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  • ASTROPHYSICS  (578)
  • LUNAR AND PLANETARY EXPLORATION  (552)
  • 1980-1984  (1,130)
  • 1925-1929
  • 1983  (1,130)
Collection
Years
  • 1980-1984  (1,130)
  • 1925-1929
Year
  • 1
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    Publication Date: 2011-08-18
    Description: Einstein solid-state-spectrometer (SSS) spectra are presented for the Crab Nebula, Cas A, SN 1006, the Tycho SNR, and the Kepler SNR. The history of X-ray observations of SNRs is reviewed; the SSS instrument is briefly characterized; a reduction technique which accounts for all background sources in the 0.5-4.5-keV band is applied; and the physical models of SNRs constructed to reproduce the refined spectra are discussed. The limitations of the modeling methods and the need for further observations, especially of localized regions, are indicated.
    Keywords: ASTROPHYSICS
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  • 2
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    Publication Date: 2011-08-18
    Description: New data indicate that red giants are surrounded by geometrically thick chromospheres of several stellar radii extent. Such chromospheres occur among stars which apparently lack coronae. Maintenance of this extended warm region may require non-compressional wave heating of a magnetic character, and this may provide a crucial clue to the mechanism of rapid mass loss from red giant stars.
    Keywords: ASTROPHYSICS
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  • 3
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    Publication Date: 2011-08-18
    Description: The Kitt Peak 2.1-m telescope and Intensified Image Dissector Scanner have been used to gather spectrophotometric data in the 3600-5200 A spectral region for five H II regions in the spiral galaxy NGC 628. The Pagel et al (1979) technique was then applied to determine the relative number abundances of O to H in each of the H II regions. An examination of the abundance values obtained as a function of the radial coordinate yields an O gradient of -0.05 + or - 0.03 dex/kpc.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 95; 986-988
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  • 4
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    Publication Date: 2011-08-18
    Description: Holberg's analysis of the Voyager Saturn photographs in reflected and transparent light, and occultation data of stars seen through the rings are discussed. A hyperfine structure with 10,000 ringlets can be explained by the Baxter-Thompson negative diffusion. This gives the ringlets a stability which makes it possible to interpret them as fossils which originated at cosmogonic times. It is shown that the bulk structure can be explained by the combined cosmogonic shadows of the satellites Mimas and Janus and the Shepherd satellites. This structure originated at the transition from the plasma phase to the planetesimal phase. The shadows are not simple void regions but exhibit a characteristic signature. Parts of the fine structure, explained by Holberg as resonances with satellites, are interpreted as cosmogonic shadow effects. However, there are a number of ringlets which can neither be explained by cosmogonic nor by resonance effects. Analysis of ring data can reconstruct the plasma-planetesimal transition with an accuracy of a few percent. Previously announced in STAR as N84-12013
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astrophysics and Space Science (ISSN 0004-640X); 97; 1, No; 79-94
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  • 5
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    Publication Date: 2011-08-18
    Description: The freezing of small Martian streams is modelled for a variety of climatic conditions, on the supposition that the Martian atmosphere may have been considerably thicker in the past, at the time of the formation of the valley networks. This model examines the energy balance at the upper and lower surfaces of ice on streams, in order to determine the rate at which ice thickens with time. Results indicate that freezing rates are not strongly dependent on atmospheric pressure, and, under windy conditions, dependence on atmospheric pressure is even weaker. It is noted that the main problem in valley formation is in initiating the flow. Groundwater seepage alone is inadequate, due to the difficulty of groundwater system replenishment.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 56; 476-495
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  • 6
    Publication Date: 2011-08-18
    Description: The existence of a possible influence of the large-scale structure of the universe on local physics is discussed. A particular realization of such an influence is discussed in terms of the behavior in time of atomic and gravitational clocks. Two natural categories of metric theories embodying a cosmic infuence exist. The first category has geodesic equations of motion in atomic units, while the second category has geodesic equations of motion in gravitational units. Equations of motion for test bodies are derived for both categories of theories in the appropriate parametrized post-Newtonian limit and are applied to the Solar System. Ranging data to the Viking lander on Mars are of sufficient precision to reveal (1) if such a cosmological influence exists at the level of Hubble's constant, and (2) which category of theories is appropriate for a descripton of the phenomenon.
