3 much greater than previously calculated.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 25
    facet.materialart.
    Unknown
    Laser spectroscopy of the CN radical and astrophysical applications (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The formation of CN radicals by flash photolysis of a number of parent molecules was monitored by laser induced fluorescence in the B2Sigma(plus)-X2Sigma(plus) transition of CN. The rotational and vibrational energy of the newly formed radicals in the X state was measured directly. Formation of CN(A2Pi) in the lower vibrational levels was determined by an indirect method based on resonant energy transfer to higher vibrational levels of the ground state. These laboratory studies have shown that high initial internal excitation of CN with rotational levels of maximum N equals 50-70 is the rule. In general, the formation of simple molecules in excited states is commonly the case. There appear to be astrophysical systems where radiation from these excited levels may be detectable. Such observations would serve as a probe of molecular formation.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 26
    facet.materialart.
    Unknown
    The spectrum of IRC + 10216 from 2.0 to 8.5 microns (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Low-resolution spectra of IRC + 10216 have been obtained from 2 to 8.5 microns from NASA's Kuiper Airborne Observatory at an altitude of 12.5 km (41,000 feet). Observations were made during 1976 January and 1977 February. In both sets of data, the spectral flux reaches its maximum between 6.0 and 6.6 microns and the previously reported 3.1-micron feature is observed; no obvious new absorption features have been found. The new data together with other spectral data and measurements of the spatial extent of IRC + 10216 impose conditions that must be met by models of the continuum. Several simple models for 2-8.5 micron radiation are examined. The new continuum data impose a constraint on the size of the grains in the cooler, optically thin part of the object. Earlier photometry has been combined with the present data to yield an improved value of the average period: 644 + or - 17 days. It appears that the variability is irregular and that the minima have been deeper in recent years than they were in 1965-1969.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 27
    facet.materialart.
    Unknown
    Self-gravitating gas flow in barred spiral galaxies (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A series of two-dimensional numerical experiments is performed in order to test the response of an isothermal, self-gravitating gas disk to a uniformly rotating, barlike gravitational potential. The barlike potential is an equilibrium stellar model from the n-body calculations of Miller and Smith (1979). In the bar-dominated, central regions of the disk, a gas bar whose phase depends primarily on the location of principal resonances in the disk is formed. This response can be understood in terms of orbit-crowding effects. In the gas-dominated outer regions of the disk, two-armed trailing spiral waves are formed. The local pitch angle of these waves increases with increasing fractional gas mass. These self-gravitating gas waves are not self-sustaining. They are driven from the ends of equilibrium stellar bars, and their phase does not depend on the location of resonances in the disk. The relevance of these self-gravitating waves to observations and models of barred spiral galaxies is discussed. It is concluded that these waves and their associated ringlike structures may be consistent with the morphological distribution of gas features in barred spiral galaxies.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 28
    facet.materialart.
    Unknown
    Optical surface brightnesses of dusty galaxies (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: It is suggested that Freeman's (1970) result that the disk portions of spiral galaxies have a preferred central surface brightness might be the consequence of observing optically thick ensembles of a standard mix of stars and dust. Regardless of whether this hypothesis is correct, the observation that elliptical galaxies usually have central surface brightnesses considerably greater than the disk portions of spirals can be understood if there is much less dust within the elliptical systems. In particular, ellipticals probably have dust-to-total-mass ratios at least a factor of 100 smaller than in the disk portions of spirals, although there is no evidence that the dust-to-interstellar-gas ratios are different. When stars were forming within ellipticals, these galaxies were probably dustier than they are now, and their visible light output could have been substantially affected. It will probably be necessary to establish the dust content of galaxies as a function of redshift to use these objects as cosmological probes.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 29
    facet.materialart.
    Unknown
    New spectroscopic constants for methane derived by using microwave transitions from the interstellar medium (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 30
    facet.materialart.
    Unknown
    Comment on the paper 'A cosmological limit on the possible variation of G' (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 191
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 31
    facet.materialart.
    Unknown
    HEAO A-2 observations of the X-ray spectra of the Centaurus and A1060 clusters of galaxies (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: X-ray spectral observations of two nearby low-luminosity clusters of galaxies are presented. For the Centaurus cluster an emission feature at 7.9 keV is detected at about one-third of the strength of the 6.7 keV line. This higher energy line represents K-beta emission from highly ionized iron. In addition, it is demonstrated that for neither the Centaurus nor the A1060 cluster can an isothermal model with an Fe emission line adequately fit the data. Instead, the simplest models which provide acceptable fits include a second, harder component which may be either a second exponential or a power law. The implications of the two-component nature of the continuum on the Fe abundance and the X-ray surface-brightness distribution are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 32
    facet.materialart.
    Unknown
    Observation and search for gamma rays 1-20 MeV from the Crab, NGC 4151, Cyg X-1, Cyg X-3, CG 135+1 and 3C 273 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Observations and limiting values for the flux of 1-20 MeV gamma rays from the Crab, the Seyfert galaxy NGC 4151, the black hole candidate Cyg X-1, Cyg X-3 and the two nearest quasars CG 135+1 and 3C 273 are reported. Measurements of the energy and scatter angle of gamma rays at zenith angles between 10 and 30 deg were obtained by a balloon-borne double-scatter gamma-ray telescope. The flux from the Crab from 1.2 to 10 MeV is found to be 0.0039 + or - 0.0020 photons/sq cm per sec, and the energy distribution of the flux from 1.2 to 20 MeV is determined. Two-standard-deviation upper limits to the gamma-ray flux in the intervals 1.2-3, 3-5, 5-10 and 10-20 MeV of 0.0003, 0.0002, 0.00006 and 0.00004 photons/sq cm/sec are found for NGC 4151, Cyg X-1 and Cyg X-3, while those of 0.0005, 0.0003, 0.0001 and 0.00004 photons/sq cm per sec are determined for both quasars. These upper limits are interpreted as restricting confirmed gamma-ray sources to the Crab and NP 0532, and as evidence against Seyfert galaxies as the source of cosmic diffuse radiation.
    Keywords: ASTROPHYSICS
    Type: Nature; 284; Apr. 17
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 33
    facet.materialart.