    Keywords: ASTROPHYSICS
    Type: Physical Review D - Particles and Fields, 3rd Series (ISSN 0556-2821); 28; 1822-182
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  • 7
    Publication Date: 2011-08-18
    Description: Observations of large amplitude MHD waves upstream of Jupiter's bow shock are analyzed. The waves are found to be right circularly polarized in the solar wind frame, which suggests that they are propagating in the fast magnetosonic mode. A complete spectral and minimum variance eigenvalue analysis of the data was performed. The power spectrum of the magnetic fluctuations contains several peaks. The fluctuations at 2.3 MHz have a direction of minimum variance anti-parallel to the direction of the average magnetic field. Several harmonics at 6, 9, and 12 MHz are also present. The direction of minimum variance of these fluctuations lies at approximately 40 deg to the magnetic field. It is argued that these fluctuations are waves excited by protons reflected off the Jovian bow shock. The inferred speed of the reflected protons is about two times the solar wind speed in the solar wind frame. A linear instability analysis is presented that suggests an explanation for many of the observed features of the observations. The fluctuations apparently contain a significant fraction of magnetic energy that is linearly polarized and in the Alfven mode.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 9989-999
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  • 8
    Publication Date: 2011-08-18
    Description: NGC 7027 was observed with a multichannel grating spectrometer from 5.2 to 7.5 microns at a spectral resolving power of 120-200. Two new dust emission features are resolved at 5.62 and 6.95 microns, and for the first time the Ni II fine-structure line at 6.64 microns is detected. It is shown that a single molecular dust constituent might account for six of the nine observed dust features between 2 and 14 microns. The strength of the Ni II line indicates either that Ni is not depleted in the neutral gas, or that the line is formed at high density.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 274; 666-670
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  • 9
    Publication Date: 2011-08-18
    Description: Visual absolute magnitudes of classical Cepheids, metal-poor RR Lyrae stars and short-period type II Cepheids have been determined with very high precision by combining a large number of old and new astrophysical data. Five independent methods (four observational and one theoretical) have been successfully used: (1) secular and statistical parallaxes; (2) moving-group parallaxes; (3) cluster main-sequence fitting; (4) the Baade-Wesselink method and its modifications; and (5) light-curve and velocity-curve fitting (the theoretical method). With these five adopted methods, the zero point of the galactic and extragalactic distance scale can be set on a relatively firm and self-consistent basis. Classical Cepheids and RR Lyrae stars now provide essentially identical distances to nearby galaxies: the distance modulus to the Large Magellanic Cloud is 18.5 and to the Small Magellanic Cloud is 18.8, both with an uncertainty of 0.1. The distance to the center of our Galaxy is 8.6 plus or minus 0.5 kiloparsecs. The major uncertainty in these values lies in the correction for interstellar extinction.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 274; 20-30
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  • 10
    Publication Date: 2011-08-18
    Description: It is pointed out that the line profile coefficients for spontaneous and stimulated emission are identical in low-intensity radiation fields. In more intense radiation fields, however, the stimulated emission profiles in the radiative transfer equation and in the rate equations for the atomic level populations may differ from each other, owing to their different physical nature. A seeming discrepancy between the stimulated emission profiles of the usual semi-classical aproach and a recent quantum mechanical approach by Cooper et al. (1982), which should also be valid for intense 'broadband' fields, is discussed and shown to have negligible consequences for low-intensity radiation fields.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 127; 1, Oc; 224-226
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  • 11
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    Publication Date: 2011-08-18
    Description: Abundance and isotopic compositions are measured for the very volatile elements carbon, nitrogen and sulfur in 11 lunar rocks representing a wide spectrum of textures and compositions. Samples were combusted sequentially at three temperatures in order to remove terrestrial contaminants before melting the lunar rock and liberating lunar volatiles. The combustion results indicate very little terrestrial sulfur contamination, with sulfur contents correlated with the TiO2 contents of the basalts analyzed. Sulfur isotopic compositions are remarkably uniform and similar to the Canon Diablo meteorite standard. Nitrogen levels are found to be no greater than those obtained with procedural blanks, corresponding to abundances less than 0.1 microg/g. Stable nitrogen isotope measurements indicate a spallogenic N-15 production rate of 4.1 x 10 to the -6th microg N-15/g sample/million years, in agreement with previous estimates. No indigenous carbon in excess of procedural blank levels of about 0.7 microg/g is found in lunar basalts. Levels of 1 to 5 microg/g found in highland rocks may derive from meteoritic or terrestrial sources. The average measured spallogenic C-13 production rate is 4.1 x 10 to the -6th microg C-13/g sample/million years.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 47; 1769-178
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  • 12
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    Publication Date: 2011-08-18
    Description: Observational evidence for Baryon symmetric (matter/antimatter) cosmology and future observational tests are reviewed. The most significant consequences of Baryon symmetric cosmology lie in the prediction of an observable cosmic background of gamma radiation from the decay of Pi(O)-mesons produced in nucleon-antinucleon annihilations. Equations for the prediction of the gamma ray background spectrum for the case of high redshifts are presented. The theoretical and observational plots of the background spectrum are shown to be in good agreement. Measurements of cosmic ray antiprotons and the use of high energy neutrino astronomy to look for antimatter elsewhere in the universe are also addressed. Previously announced in STAR as N83-10996
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  • 13
    Publication Date: 2011-08-18
    Description: The flux of energetic protons in Saturn's inner magnetosphere was observed in two channels from 48 to 63 and 63 to 160 MeV. Absorption features due to the G ring and the satellites Enceladus and Mimas were easily identifiable. The flux observed in the absorption slot of Mimas can be maintained by the decay of a cosmic ray albedo neutron flux of 0.007/sq cm/s/sr. This flux is entirely consistent with calculations of the neutron flux produced by galactic cosmic ray interactions with the rings of Saturn. The omnidirectional proton flux of 0.0082/sq cm/s at 2.734 R sub s requires a residence time of 30 years. Both the residence time and the energy spectrum are comparable to those found in the inner radiation belt of the Earth. The angular distribution is nearly isotropic in the Mimas slot and beyond 4R sub s. Otherwise the pitch angle distribution is pancake and is approximated by sin(n)theta with n in the range 2 to 7. This distribution is consistent with an isotropic neutron source in the ring plane. Previously announced in STAR as N83-22084