    Unknown
    Simultaneous X-ray and optical observations of rapid variability in Scorpius X-1 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Copernicus and SAS-3 observations of Sco X-1 during very active states show strong and rapid X-ray flickering with time scales as short as 20 sec. Simultaneous optical photometry reveals similar and remarkably well correlated flickering of lower amplitude. The level of correlation decreases when the X-ray source becomes fainter, but optical and X-ray fluxes, averaged over 1 min, are usually well correlated for B magnitudes less than 12.9. Cross-correlation analysis of the data during periods of high activity shows no really significant time delay between X-ray and optical features, although the cross-correlation function peaks systematically for positive lag values (optical following X-rays). The amplitude of the X-ray flickering exhibits a strong energy-dependence consistent with the well-known intensity versus spectral-hardness relation derived from previous observations. The highly correlated optical activity is interpreted as due to reprocessing of X-ray photons in the binary system.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 191
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 34
    facet.materialart.
    Unknown
    Mass loss from UW Canis Majoris (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The present analysis is an application of the theory described by Lucy (1971) for the calculation of P Cygni resonance line profiles formed by isotropic and coherent scattering in spherically symmetric expanding circumstellar envelopes. Copernicus satellite measurements of resonance features in the FUV spectrum of the O 7 supergiant UW Canis Majoris (= HD 57060) are compared with theoretical P Cygni profiles. Grids of line profiles are computed using four free parameters which contain information about the velocity law, ionization equilibrium, temperature, and envelope density. Thus, with the assumption of a spherically symmetric steady flow, and of solar element abundances, the stellar mass loss rate and the electron temperature of the expanding shell can be derived. The mass flow is treated in a fully transonic way, i.e., the Sobolev approximation is applied.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 83; 3, Ma; Mar. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 35
    facet.materialart.
    Unknown
    Normal and abnormal turbulent transport in a stratified medium (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The influences of memory effects, coupling between velocity and temperature fluctuations and tensorial transport properties on momentum and heat transfers in turbulent flow which do not follow the Boussinesq relation are examined. It is shown that the memory effect, represented by the Lagrangian of the velocity gradients, can account for the decoupling between the flux and the gradient, while the tensorial properties of the transport coefficients allow a normal Boussinesq-type transfer with memory and anomalous counter-gradient or gradient-less transport.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 36
    facet.materialart.
    Unknown
    Effect of temperature on surface noise (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: An experimental work is discussed whose objective was to obtain data that show the effect of temperature and temperature fluctuations on surface noise. This was accomplished experimentally by immersing a small chord airfoil in the turbulent airstream of a hot jet. The theory and experiment reported by Olsen (1976) provided a guide for designing and validating the hot jet experiment and for interpreting the data. It is shown that increased temperature causes a small decrease in the sound levels; at the same time it causes a shift in the spectra that is smaller but similar to the shift observed with subsonic hot jet noise.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 18; Mar. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 37
    facet.materialart.
    Unknown
    IUE observations of the hot components in two symbiotic stars (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Recent IUE observations reveal striking differences in the UV spectra of two symbiotic stars, R Aqr and RW Hya. RW Hya is found to be an unexpectedly intense source of UV radiation. The measurements reported demonstrate the presence of a hot component in each star, supporting the view that each is a binary system with a luminous red primary and a hot, subluminous companion. In one case, the hot companion manifests itself by exciting a compact nebulosity; in the other case the continuous spectrum of the hot star is directly detected, while the continuum of nebulosity excited by the hot star is detected at longer wavelengths.
    Keywords: ASTROPHYSICS
    Type: Nature; 284; Mar. 13
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 38
    facet.materialart.
    Unknown
    Collapsing cloud models for Bok globules (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The dynamic collapse of rotating gas clouds is calculated for a wide range of initial conditions. Properties of cloud models are compared with observed radio and optical properties of Bok globules, to test the hypothesis that globules undergo collapse and to determine parameters which are not easily observed. Five of the six globules studied are consistent with collapse models. It is inferred that these objects have masses of about 100 solar masses and ages smaller than their free-fall times. Inferred initial densities are much larger than minimum densities for gravitational collapse, suggesting that collapse is initiated by strong external compression or that globules are fragments of larger condensed clouds. Values inferred for the (C-13)O/H2 ratio are smaller than previous estimates and depend strongly on cloud density.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 39
    facet.materialart.
    Unknown
    Cosmological tests of the Hoyle-Narlikar conformal gravity (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: For the first time the Hoyle-Narlikar theory with creation of matter and a variable gravitational constant G, is subjected to the following cosmological tests: (1) the magnitude versus z relation, (2) the N(m) versus m relation for quasars, (3) the metric angular diameters versus z relation, (4) the isophotal angles versus z relation, (5) the log N-log S radio source count, and finally (6) the 3 K radiation. It is shown that the theory passes all these tests just as well as the standard cosmology, with the additional advantage that the geometry of the universe is uniquely determined, with a curvature parameter equal to zero. It is also interesting to note that the variability of G affects the log N-log S curve in a way similar to the density evolution introduced in standard cosmologies. The agreement with the data is therefore achieved without recourse to an ad hoc density evolution.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 40
    facet.materialart.
    Unknown
    Radial distribution of forbidden Fe X and forbidden Fe XIV emission in the Cygnus Loop. II (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 41
    facet.materialart.
    Unknown
    On C4H versus vibrationally excited CO in IRC + 10216 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The identification of the 114,221-MHz line in the spectrum of the evolved carbon star IRC +10216 with a blend of the rotational transition of C4H and the first rotational transition of vibrationally excited CO is investigated. A spectrum of the source was obtained using an 11-m telescope in the range covering the N = 12 to 11 and 11 to 10 spin-doublet rotational transitions of C4H. Two peaks of equal intensity and width are found in each band, suggesting a spin rotation constant of 1.06 for the 12 to 11 doublet and 1.09 for the 11 to 10 doublet, and excluding the possibility that vibrationally excited CO made any contribution to the 12 to 11 doublet. An additional survey of the regions from 103.8 to 107.5 and 113.3 to 117.0 GHz has revealed no new lines stronger than 0.1 K in the spectrum of IRC +10216.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 42
    facet.materialart.