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 8923-893
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  • 14
    Publication Date: 2011-08-18
    Description: The low energy plasma electron environment within Saturn's magnetosphere was surveyed by the Plasma Science Experiment (PLS) during the Voyager encounters with Saturn. Over the full energy range of the PLS instrument (10 eV to 6 keV) the electron distribution functions are clearly non-Maxwellian in character; they are composed of a cold (thermal) component with Maxwellian shape and a hot (suprathermal) non-Maxwellian component. A large scale positive radial gradient in electron temperature is observed, increasing from less than 1 eV in the inner magnetosphere to as high as 800 eV in the outer magnetosphere. Three fundamentally different plasma regimes were identified from the measurements: (1) the hot outer magnetosphere, (2) the extended plasma sheet, and (3) the inner plasma torus. Previously announced in STAR as N83-34872
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 8847-887
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  • 15
    Publication Date: 2011-08-18
    Description: The planetary magnetic field of Saturn has been studied by the spacecraft Pioneer 11 in 1979, Voyager 1 in 1980, and Voyager 2 in 1981. The field is found to be primarily dipolar and axially coincident with the rotation axis, but with significant quadrupole and octupole moments. The harmonic terms are g1(0) = 21535 nT, g2(0) = 1642 nT, and g3(0) = 2743 nT. This model field, Z3, in conjunction with a model for an equatorial ring current, represents very precisely the in situ magnetic-field measurements and data on charged-particle absorption by satellites and rings within 8 Saturn radii of the planet. However, this axisymmetric model fails to explain the periodic modulation of Saturn's kilometric radiation or Saturn's electrostatic discharges. This enigma of Saturn's magnetosphere remains unsolved in spite of extensive reconsideration of all available data bearing on this issue.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 8771-877
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  • 16
    Publication Date: 2011-08-18
    Description: Voyager 2 photometric and polarimetric data are reduced and tabulated, with spatially resolved limb-to-terminator scans across Saturn's equatorial zone providing information on the altitude distribution of UV-absorbing hazes, together with the phase function and polarizing properties of stratospheric and tropospheric aerosols. It is found that the UV photometry and polarimetry are best fit by Rayleigh's phase matrix. A stratospheric haze of small particles is allowed as long as the optical depth is near unity or less, and the center of the haze layer is in the 30 to 70 mbar region. The altitudes presently derived for three latitudes agree with those obtained by ground-based methane band studies and analyses from Pioneer 11. A high altitude absorber is abundant in the polar regions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 8679-869
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  • 17
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    Publication Date: 2011-08-18
    Description: Attention is given to semidetached binaries of the Algol type and to related interacting systems, such as Beta Lyrae and the W Serpentis stars. A brief description is given of observational problems. The basic properties of the Algol variables are satisfactorily explained by means of evolutionary models that assume considerable mass transfer between the components. It is pointed out that ultraviolet spectra obtained with the IUE satellite corroborate the view that the present subgiant secondary component was initially the more massive star and that it has been stripped of a large fraction of its mass so that the deep layers affected by CNO processing are now denuded. It is believed that the present-day 'classical' Algols must have undergone a phase of rapid mass transfer in the past and that Beta Lyrae and the W Serpentis stars are probably closer to that stage than ordinary Algols. Around the accreting star a complex structure is formed, and an induced stellar wind may blow a large part of the transferred matter out of the system.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society of Canada, Journal (ISSN 0035-872X); 77; 283-304
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  • 18
    Publication Date: 2011-08-18
    Description: Small-scale impact craters (5-7 mm in diameter) were produced with a light gas gun in high purity Au and Cu targets using soda lime glass (SL) and man-made basalt glass (BG) as projectiles. Maximum impact velocity was 6.4 km/s resulting in peak pressures of approximately 120-150 GPa. Copious amounts of projectile melts are preserved as thin glass liners draping the entire crater cavity; some of this liner may be lost by spallation, however. SEM investigations reveal complex surface textures including multistage flow phenomena and distinct temporal deposition sequences of small droplets. Inasmuch as some of the melts were generated at peak pressures greater than 120 GPa, these glasses represent the most severely shocked silicates recovered from laboratory experiments to date. Major element analyses reveal partial loss of alkalis; Na2O loss of 10-15 percent is observed, while K2O loss may be as high as 30-50 percent. Although the observed volatile loss in these projectile melts is significant, it still remains uncertain whether target melts produced on planetary surfaces are severely fractionated by selective volatilization processes.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 88; B353-B36
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  • 19
    Publication Date: 2011-08-18
    Description: Models for the production of agglutinates are developed that can be applied to the lunar surface or to any planetary or asteroidal body lacking an atmosphere. Models are developed using rate equations for progressively more complex situations and range from Model 1, which is a simple linear increase of agglutinate content with time, to Model 4, which includes provision for recycling of existing agglutinates and replenishment and burial of exposed soil. Model 4 has some aspects of a steady state because, depending on the rate constants, agglutinate content may be limited to an intermediate value, even for long exposure times. In an extreme case, agglutinate content may be limited to a value near zero. These models predict that agglutinates should be low in abundance in areas of thin regolith, such as the Lunokhod-2 site on the moon, and on asteroids. The models may also help explain the apparent low agglutinate abundances of lunar regolith breccias and meteorite regolith breccias.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 88; B193-B19
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  • 20
    Publication Date: 2011-08-18