    Unknown
    Case for an open universe (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The determination of the geometrical structure of the universe through the magnitude-vs-redshift relation in standard cosmology has not been very successful, mainly because of the intrinsic insensitivity of the m-vs-z relation to a deceleration parameter, which determines the spatial curvature and therefore the geometry. By relaxing the assumption usually made, i.e., the identity of gravitational and atomic clocks, sufficient sensitivity is achieved. Existing observational evidence then leads one to conclude that the universe is open.
    Keywords: ASTROPHYSICS
    Type: Physical Review Letters; 44; Mar. 17
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 43
    facet.materialart.
    Unknown
    The Crab Nebula's progenitor (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The initial mass of the Crab Nebula's progenitor star is estimated by comparing the observed nebular chemical abundances with detailed evolutionary calculations for 2.4- and 2.6-solar-mass helium cores of stars with masses of 8 to 10 solar masses. The results indicate that the mass of the Crab's progenitor was between the upper limit of about 8 solar masses for carbon deflagration and the lower limit of about 9.5 solar masses set by the dredge-up of the helium layer before the development of the helium-burning convective region. A scenario is outlined for the evolution of the progenitor star. It is suggested that the Crab Nebula was probably the product of an electron-capture supernova.
    Keywords: ASTROPHYSICS
    Type: Nature; 299; Oct. 28
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 44
    facet.materialart.
    Unknown
    Cosmic turbulence and the angular momenta of astronomical systems (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: It is suggested that gravitationally bound astronomical systems ranging from asteroids to galaxy superclusters may derive their rotation from a hierarchy of cosmic turbulence, thus explaining the empirical specific angular momentum-mass relationship (j approximately equal to M to the 3/4 power) exhibited by these systems. It is shown that many of the properties of these systems, e.g., the random orientation of their spin vectors, can be accounted for if astronomical objects form in a turbulent environment.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 261
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 45
    facet.materialart.
    Unknown
    Relativistic kinematics for motions faster than light (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-20197)
    Keywords: ASTROPHYSICS
    Type: vol. 35; Nov. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 46
    facet.materialart.
    Unknown
    Water as a probe of star-forming regions (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Preliminary calculations employing statistical equilibrium techniques were carried out to determine brightness temperatures of water transitions occurring in the submillimeter band. The interesting candidates appear to be the 325 GHz, 380 GHz, and 448 GHz transitions, they are compared with the 183 GHz and 380 GHz transitions observed in the Orion Kleinmann-Low nebula and the combined results seem to be consistent with H2 densities of 100,000 -1 million cm-3 and a water column density of approximately 10 to 18th power. This implies a relative abundance of approximately 0.00001 which means that water may be about one twentieth of CO. In addition, it was found that for the conditions of the Orion plateau source, the 448 GHz line is expected to be a mild maser.
    Keywords: ASTROPHYSICS
    Type: ESA The Sci. Importance of Submillimetre Observations; p 129-130
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 47
    facet.materialart.
    Unknown
    Turbulent boundary layer heat transfer (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Several environmental parameters presently acknowledged to affect heat transfer are discussed including: (1) the experimental apparatus used, (2) uniform and variable wall temperatures, (3) acceleration effects, (4) deceleration, (5) free stream turbulence, (6) surface roughness, (7) unsteady effects, and (8) secondary flows. Calculation procedures, and some physically based models that are successful in computing heat transfer rates are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Von Karman Inst. for Fluid Dyn. Film Cooling and Turbine Blade Heat Transfer, Vol. 1; 40 p
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 48
    facet.materialart.
    Unknown
    Curvature effects and turbulent boundary layers (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Results are examined from an experiment conducted to determine quantitatively the secondary factors which affect the response of a turbulent boundary layer to convex curvature and to examine the recovery process after curvature ended. The variation of Stanton number with streamwise distance and with enthalpy thickness Reynolds number for the baseline case is shown. The effect of delta sub .99/R on the velocity of the potential core would have if we extended to the wall with no viscous effects, of free stream acceleration, of an unheated starting length, and of boundary layer maturity are discussed. Mixing length and turbulent Prandtl number models are reviewed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Von Karman Inst. for Fluid Dyn. Film Cooling and Turbine Blade Heat Transfer, Vol. 1; 29 p
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 49
    facet.materialart.
    Unknown
    Radiation from the accretion column of magnetized neutron stars (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Some developments in radiative transfer for magnetized neutron star conditions, and their application in models of the structure and properties of self-consistent polar cap emission regions are reviewed. Several of the assumptions and uncertainties involved are discussed, and present problems are indicated.
    Keywords: ASTROPHYSICS
    Type: Max-Planck Inst. Phys. and Astrophys. Accreting Neutron Stars; p 253-274
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 50
    facet.materialart.
    Unknown
    Spectral evolution of active galactic nuclei - A unified description of the X-ray and gamma-ray backgrounds (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-22137)
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 260
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 51
    facet.materialart.
    Unknown
    On OMC-1 temperatures determined from methyl cyanide observations (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: An analysis is performed on the J(k) = 12(k)-11(k) and 13(k)-12(k) transitions of methyl cyanide detected by other investigators in the direction of OMC-1. The original interpretation of those observations argues for the presence of two distinct temperature regions or possibly a temperature gradient within the cloud. The analysis presented here demonstrates that the observations of these particular molecular transitions are consistent with a single methyl cyanide emission region with a source kinetic temperature of 121.2 + or - 8.2 K and a molecular rotational temperature of 16.6 + or - 1.8 K.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 260
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 52
    facet.materialart.
    Unknown
    A large scale height galactic component of the diffuse 2-60 keV background (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The diffuse 2-60 keV X-ray background has a galactic component clearly detectable by its strong variation with both galactic latitude and longitude. This galactic component is typically 10 percent of the extragalactic background toward the galactic center, half that strong toward the anticenter, and extrapolated to a few percent of the extragalactic background toward the galactic poles. It is acceptably modeled by a finite radius emission disk with a scale height of several kiloparsecs. The averaged galactic spectrum is best fitted by a thermal spectrum of kT about 9 keV, a spectrum much softer than the about 40 keV spectrum of the extragalactic component. The most likely source of this emission is low luminosity stars with large scale heights such as subdwarfs. Inverse Compton emission from GeV electrons on the microwave background contributes only a fraction of the galactic component unless the local cosmic ray electron spectrum and intensity are atypical.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 260
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 53
    facet.materialart.