    Description: Texturally pristine clasts preserve primary petrographic relationships and mineral compositions, yielding insights into igneous processes of the early lunar crust that cannot be gained from highly shocked and brecciated 'chemically pristine' samples. The use of texture as a prime criterion allows for expansion of the data base derived solely from chemical criteria, and provides complementary data. Texturally pristine clasts from the Apollo 14 site studied here include anorthosite, troctolites, gabbronorites, and basalts. Alkali anorthosites are plagioclase orthocumulates and may form by flotation in Mg-suite plutons. Ferroan anorthosite was cataclastically deformed and metamorphosed to granulite facies. Troctolites include both 01 + Plg and 01 + En + Plg cumulates. Major and trace element analyses of two troctolites reveal 'eastern' geochemical affinities that contrast other 'western' troctolites. Gabbronorites are Pig + Plg + or - Sp cumulates whose parent magmas may range from high-Al to intermediate-Ti mare basalt. At least three varieties of mare basalt are found at Apollo 14: high-Al, low-Ti; low-Al, intermediate-Ti; and low-Al, Ti VHK basalt. VHK (Very High Potassium) basalt is a new variety indigenous to Apollo 14.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 88; B177-B19
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  • 21
    Publication Date: 2011-08-18
    Description: Parker's (1980) nonlinear inverse theory for the electromagnetic sounding problem is converted to a form suitable for analysis of lunar day-side transfer function data by: (1) transforming the solution in plane geometry to that in spherical geometry; and (2) transforming the theoretical lunar transfer function in the dipole limit to an apparent resistivity function. The theory is applied to the revised lunar transfer function data set of Hood et al. (1982), which extends in frequency from 10 to the -5th to 10 to the -3rd Hz. On the assumption that an iron-rich lunar core, whether molten or solid, can be represented by a perfect conductor at the minimum sampled frequency, an upper bound of 435 km on the maximum radius of such a core is calculated. This bound is somewhat larger than values of 360-375 km previously estimated from the same data set via forward model calculations because the prior work did not consider all possible mantle conductivity functions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 88; B97-B102
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  • 22
    Publication Date: 2011-08-18
    Description: Diurnal solar heating of Venus' surface produces variable temperatures, winds, and pressure gradients within a shallow layer at the bottom of the atmosphere. The corresponding asymmetric mass distribution experiences a tidal torque tending to maintain Venus' slow retrograde rotation. It is shown that including viscosity in the boundary layer does not materially affect the balance of torques. On the other hand, friction between the air and ground can reduce the predicted wind speeds from about 5 to about 1 m/sec in the lower atmosphere, more consistent with the observations from Venus landers and descent probes. Implications for aeolian activity on Venus' surface and for future missions are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 56; 165-175
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  • 23
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    Publication Date: 2011-08-18
    Description: The problem posed by the existence of a negative buoyancy work region at the top of cellular type convection in a deeply stratified superadiabatic layer (Massaguer and Zahn, 1980) is addressed. It is approached by studying two-dimensional cellular compressible convection with different physical parameters. The results suggest that a large viscosity, together with density stratification, is responsible for the buoyancy reversal. The numerical results obtained are analyzed. It is pointed out, however, that in an astrophysical situation a fluid involved in convection will generally have very small viscosity. It is therefore thought unlikely that buoyancy reversal occurs in this way.
    Keywords: ASTROPHYSICS
    Type: Astrophysics and Space Science (ISSN 0004-640X); 95; 2, Se; 453-457
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  • 24
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    Publication Date: 2011-08-18
    Description: Duley (1982) has proposed that many of the diffuse interstellar bands in the wavelength interval 542-677 nm arise from vibronic transitions of Cr (3+) ions in MgO grains. No explanation has been offered for the fact that as many as 85 of the possible 108 transitions of this system have not been observed in the interstellar medium. Moreover, the relative intensities of the diffuse bands which are observed appear to be inconsistent with their assignment. It is therefore concluded that this model is not consistent with the observations.
    Keywords: ASTROPHYSICS
    Type: Astrophysics and Space Science (ISSN 0004-640X); 95; 1, Se
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  • 25
    Publication Date: 2011-08-18
    Description: The plausibility of relatively pure diatomic oxide crystals forming in the expanding atmospheres of cool stars is commented on, and the likelihood of SiO grains condensing is discussed on the basis of laboratory nucleation experiments. Results of annealing experiments are used to consider the further evolution of silicon oxide and silicate grains. The evidence shows that SiO solids form only when SiO condenses directly onto surfaces, and that the probability of pure crystalline SiO grains forming is rather small.
    Keywords: ASTROPHYSICS
    Type: Astrophysics and Space Science (ISSN 0004-640X); 95; 1, Se
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  • 26
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    Publication Date: 2011-08-18
    Description: Newly defined characteristics of planetary nebulae (PN) derived from analysis of a photometric survey of 57 PN are reported. The data were combined with measurements of 27 other PN made since 1918 and were found to indicate core masses ranging from 0.55-1.0 solar mass. N/O elemental abundance ratios observed were correlated with the planetary nuclei masses, and were in direct proportion. IUE data on PN that overlapped a large part of the survey indicated that the PN in the galactic disk are more massive than PN in the halo. It is suggested that PN evolve into white dwarfs, a hypothesis supported by astrometric solutions for three nearby visual binaries featuring white dwarfs with well-determined masses. It is noted, however, that PN with masses exceeding one solar mass have been sighted in the Magellanic Clouds.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 305; 670
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  • 27
    Publication Date: 2011-08-18
    Description: In 1979-1981, the three USA spacecraft Pioneer 11 and Voyagers 1 and 2 discovered and explored the magnetosphere of Saturn to the limited extent possible on flyby trajectories. Considerable variation in the locations of the bow shock (BS) and magnetopause (MP) surfaces were observed in association with variable solar wind conditions and, during the Voyager 2 encounter, possible immersion in Jupiter's distant magnetic tail. The limited number of BS and MP crossings were concentrated near the subsolar region and the dawn terminator, and that fact, together with the temporal variability, makes it difficult to assess the three dimensional shape of the sunward magnetospheric boundary. The combined BS and MP crossing positions from the three spacecraft yield an average BS-to-MP stagnation point distance ratio of 1.29 +/- 0.10. This is near the 1.33 value for the Earth's magnetosphere, implying a similar sunward shape at Saturn. Study of the structure and dynamical behavior of the outer magnetosphere, both in the sunward hemisphere and the magnetotail region using combined plasma and magnetic field data, suggest that Saturn's magnetosphere is more similar to that of Earth than that of Jupiter. Previously announced in STAR as N83-30346
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 8791-880
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  • 28
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    Publication Date: 2011-08-18
    Description: Two new possible planetary nebulae have been identified using the Parker, Gull, and Kirshner (1979) emission-line survey of the galactic plane. Both objects exhibit very strong forbidden O III lambda 5007 line emission, a symmetrical morphology, and a faint blue central star.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 95; 614-618
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  • 29
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    Publication Date: 2011-08-18
    Description: Tentative conclusions about the origins of channels and valleys on Mars based on the consensus of investigators who have studied the problem are presented. The morphology of outflow channels is described in detail, and the morphology, distribution, and genesis of Martian valleys are addressed. Secondary modification of channels and valleys by mass-wasting phenomena, eolian processes, cratering, and mantling by lava flows is discussed. The physics of the flows needed to account for the immense volumes of Martian outflow channels is considered in detail, including the possible influence of debris flows and mudflows, glaciers, and ice sheets. It is concluded that Mars once probably possessed an atmosphere with higher temperatures and pressures than at present which played an essential role in an active hydrological cycle.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geological Society of America, Bulletin (ISSN 0016-7606); 94; 1035-105
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  • 30
    Publication Date: 2011-08-18
    Description: The Mutch Memorial Station (Viking Lander 1) on Mars acquired imaging and meteorological data over a period of 2245 martian days (3.3 martian years). This article discusses the deposition and erosion of thin deposits (ten to hundreds of micrometers) of bright red dust associated with global dust storms, and the removal of centimeter amounts of material in selected areas during a dust storm late in the third winter. Atmospheric pressure data acquired during the period of intense erosion imply that baroclinic disturbances and strong diurnal solar tidal heating combined to produce strong winds. Erosion occurred principally in areas where soil cohesion was reduced by earlier surface sampler activities. Except for redistribution of thin layers of materials, the surface appears to be remarkably stable, perhaps because of cohension of the undisturbed surface material.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 222; 463-468
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  • 31
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    Publication Date: 2011-08-18
    Description: First IUE spectrograms of the peculiar emission-line object M1-2 (= VV 8) are presented. In the wavelength region 1150-3200 A this object is characterized by emission lines superposed on a moderately strong continuum. Some ultraviolet and optical properties of M1-2 are discussed in the context of symbiotic stars and protoplanetary and planetary nebulae. An E(B-V) extinction of 0.37 mag is obtained from the ratio of the He II flux at 1640 and 4686 A and is compared with values derived from other parameters. The ultraviolet observations suggest that M1-2 is a young, high-density planetary nebula of excitation class 5 or 6 with characteristics similar to IC 4997.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 275; 628-635
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  • 32
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    Publication Date: 2011-08-18
    Description: Obsrvations and theoretical investigations of the Gum nebula (GN) since about 1971 are reviewed. Direct observations of the GN, the Vela X supernova remnant (SNR), the Vela pulsar, and other stars in or near the GN are discussed with those of related phenomena such as the radio loops and known SNRs; the emphasis is on studies of the interstellar absorption lines, the evidence for hot gas in the GN, and the extended diffuse emission. The four basic models proposed for the GN are considered: a fossil Stromgren sphere, an old SNR, an H II region, or a superbubble. The GN physical parameters predicted by each model are listed in a table and compared. A minimum explanation which attributes the 36 x 36-deg filamentary structure and the 125-pc radius structure to the action of the stellar winds from Zeta Pup and Gamma-2 Vel (and perhaps the effect of a Vel X supernova explosion 20,000 years ago) is found most appropriate, at least until the questions of the net expansion rate of the GN (about 20 km/sec or about zero?) and the existence of the diffuse emission beyond the filamentary structure are resolved by observations.
    Keywords: ASTROPHYSICS
    Type: Comments on Modern Physics, Part C - Comments on Astrophysics (ISSN 0146-2970); 10; 1-14
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  • 33
    Publication Date: 2011-08-18
    Description: Previous work on electron heating mechanisms operating at the supercritical earth's bow shock is extended to the generally lower Mach number interplanetary shocks. This is done by studying electron velocity distributions observed both upstream and downstream of interplanetary shocks observed by ISEE 3 between August 1978 and December 1979. It is found that perpendicular heating accompanied by little or no parallel heating occurs at the weaker shocks but that parallel heating is dominant for the stronger shocks. When perpendicular heating is dominant, downstream velocity distributions are for the most part Gaussian at low energies (core) and Lorentzian at high energies (halo). When parallel heating is dominant, however, these distributions are flat-topped at low energies, having power law extensions to higher energies. At the weaker shocks, the observations are consistent with electron heating resulting from conservation of the magnetic moment, whereas at the stronger shocks the heating is quite similar to that observed at the earth's bow shock.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 9949-995
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  • 34
    Publication Date: 2011-08-18
    Description: Preliminary inspection of archival high-dispersion ultraviolet spectra obtained by the International Ultraviolet Explorer reveal sharp shortward-shifted features in the spectra of O subdwarfs. In three examples presented here, BD + 75.325 deg, HD 128220 B, and BD + 28.4211 deg, stable, multiple, discrete shortward-shifted components of the N V, C IV, and Si IV resonance doublets are seen. The available data suggest that some of these features are persistent, being relatively stable in velocity and intensity over at least 9 months. It is tentatively suggested that the mechanism, or mechanisms, producing these discrete features operates universally in hot stars, from luminous O and B stars down through the O subdwarfs to include the hot white dwarfs. If true, this has important ramifications for current knowledge of mass loss in hot stars.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 274; L87-L91