    Unknown
    BL Herculis stars - Theoretical models for field variables (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Type II Cepheids with periods between 1 and 3 days, commonly designated as Bl Herculis stars, have been modeled here with the aim of interpreting the wide variety of light curves observed among the field variables. Previously modeled globular cluster members are used as standard calibration objects. The major finding is that only a small range of luminosities is capable of generating a large variety of light curve types at a given period. For a mass of approximately 0.60 solar mass, the models are able to reproduce the observed mean luminosities, dispersion of mean luminosities, periods, light amplitudes, light asymmetries, and phases of secondary features in the light curves of known BL Her stars. It is possible that the metal-rich variables (which are found only in the field) have luminosities lower than those of most metal-poor variables. The present revised mass for BL Her, a metal-rich object, is not significantly different from the mean mass of the metal-poor variables.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 259
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 54
    facet.materialart.
    Unknown
    A heuristic criterion for instability to fragmentation in rotating, interstellar clouds (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A heuristic criterion, based on linear perturbation analysis, is applied to the initial growth of density perturbations in isothermal or adiabatic gas clouds, with initially uniform density and uniform rotation. The heuristic criterion is shown to be consistent with the available results from numerical calculations of cloud collapse. The criterion predicts that perturbations varying as cos(m-phi) will be most likely to grow when m is small, unless the cloud is nearly pressureless.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 259
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 55
    facet.materialart.
    Unknown
    High energy X-ray observations of Cyg X-3 from OSO-8 - Further evidence of a 34.1 day period (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-18085)
    Keywords: ASTROPHYSICS
    Type: Astrophysical Letters; 22; 4, 19; 1982
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 56
    facet.materialart.
    Unknown
    Neutron star collisions and the r-process (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: It is shown that a natural consequence of the binary pulsar's evolution is a neutron star collision. Such a collision is expected to eject neutron-rich matter of an r-process character. Taking reasonable estimates for the number of such events over the history of the galaxy, it may be that they account for all of the r-process nuclei.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Letters; 22; 4, 19; 1982
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 57
    facet.materialart.
    Unknown
    The peculiar variable star R Aquarii and its jet (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Observations of the variable star R Aquarii from 1928 to the present are examined to conclude that the star is a binary system with a jet. The orbital period of the objects is estimated at 22 yr, and a supercritical mass transfer that occurs once every 44 yr is suggested as a mechanism to explain deep minima observed on two occasions that many years apart. Calculations presented for the critical accretion rate of the two Miras indicated that one of the objects possesses a substantially stronger gravitational field than the other and features a large accretion disk. Oriental astronomical records from 930 AD are cited as evidence that a nova occurred in the vicinity of R Aquarii at that time. The system is noted to be the closest jet thus far observed, and the accretion disk may be visible with the Space Telescope.
    Keywords: ASTROPHYSICS
    Type: Nature; 298; Aug. 5
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 58
    facet.materialart.
    Unknown
    The photospheric velocity field of Procyon (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Balloon-borne Ultraviolet Stellar Spectrometer observations of the profiles of two well observed spectral lines in the ultraviolet spectrum of Alpha CMI (Procyon; F5IV-V) are analyzed with a Fourier transform method in order to determine values of various parameters of the velocity field of the upper photosphere. A microturbulent line-of-sight velocity component of 0.9 + or - 0.4 km/s, a macroturbulent velocity component of 5.3 + or - 0.2 km/s, and a rotational velocity component of 10.0 + or - 1.2 km/s were determined. In these calculations a single-moded sinusoidal isotropic macroturbulent velocity function was assumed. The result appears to be sensitive to the assumed shape of the macroturbulence function.
    Keywords: ASTROPHYSICS
    Type: Astrophysics and Space Science; 84; 2, Ju; June 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 59
    facet.materialart.
    Unknown
    Analysis of the decay of temperature fluctuations in isotropic turbulence (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The Lagrangian dispersion theory of Durbin (1980) is used to analyze experiments by Warhaft and Lumley (1978) and by Sreenivasan et al. (1980) on temperature fluctuations in grid-generated turbulence. Both theory and experiment show that the decay exponent m depends on the ratio of the initial length scales of velocity and temperature, although when this ratio is greater than 2.5 such dependence is negligible. The theory shows that m is not truly constant, but within the range covered by the experiments it is nearly so. The agreement between theory and experiment lends credence to the idea that the decay of fluctuations is controlled largely by turbulent relative dispersion.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids; 25; Aug. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 60
    facet.materialart.
    Unknown
    On the structure of the outer layers of cool carbon stars (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Exposures on the spectra of four late C-type stars have been made with the IUE satellite in the wavelength range of the LWR camera (1900-3200 A). Two Mira variables near maximum light and two semiregular variables were observed. Although the exposure times used, which range up to 240 min in the low-resolution mode, were more than sufficient to record the continuum and emission lines of Mg II, Fe II, and Al II in normal M stars of similar magnitude and temperature, no light was recorded. It is concluded that the far-ultraviolet continuum is strongly depressed in these cool carbon stars. The absence of UV emission lines implies either that the chromospheric lines observed in M stars require an ultraviolet flux for their excitation, or that cool carbon stars have no chromosphere at all or that the opacity source is located above even the emission-line-forming region. This opacity source, which is probably some carbon condensate since it is weak or absent in M stars while absorbing strongly in C stars, is discussed both in terms of the chromospheric interpretation of the emission lines and in terms of their shock-wave interpretation.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 111; 1, Ju; July 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 61
    facet.materialart.
    Unknown
    A precessing relativistic jet model for 3C 449 (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: It is shown that the radio structure of 3C 449 can be matched with a model in which the jets are precessing and have relativistic (beta greater-than or equal to 0.4) velocities. The best-fit model implies a precession period of about 100,000 yr and a cone angle which increases with time. A similar model may be relevant for the radio structure of 3C 31. A brief discussion of the implications for 3C 449 is given.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 258
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 62
    facet.materialart.
    Unknown
    Collapse of accreting, rotating, isothermal, interstellar clouds (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The evolutions of the envelopes of collapsing, accreting, isothermal clouds have been numerically calculated for both spherically symmetric and rotating (axisymmetric) clouds. The results provide a cohesive picture of isothermal collapse, and their relationship to previous numerical calculations and similarity solutions is discussed. Even with a large initial rotation rate, the majority of the cloud envelope is accreted, in one case leaving behind a large-scale circulation current. The calculations are performed for both initially uniform density and centrally condensed clouds. Density and velocity profiles for a wide variety of observed systems are compared with those obtained in this study, providing a preliminary assessment of the stage of evolution and initial structure for the observed systems.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 258
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 63
    facet.materialart.
    Unknown
    Laboratory measurements of amorphous silicate smokes and the infrared spectra of oxygen-rich stars (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The infrared spectra of smokes condensed from SiO-H2 and Mg-SiO-H2 vapors and of smoke samples annealed for various times at 1000 K and 1250 K are presented. The spectra of these materials show features in the 8-25 micron interval in addition to the well-known bands near 10 and 20 microns. It is suggested that these features may correspond to weak structures that can be seen in the infrared spectra of oxygen-rich stars. Observations are needed to determine the reality and characteristics of such weak features.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 257
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 64
    facet.materialart.
    Unknown
    The distribution of free electrons in the inner Galaxy from pulsar dispersion measures (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-18096)
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 257
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 65
    facet.materialart.
    Unknown
    Star formation - The influence of velocity fields and turbulence (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: It is shown that the Jeans mass for gravitational collapse can be very much reduced by the influence velocity fields, even when allowance is made for non-isothermal gas behavior. We examine the role of turbulence in establishing the initial stellar mass function and show that the flattening and/or turnover at the low mass end may be a signature of interstellar turbulence. We consider also the implications of primordial turbulence for the formation of stars in the early universe.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 256
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 66
    facet.materialart.
    Unknown
    A model of a comet coma with interstellar molecules in the nucleus (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The coma of a comet is modeled assuming the icy nucleus contains interstellar molecules. This composition overcomes discrepancies between observation and earlier model predictions for CN, C2, C3, and NH2 abundances. It is found that the abundances of CN, C2, and C3-bearing compounds in the nucleus must be constrained to trace amounts in order to account for the observed column densities. NH3 also cannot be abundant by more than about 1%. The model gives good agreement with observed relative ranges of neutral species in the coma as well as with their observed relative intensity dependence on heliocentric distance. The size of the nucleus and the heliocentric ranges considered are relevant to comet Halley.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 108; 2, Ap; Apr. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 67
    facet.materialart.
    Unknown
    Radial evolution of power spectra of interplanetary Alfvenic turbulence (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-18097)
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research; 87; May 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 68
    facet.materialart.
    Unknown
    Infrared emission line studies of the structure and excitation of H II regions (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Maps of five H II regions in one or more of the infrared fine-structure lines of Ne II (12.8 microns), Ar III (9.0 microns), and S IV (10.5 microns) have been obtained with angular resolutions ranging from 4 to 7 arcsec. The observations are used to discuss the morphology and excitation of these nebulae. Considerable diversity is found in the structures of the nebulae, probably resulting from differences in their ages and the circumstances of their formation. In all cases, more ionizing luminosity than would be provided by a single dominant ionizing star appears to be required, although uncertainties in the model nebulae make this conclusion uncertain.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 255
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 69
    facet.materialart.
    Unknown
    Evidence for extended X-ray emission from globular clusters (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Deep exposures with the Einstein Observatory show evidence for diffuse X-ray emission from three globular clusters. One possible interpretation of these observations is that the interaction between a cluster wind and a hot gaseous galactic halo is being observed. The one cluster for which the proper motion has been measured is consistent with this interpretation.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 254
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 70
    facet.materialart.
    Unknown
    A different type of maser star (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A systematic survey of short-period, semiregular variable stars has been made resulting in the detection of six new water masers. Of the 14 short-period maser stars now known, nine are classified as SRb variables. All are very late spectral type SRb's, typically M7, while the overwhelming majority of normal SRb stars is M4 to M6. Their 2.2-11 micron color indices are among the lowest of any known maser stars. They are presumably less dusty as well. Four of the SRb stars and two of the remainder do not obey the correlation between period and velocity spread of the emission features that is found for the Mira and long-period, semiregular variables. Finally, high galactic latitudes dominate; 13 of the 14 are in excess of 13 deg, and nine of these are greater than 25 deg. These facts suggest that the short-period semiregular variables - particularly in SRb stars - may be a very different type of maser star than the Mira and long-period semiregular variables.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 254
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 71
    facet.materialart.
    Unknown
    The discovery of 50 minute periodic absorption events from 4U 1915-05 (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: An analysis of X-ray observations shows that the steady flux from 4U 1915-05 undergoes periodic absorption dips with a period of 50 minutes. This period most probably represents the underlying orbital period of the system, and variations in the depth and duration of these events suggest that they are caused by a bulge on the edge of the accretion disk at the point where the gas stream impacts the disk. The mass-losing star in this system is probably a low-mass white dwarf, and the spectrum of the dips indicates that the metallicity of the absorbing material is at least a factor of 17 below solar values. The discovery of the 50-minute binary period supports earlier suggestions that X-ray burst sources are in binary systems.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 253
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 72
    facet.materialart.
    Unknown
    Search for interstellar superheavy hydrogen (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Models for fundamental physical interactions allow for the existence of stable or nearly stable elementary particles much heavier than the proton. Stellar spectra were searched for a positively charged superheavy particle, X(+), which, with a bound electron, should appear as apparently superheavy neutral hydrogen in the interstellar medium. An upper limit for the abundance of X relative to normal hydrogen in the line of sight toward the bright star gamma Cassiopeiae is 2 x 10 to the -8th.
    Keywords: ASTROPHYSICS
    Type: Science; 216; Apr. 2
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 73
    facet.materialart.
    Unknown
    Resonant electrodynamic heating of stellar coronal loops - An LRC circuit analog (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The problem of electrodynamic coupling of stellar coronal loops where beta is less than 1 to underlying velocity fields where beta is greater than approximately 1 is treated. A rigorous analysis reveals that the physics can be represented by a simple yet equivalent LRC circuit analog. This derived analog suggests the existence of global structure oscillations which resonantly excite internal field line oscillations at a spatial resonance within the coronal loop. Even though the width of this spatial resonance, as well as the induced currents and coronal velocity field, within the resonance region explicitly depends on viscosity and resistivity, the resonant form of the generalized electrodynamic heating functions is virtually independent of irreversibilities. This is a classic feature of high-quality resonators that are driven externally by a broad-band source of spectral power.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 254
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 74
    facet.materialart.