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  • 35
    Publication Date: 2011-08-18
    Description: Ultraviolet images of the SAB(s)c I-II galaxy M83 (NGC 5236) obtained with a rocketborne telescope in broad bandpasses centered at 1540 A and 2360 A show a bright resolved nuclear source which accounts for approximately 20 percent of the flux of the galaxy in both bandpasses. Low-resolution International Ultraviolet Explorer spectra of this source reveal an energy distribution similar to that of the starburst nucleus of NGC 7714. Strong blueshifted absorption lines can be interpreted as evidence for a nuclear wind powered by supernovae. Observations from UV, X-ray, optical, and far-infrared bandpasses are consistent with a starburst approximately one-sixth as strong as that in M82. A scaling of the M82 models of Rieke et al. (1980) predicts that the nucleus of M83 contains 10 to the 6th - 3 x 10 to the 7th solar masses in young stars and has a supernova rate of approximately 0.01 per yr.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 274; L53-L56
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  • 36
    Publication Date: 2011-08-18
    Description: A comparison is presented of the black hole candidates LMC X-3 and Cygnus X-1 based on Einstein observations of LMC X-3 with the monitor proportional counter. A spectral analysis shows LMC X-3 to be more like the typical bright galactic X-ray source than Cygnus X-1. A search for periodic pulsations over a period range from 0.2 ms to over 1000 s set upper limits at the 90 percent confidence level of the order of 10 percent. An analysis of the aperiodic variability of LMC X-3 shows none of the shot noise behavior characteristic of Cygnus X-1. The absence of distinctive X-ray properties common to both sources suggests that the identification of black hole candidates on the basis of X-ray properties similar to Cygnus X-1 (or LMC X-3) is not reliable.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 274; L65-L69
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  • 37
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    Publication Date: 2011-08-18
    Description: The Kalnajs (1972, 1976) Omega models of global mass and velocity distributions are employed in the present two-dimensional N-body simulation, which allows for a spectrum of particle masses, stellar explosions, explosion remnant interactions with an interstellar medium, and the creation of new stars from the gas. Two sequences of runs using the Omega values of 0.8 and 0.9 examine the separate and combined effects of particle mass distribution, the gravitational influence of an interstellar gas distribution on the N-body particles, and stellar evolution, allowing for stellar explosions and star formation from the gas. It is found that both Omega values' nonequilibrium results dramatically change when evolution is allowed to occur. These results call for more realistic coupled N-body and evolution simulations in order to improve the understanding of disk galaxy evolution.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 274; 595-610
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  • 38
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    Publication Date: 2011-08-18
    Description: An assessment is made of the extent to which the study of the isotropy of the X-ray sky has contributed to the present understanding of the structure of the universe at moderate redshifts. It is, of course, the anisotropic character of the sky flux that is valuable in this context. Although it is not currently possible to undertake measurements with the precision and small solid angles that are typically achieved in the microwave range, the comparatively crude limits from the X-ray fluctuations place limits on the largest scale structure of the universe. After indicating the nature of measurements made, with the HEAO 1 A-2 experiment, of the X-ray sky and its anisotropies, it is shown how these place limits on the origin of the X-ray sky and on any large scale structure of the universe.
    Keywords: ASTROPHYSICS
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  • 39
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    Publication Date: 2011-08-18
    Description: The problem of stability of asteroids is treated from the point of view of Hill's stability-concept and using Lyapunov's Characteristic Numbers. The quantitative measure of stability (S) introduced earlier is evaluated for over 300 asteroids and a surprisingly simple relation is established between the semi-major axes of some of the asteroids' orbits and S. A detailed analysis is presented of the Lyapunov Characteristic Numbers for two minor planets and the time-variation of these numbers is discussed. The technology of capture of asteroids is vitally dependent on their orbital stability, therefore, these two problems, i.e., capture and stability, are closely related. In fact, some predictable instabilities may be properly utilized to capture and/or change asteroidal orbits to accomplish collisions with the Earth.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Sao Paulo Univ. The Motion of Planets and Nat. and Artificial Satellites, Volume 2; p 39-46
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  • 40
    Publication Date: 2011-08-19
    Description: Sr and Nd isotopic analysis of five Yamato polymict eucrites indicate that these samples formed at about 4.6 Ga ago with initial Sr and Nd ratios essentially the same as the analyzed non-Antarctic eucrites. The Yamato eucrites have Sr, Sm, and Nd concentrations that consistently lie among the highest found in eucritic samples. This characteristic identifies these Yamato samples as a closely related group. Comparisons between these Yamato samples and other Antarctic polymict eucrites clearly estabishes that they all share some characteristic trace element features. Comparisons of Antarctic polymict eucrites with non-Antarctic ordinary eucrites reveal consistent differences. The most obvious is an enrichment of Rb in the polymict eucrites. These comparisons suggest that the Antarctic polymict eucrites belong to a single large family of material that is itself fairly diverse and distinct from the non-Antarctic eucrites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: National Institute of Polar Research, Memoirs, Special Issue (ISSN 0386-0744); 30, D
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  • 41
    Publication Date: 2011-08-19
    Description: It is noted that it is helpful to divide the atmosphere of an early-type star into two parts: a photosphere and a mantle. The photosphere can be modeled satisfactorily by normal model-atmosphere procedures. When modeling the mantle, one must take account of the deposition of nonradiative heat and momentum and one should recognize that the mantles of hot stars do not appear to be uniform or spherically symmetric. Five areas of discrepancy between classical theory and observation are noted and a possible way of modeling the mantles of early-type stars is outlined. The model consists of arcades of magnetic loops which form helmet-type structures in the equatorial band of the star, and of coronal-hole-type structures emmanating from weak unipolar regions which are chiefly distributed at polar latitudes.