    Unknown
    Observations of interstellar zinc (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: IUE observations toward 10 stars have shown that zinc is not depleted in the interstellar medium by more than a factor of two, suggesting that its abundance may serve as a tracer of the true metallicity in the gas. A result pertinent to the history of nucleosynthesis in the solar neighborhood is that the local interstellar medium has abundances that appear to be homogeneous to within a factor of two, when integrated over paths of about 500 pc.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 254
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 75
    facet.materialart.
    Unknown
    Axisymmetric inviscid swirling flows produced by bellmouth and centerbody (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The effect of large deformation in the flow between the bellmouth and centerbody is considered analytically for application to studies of vortex breakdown in a pipe. Basic equations are defined for axisymmetric inviscid swirling flows at the inflow and outflow sections. Axial and circumferential velocity component profiles are presented, and comparisons are made with trials involving vane angles of 42 deg and Re of 2300. Axial components of the prediction matched well in the inner half of the pipe radius and not well with the outer, while circumferential predictions were good only at the axis. A lack of viscosity was concluded to result in the inaccuracies near the wall.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 20; Apr. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 76
    facet.materialart.
    Unknown
    Electromagnetic cascades in pulsars (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The development of pair-photon cascades initiated by high energy electrons above a pulsar polar cap is simulated numerically. The calculation uses the energy of the primary electron, the magnetic field strength, and the period of rotation as parameters, and follows the curvature radiation emitted by the primary, the conversion of this radiation to e(+)e(-) pairs in the intense fields, and the quantized synchrotron radiation by the secondary pairs. A recursive technique allows the tracing of an indefinite number of generations using a Monte Carlo method. Gamma-ray and pair spectra are calculated for cascades in different parts of the polar cap and with different acceleration models. It is found that synchrotron radiation from secondary pairs makes an important contribution to the gamma-ray spectrum above 25 MeV, and that the final gamma-ray and pair spectra are insensitive to the height of the accelerating region, as long as the acceleration of the primary electrons is not limited by radiation reaction.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 252
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 77
    facet.materialart.
    Unknown
    Black holes, quasars, and the universe /2nd edition/ (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Topics of astronomy are discussed in terms of black holes, galaxies, quasars, and models of the universe. Black holes are approached through consideration of stellar evolution, white dwarfs, supernovae, neutron stars, pulsars, the event horizon, Cygnus X-1, white holes, and worm holes. Attention is also given to radio waves from high speed electrons, the radiation emitted by quasars, active galaxies, galactic energy sources, and interpretations of the redshift. Finally, the life cycle of the universe is deliberated, along with the cosmic time scale, evidence for the Big Bang, and the future of the universe.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 78
    facet.materialart.
    Unknown
    Turbulence and the stability of molecular clouds (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Molecular clouds may be stabilized against gravitational collapse by the turbulent velocity field within them. It is suggested that the energy derived from differential galactic rotation can maintain the turbulent flow in the interstellar medium. The characteristic decay time for interstellar turbulence is found to be about 10-billion years. The rate and efficiency of star formation in giant molecular clouds reflect the stochastic nature of turbulence.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 79
    facet.materialart.
    Unknown
    Gas diffusion in multibubble systems (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A model is proposed for the study of the growth and shrinkage of gas bubbles in systems containing many gas bubbles. The key feature of this model is the replacement of the bubbles by point sources of gas concentration. Calculations are performed in the simple case of an initial uniform array of bubbles of equal radii.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Chemical Engineering Science; 35; 1980
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 80
    facet.materialart.
    Unknown
    A wave model for dwarf novae (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The rapid coherent oscillation during a dwarf nova outburst is attributed to an accretion-driven wave going around the white dwarf component of the binary system. The increase and decrease in the period of this oscillation is due to the change in the velocity of the wave as it is first being driven and then damped. Qualitatively, a large number of observations can be explained with such a model. The beginnings of a mathematical representation of this model are developed.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 81
    facet.materialart.
    Unknown
    Collapse, equilibrium, and fragmentation of rotating, adiabatic clouds (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Numerical calculations of the collapse of adiabatic clouds from uniform density and rotation initial conditions show that when restricted to axisymmetry, the clouds form either near-equilibrium spheroids or rings. Rings form in the collapse of low thermal energy clouds and have a ratio of rotational kinetic energy to the absolute value of gravitational potential energy greater than approximately 0.43. When the axisymmetric constraint is removed and an initial m = 2 density variation is introduced, clouds either collapse to form near-equilibrium ellipsoids or else fragment into binary systems through a bar phase. Ellipsoids form in the collapse of high thermal energy clouds and have a rotational kinetic energy/absolute value of gravitational potential energy ratio less than approximately 0.27. The results are consistent with the critical values of the rotational kinetic energy/absolute value of gravitational potential energy ratio for instabilities in Maclaurin spheroids, and suggest that protostellar clouds may undergo a dynamic fragmentation in the nonisothermal collapse regime.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 82
    facet.materialart.
    Unknown
    Vortex methods for flow simulation (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Recent progress in the development of vortex methods and their applications to the numerical simulation of incompressible fluid flows are reviewed. Emphasis is on recent results concerning the accuracy of these methods, improvements in computational efficiency, and the development of three-dimensional methods. Simulations of several example flows which display some of the strengths and weaknesses of vortex methods are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics; 37; Oct. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 83
    facet.materialart.
    Unknown
    X-ray line emission from the supernova remnant G292.0 + 1.8 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The Solid State Spectrometer on the Einstein Observatory has detected line emission from Mg, Si and S in the thermal X-ray spectrum of the supernova remnant G292.0 + 1.8. An over-abundance of sulfur and a probable under-abundance of iron relative to their solar values is indicated by the data. The X-ray and optical data for this object support an interpretation of emission originating in ejecta from the comparatively recent explosion of a massive (about 20-solar-mass) progenitor star.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 193
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 84
    facet.materialart.
    Unknown
    A survey of chromospheric Ca II H and K emission in field stars of the solar neighborhood (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Fluxes in 1 A bands at the centers of the H and K lines are being measured in main-sequence F-G-K-M stars in the northern half of the Woolley et al. (1970) 'Catalog of stars within twenty-five parsecs of the sun', in a survey not yet completed. Results for 486 stars are presented in the form of flux-color diagrams and discussed in light of evidence that chromospheric activity declines with age in main-sequence stars. Support is noted for the reality of the Sirius moving group. The relative numbers of more-active (Hyades-like) and less-active (solar-like) F-G stars are tolerably in agreement with a nearly constant rate of formation, but there exists an apparent deficiency in the number of F-G stars exhibiting intermediate activity. The possibility that the gap is an accidental characteristic of the sample will be investigated by extending the survey to southern declinations and greater distances.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific; vol. 92
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 85
    facet.materialart.
    Unknown
    The X-ray pulsars 4U 1145-61 and 1E 1145.1-6141 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Observations of the neighboring X-ray pulsars 4U 1145-61 and 1E 1145.1-6141 obtained by OSO 8, HEAO 1 and the Einstein Observatory between 1975 and 1979 are reported. A temporal analysis of Einstein Solid State Spectrometer and Monitor Proportional Counter data, OSO 8 A and C detector data and HEAO 1 A-2(3) experiment data confirms the presence of two periodicites at 291 and 297 sec in the region, with the shorter period located within 3 arcmin of 4U 1145-61. Observations indicate the spectrum of 4U 1145-61 to obey a power law with an index of 1.5 out to at least 60 keV, with little variation with pulse phase, and a 500-eV EW iron line at 6.7 keV. The spectrum of the other source is found to be more absorbed. Similarities between the pulsars are noted, and it is suggested that they may be the result of pulsar formation in a homogeneous cloud of progenitors.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 86
    facet.materialart.
    Unknown
    Observations of Cygnus X-3 with the Einstein /HEAO 2/ X-ray Observatory The period derivative and the asymmetric X-ray light curve (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Cygnus X-3 was observed by the Monitor Proportional Counter on the Einstein (HEAO 2) X-ray Observatory for 2.4 days in 1978 December. The analysis of the data from these observations is used in conjunction with a self-consistent re-examination of previous results from the Uhuru, ANS, COS B, and SAS 3 satellites to investigate earlier reports that the 4.8 hour period of Cygnus X-3 is increasing. It is found that there is indeed a period derivative, P = (1.78 plus or minus 0.40) x 10 to the -9th s/s, which confirms the principal conclusion of previous authors. The possibility that the X-ray source is in an elliptical orbit and that some, or all, of the observed period derivative may be due to apsidal motion is discussed. The elliptic orbit hypothesis explains the observed asymmetry in the average X-ray light curve and leads to the conclusion that the most likely companion to the X-ray source is a helium star, possibly with a light hydrogen envelope
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 87
    facet.materialart.
    Unknown
    An observational H-R diagram for early-type stars (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: An observational H-R diagram for the O and B stars is discussed and compared with the predicted positions of massive model stars for the case of no mass loss and the case of mass loss. It is shown that the flux effective temperatures of O and B supergiants and of early O stars are less than the effective temperatures which might be inferred from the relative intensities of lines from two stages of ionization of an element.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 88
    facet.materialart.
    Unknown
    X-ray observations of the Seyfert 1 galaxies AKN 120 and MCG 8-11-11 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A new X-ray source, H0523-00, with the optically variable Seyfert 1 galaxy AKN 120 is identified. The source has a 2-10 keV X-ray flux of 2 x 10 to the -11th ergs/sq cm s which corresponds to a 2-10 keV X-ray luminosity of 10 to the 44th ergs/s. X-ray observations over a 1.5 year time span combined with contemporaneous optical photometry show a decrease in the optical with no corresponding decrease in the X-ray. In contrast, similar observations of MCG 8-11-11 show a contemporaneous decrease in optical and X-ray fluxes. It is noted that the infrared and X-ray spectral slopes for these two objects are similar, with the optical being steeper by roughly one unit.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 89
    facet.materialart.
    Unknown
    The detection of a companion star to the Cepheid variable Eta Aquilae (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Ultraviolet spectra have been obtained with IUE of the classical Cepheid Eta Aquilae at several phases in the 7.18 day period. Significant ultraviolet emission is detected at wavelengths less than 1600 A, where little flux is expected from classical Cepheids. Furthermore, the emission at wavelengths less than about 1600 A does not vary with phase. Comparison with model atmosphere flux distributions shows that the nonvariable emission is consistent with the flux expected from a main-sequence companion star with an effective temperature of about 9500 K (A0 V). The observed ultraviolet flux and spectral type are used to compute a distance of 300 pc to the system, in agreement with the distance predicted using the period luminosity relation.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 90
    facet.materialart.
    Unknown
    On the time variability of Circinus X-1 - A comparison with Cygnus X-1 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The time variability and spectral characteristics obtained from Uhuru observations of Cir X-1 (4U 1515-56) are compared with observations of Cyg X-1 (4U 1956+35). It is found that Cir X-1 has a more variable spectrum (with perhaps a state over the 4 days spanned by the data), is less 'noisy', and has correlated fluctuations (as evidenced by the nonzero cross-correlation function between two energy bands) of shorter duration than those present in the shot noise of Cyg X-1.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 91
    facet.materialart.
    Unknown
    X-rays from RS Canum Venaticorum systems - A HEAO 1 survey and the development of a coronal model (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The paper presents HEAO 1 low-energy X-ray observations of 59 known or suspected RS CVn systems cited in the lists of Hall (1976), Eggen (1978), and the circulars of the Working Group on RS CVn systems of IAU Commission 42. The data are used to argue against the validity of the minimum flux coronal models. A coronal loop model is used to derive expressions for the loop parameters in terms of observable quantities, and find acceptable solutions for RS CVn systems. It is concluded that the difference between solar activity and that observed in RS CVn systems may be merely a matter of scale.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 92
    facet.materialart.
    Unknown
    Comments on stellar boundary cooling and the reality of supermetallicity (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The paper discusses the 'super-metal-rich' (SMR) stars and reexamines Peterson's analysis of the SMR prototype mu Leo (1978) with regard to a postulated error in continuum error. Model atmospheres are used to compute theoretical equivalent widths and to explore the sensitivity of these widths to metallicity, temperature, surface gravity, and microturbulence. It is shown that Peterson's results are sensitive to continuum placement, and that her data does not indicate that the temperature gradient is steeper in mu Leo than in normal giants. It is concluded that the SMR stars are very metal rich and are also somewhat boundary cooled, possibly due to high metallicity.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 93
    facet.materialart.