    Keywords: ASTROPHYSICS
    Type: Hvar Observatory, Bulletin (ISSN 0351-2651); 7; 1, 19
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  • 42
    Publication Date: 2011-08-19
    Description: Information about the effective temperatures, radii, and masses of O-type stars is presented. It is argued that rapid variations in the amount of light from O stars and the spectral distribution are a result chiefly of changes which occur in the envelope of the star. The stability of the photospheric layers of O stars against convection is reviewed and it is noted that late O stars and early B stars have a convection zone in the deeper parts of the photosphere. This convection zone is due to the second ionization of helium. Evidence is reviewed that most of the line-profile changes seen for O stars are generated by changes in the physical state of the mantle of the star, that is of the outer atmosphere where the deposition of non-radiative energy and momentum controls the physical state of the atmosphere. The physical state of the mantle may change in response to changes in the upper envelope of a star with a different time constant than the photosphere does.
    Keywords: ASTROPHYSICS
    Type: Hvar Observatory, Bulletin (ISSN 0351-2651); 7; 1, 19; 1-15; Di
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  • 43
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    Publication Date: 2011-08-19
    Description: Analysis of current experimental results concerned with the kinetic constraints on chondrule formation showed that the major physical properties of chondrules could have been produced by direct condensation of metastable liquid silicates droplets from a hot gas in the primordial nebula. It is argued that such a condensation process would have to be followed by crystallization, accretion, and partial comminution of the droplets. The chemical mechanisms driving this process are described, including: nucleation constraints on comminution and crystallization; slow transformations and chemical reactions in chain silicates; and the slow diffusion of ions. It is shown that the physical mechanisms for chondrule condensation are applicable to a broad spectrum of chondrule sources.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 44
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    Publication Date: 2011-08-19
    Description: Recent studies using data from Voyagers 1 and 2 to correlate variations in the Saturn kilometric radiation (SKR) with changes in solar-wind properties are summarized and illustrated with graphs. Best SKR correlations have been obtained with the solar-wind ram pressure and the related kinetic energy flux. It is pointed out that the related phenomenon on earth, the auroral kilometric radiation, occurs mainly in the nightside auroral region (as opposed to the dayside cleft region for SKR) and is best correlated with solar-wind velocity and inverted-V electron-precipitation events, implying a different stimulation process. The evidence for solar-wind control of the non-Io-related decametric radiation of Jupiter is also reviewed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Oesterreichische Akademie der Wissenschaften, mathematisch-naturwissenschaftliche Klasse, Sitzungsberichte, Abteilung 2 (ISSN 0723-9319); 192; 8-10,
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  • 45
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    Publication Date: 2011-08-18
    Description: The development of a numerical model for the dust environment near a comet is described. The major components of the model are a simple treatment of the acceleration of the dust by the gas outflow from an isothermal icy nucleus, a detailed treatment of the dust particle trajectories controlled by solar gravity and radiation pressure, including the formation of the dust envelope and tail, and a simple treatment of the radiation from the dust in the visible and thermal infrared. The results of recent comet observations are used to estimate parameter values for the model, including dust-to-gas ratios by light and by mass, the distribution of dust and gas emission on the nuclear surface, the distributions of dust particle size, density, mass, and radiative properties, and other quantities. Gas and dust production rates as functions of time are derived from observed light curves using the simple photometric theory. Sample results are presented for the dust concentration, flux and fluence along the trajectory of a spacecraft which flies by Comet P/Halley in 1986.
    Keywords: ASTROPHYSICS
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  • 46
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    Publication Date: 2011-08-18
    Description: A simple cometary outer ion coma model is constructed by adopting published results from numerical MHD computations. The ion composition and density distributions so derived are used to highlight some of the basic features of cometary plasma flows and the need for cometary ion observations with absolute brightness calibration.
    Keywords: ASTROPHYSICS
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  • 47
    Publication Date: 2011-08-18
    Keywords: ASTROPHYSICS
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  • 48
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    Publication Date: 2011-08-18
    Description: Observational data on the thermal emission from cometary dust grains and theoretical models constructed to explain them are reviewed. Consideration is given to grain temperature, the size distribution of the grains, thermal-emission models, the silicate component, dust-grain albedo, and icy grains; model predictions and observations are compared in graphs. It is pointed out that no unambiguous detection of icy grains has been achieved, probably because these grains are vaporized within a few hundred km of the nucleus when the comet is within 2.5 AU of the sun.
    Keywords: ASTROPHYSICS
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  • 49
    Publication Date: 2011-08-18
    Description: The response to a gravitational wave of two free masses whose relative motion is monitored with an electromagnetic tracking signal is derived. The results indicate a two-feature signature in one-way data and a three-feature signature in two-way data. The effect is applied to gravitational wave experiments using laser interferometers, spacecraft Doppler tracking, planetary ranging, and pulsar timing analysis. Actual results are presented from spacecraft Doppler experiments and from pulsar timing data analysis, with new upper limits being set on a possible cosmic gravitational wave background via the pulsar data.
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  • 50
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    Publication Date: 2011-08-18
    Description: Infrared observations of relatively isolated giant H II complexes in the LMC and the spiral arms of M33 and M101 are discussed, and complexes which extend over several kiloparsecs near the galactic centers are examined. The 30 Doradus nebula is emphasized, showing the variation of the 50-100 micron color temperature with position in that object. Ten-micron scans through the nucleus of NGC 1097 are compared to a visual photograph, showing the enhanced infrared emission which occurs at the nucleus and at the ring of H II regions about 1 kpc from the nucleus.