    Unknown
    Gamma rays from Penrose powered black holes in Centaurus A, 3C 273, and NGC 4151 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Gamma-ray observations of Cen A, 3C 273, and NGC 4151 are examined under the assumption that Penrose collision processes in the ergospheres of massive black holes power their nuclei. The observed sharp break in the MeV region of the NGC spectrum is attributed to Penrose Compton scattering, and the absence of an MeV break in the spectra of Cen A and 3C 273 implies Penrose pair production. Central black hole masses of tens of millions of solar masses for NGC 4151 and Cen A, and tens of billions of solar masses for 3C 273, are obtained. Attention is also given to accretion rate, the efficiency of accretion, QSOs and Seyferts.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 94
    facet.materialart.
    Unknown
    The plane of symmetry of interplanetary dust in the inner solar system (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Observations of the zodiacal light from the space probes Helios 1 and 2 between 1.0 and 0.3 AU show - superimposed on the general radial dependence - a systematic variation of brightness and brightness distribution with position in the orbit which is caused by the inclination of the symmetry plane of interplanetary dust with respect to the ecliptic. By suitable choice of the observing geometry, the inclination and the ascending node of the symmetry plane can be determined directly from the data without recourse to model calculations. The resulting values of i equals 3.0 plus or minus 0.3 deg, Omega equals 87 plus or minus 4 deg are not compatible with a concentration of interplanetary dust to the invariable plane of the solar system. The data support the simple view that the distribution of interplanetary dust in the inner solar system is characterized throughout by one plane of symmetry and suggest that this plane extends to at least 1 AU.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 82; 3, Fe; Feb. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 95
    facet.materialart.
    Unknown
    A laboratory study of magnesium-tetrabenz-porphyrin - Lack of agreement with diffuse interstellar bands (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The visible and infrared spectra and thermal behavior of the bis-pyridal-magnesium-tetrabenz-porphyrin molecule proposed as the carrier of the diffuse interstellar bands were measured. Of the six band coincidences reported by Johnson (1977), only one, 4430 A, occurs in these experiments. This coincidence requires a special environment, not likely to occur in interstellar space but the infrared spectrum does not support Johnson's vibrational scheme. These spectroscopic and thermal measurements contradict the hypothesis that this molecule causes the diffuse bands.
    Keywords: ASTROPHYSICS
    Type: Astrophysics and Space Science; 68; 1, Ma; Mar. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 96
    facet.materialart.
    Unknown
    Production of carbon, sulfur, and CS in Comet West (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Results from ultraviolet spectrographic observations of Comet West (1975n) in the 1620-3960 A wavelength range are presented. Objective grating imagery of the comet reveals for the first time emission from sulfur atoms and CS molecules as well as previously observed lines or bands in carbon atoms and CO(+), CO2(+) and OH molecules. Some evidence exists for emission in the C2 Mulliken bands and in the CO Cameron bands. On the basis of the observations, production rates of C (ground state), C(1D), S, and CS are inferred to be 3.8 x 10 to the 29th per sec, 4.4 x 10 to the 29th per sec, 1.7 x 10 to the 28th per sec, and greater than approximately 3.1 x 10 to the 27th per sec, respectively.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 97
    facet.materialart.
    Unknown
    The diffuse gamma-ray background in the Hoyle-Narlikar cosmology (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The paper analyzes the contributions of QSOs, BL-Lac objects and Seyfert galaxies to the diffuse gamma-ray background within the framework of the Hoyle-Narlikar theory. It is shown that the inconsistency reported in standard theory, namely that the evolutionary function needed to explain the gamma-ray data is very different from the one derived from the optical part of the spectrum, is no longer present. It is also shown that the contribution of a variable gravitational 'constant' to the expression for the diffuse background is the same as that of a density evolution function.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 92; 1-2,; Dec. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 98
    facet.materialart.
    Unknown
    Neutrino, gamma-ray, electron, and positron production in an ultrarelativistic plasma (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Neutrino, gamma-ray, electron and positron production resulting from inelastic proton-proton collisions in a highly relativistic plasma such as may exist in extragalactic radio or gamma-ray burst sources is examined. The source functions of primary (pions, kaons, and neutrons) and secondary (photons, electrons, positrons and neutrinos) products of relativistic nuclear collisions are computed for the cases of power law and Maxwellian relativistic proton distributions. It is shown that in plasma which is optically thin to interactions between the plasma and secondary gamma-rays, electrons and positrons, only a small fraction of the initial energy is emitted in the observable form of neutrinos and gamma rays. In an optically thick plasma on the other hand, most of the energy of the relativistic protons is found to be equally divided between gamma rays and neutrinos, although only the neutrinos may escape freely to be observed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 99
    facet.materialart.
    Unknown
    Dust-to-gas ratio in the outer regions of spiral galaxies (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Some spiral galaxies are surrounded by extended clouds of neutral hydrogen; if dust is associated with this gas, the dust should appear as a faint extended reflection nebula illuminated by the light from the entire galaxy. It is suggested that observations of the surface brightness of the outer regions of M83 and M101 could be worthwhile, since these two galaxies are bright and have extended surrounding gas clouds. Such studies would be of interest with regard to the possible presence of faint extended halos of stars around galaxies, the extent of the metallicity gradients in galaxies, and the value of the dust-to-gas ratio in quasar absorption-line systems.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 100
    facet.materialart.
    Unknown
    X-ray observations of Algol (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The Solid State Spectrometer on Einstein has been used to study Algol. Two observations six months apart were made, both including a primary optical eclipse. No corresponding X-ray eclipses were seen. During the second observation the source was flaring and was on the average a factor of three brighter. The spectrum on both occasions was consistent with a two-component thermal equilibrium model with temperatures of approximately 7.5 and 40 million degrees. Attempts to insert a third component indicate the temperature distribution to be bimodal. Models for the X-ray emission are discussed and it is suggested that it most likely originates from an active corona surrounding the K star.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    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...