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  • 51
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    Publication Date: 2011-08-18
    Description: A bibliography of articles entered into the data base at the Lunar and Planetary Institute Library from November 1982 through January 1983 is presented. An abstract of each article is given. The subjects covered by the articles include: the motion of the moon and dynamics of the earth-moon system: shape and gravity field of the moon; the physical structure of the moon, its thermal and stress history; the morphology of the lunar surface, the origin and stratigraphy of lunar formations, and mapping of the moon; the chemical composition of the moon, lunar petrology, mineralogy, and crystallography; electromagnetic properties of the moon; the planets; and other objects, including asteroids, comets, meteorites, and cosmic dust.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Moon and the Planets (ISSN 0165-0807); 29; 237-327
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  • 52
    Publication Date: 2011-08-18
    Description: Saturn electrostatic discharges (SED) monitored by the Voyager 1 were investigated to determine the source of the phenomena. Consideration has been given to two sources: the atmosphere at equatorial latitudes, where the cloud-top wind velocities correspond to the Saturn 10 hr 10 min rotation period; and the rings at 1.8 Saturn radius. The data were analyzed in terms of time and frequency, revealing a time-varying frequency, few detectable discharges outside of a low threshold, and the appearances and disappearances of the SED with no correlation with frequency. The periodicity of the SED episodes indicated that the source was occulted between revolutions, which ruled out the ring source. The SED signals were only detected on the dayside, suggesting the signals propagated through the dayside ionosphere. Diurnal variations in the ion densities could prohibit the signals from escaping on the nightside, a factor supported by detection of low frequency SED only during close passage of the Voyager. Ray tracing experiments have demonstrated that storm sources have emissions observable with the storm on the limb at the observed 30-40 MHz interval.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 303; May 5
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  • 53
    Publication Date: 2011-08-18
    Description: When seen at frost cap minimum, Martian north polar erg dunes north of 80 deg N record east winds, while those south of that latitude record west winds. Many of the transverse dunes are considered to be reversing dunes, and dunes in the two fields may have reversed at least once during the lifetime of the Viking Orbiters. It is proposed that the average polar winds are strong, off-pole northwest winds in the fall, moderate west winds in winter, latitude-dependent weak-to-strong off-pole northeast winds in spring, and weak west winds in summer, as has been largely confirmed by Viking images of near polar clouds. Over millenia, the combination of reversing west and east winds could produce the biomodal distributions of dune orientations observed at the north pole.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 55; Sept
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  • 54
    Publication Date: 2011-08-18
    Description: In the upper troposphere and lower stratosphere of Jupiter, translationally hot H atoms are produced in the photolysis of ammonia, phospine, and acetylene which react with methane to form methyl radicals. The latter combine with NH2 to form methylamine. It is presently shown that the combined production of methylamine and subsequent photolysis to HCN is unlikely to account for the HCN observed near Jupiter's tropopause. The recommendation of NH2 and C2H3 radicals to yield C2H5N, followed by photolysis to HCN, is the preferred path. An upper limit column density on CH3PH2 is estimated to be about 10 to the 13th/sq cm, as compared to 10 to the 15th/sq cm for CH3NH2.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 55; Sept
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  • 55
    Publication Date: 2011-08-18
    Description: The NLTE radiative transfer problem is solved to obtain the 00 deg 1 vibrational state population. This model successfully reproduces the existing center-to-limb observations, although higher spatial resolution observations are needed for a definitive test. The model also predicts total fluxes which are close to the observed values. The strength of the emission is predicted to be closely related to the instantaneous near-IR solar heating rate.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 55; Sept
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  • 56
    Publication Date: 2011-08-18
    Description: Observations of the total flux and center to limb dependence of the nonthermal emission occurring in the cores of the 9.4 and 10.4 micrometers CO2 bands on Mars are compared to a theoretical model based on this mechanism. The model successfully reproduces the observed center to limb dependence of this emission, to within the limits imposed by the spatial resolution of the observations of Mars and Venus. The observed flux from Mars agrees closely with the prediction of the model; the flux observed from Venus is 74 percent of the flux predicted by the model. This emission is used to obtain the kinetic temperatures of the Martian and Venusian mesospheres. For Mars near 70 km altitude, a rotational temperature analysis using five lines gives T = 135 + or - 20 K. The frequency width of the emission is also analyzed to derive a temperature of 126 + or - 6 K. In the case of the Venusian mesosphere near 109 km, the frequency width of the emission gives T = 204 + or - 10 K.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 55; Sept
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  • 57
    Publication Date: 2011-08-18
    Description: The pre-main sequence X-ray emitting stars observed in molecular clouds appear to provide the bulk of the ionization. Newly forming stars therefore control the coupling of the magnetic field to the cloud. Since this coupling itself is believed to be responsible for the rate of cloud collapse, it is suggested that there is a natural feedback mechanism, involving observed X-rays, which is capable of regulating molecular cloud evolution and the rate of star formation.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 272; Sept. 15
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  • 58
    Publication Date: 2011-08-18
    Description: Observed velocity-size correlations are reexamined in the light of an improved theory of turbulent energy cascade that is developed. It is shown that observed velocity-size correlations cannot be compared with the Kolmogorov law, which is based on incompressible turbulent flow. The fact that the log v-log(l/rho) scaling law (v the turbulent velocity, l the associated region size, and rho the fluid density) predicted for compressible energy cascade is always steeper than that observed in molecular clouds indicates the injection rather than the dissipation of mechanical energy at smaller scales of motion. It is also shown that the concept of strict energy cascade may not be generally applicable in the interstellar medium. The agreement between theory and observation turns out to be best for small cool clouds and cloud cores, suggesting that, for these regions at least, the dominant process in establishing the observed v-l-rho correlation is a turbulent energy cascade.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 272; Sept. 15
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  • 59
    Publication Date: 2011-08-18
    Description: The CO 1 yields 0 transition at 115 GHz has been mapped over an area of more than 6 deg sq toward W50, the extended SNR surrounding the peculiar object SS 433. W50 is found to lie at the end of a filamentary molecular cloud 4 deg long and 1 deg wide that closely matches a conspicuous dust lane on the Palomar Sky Survey; the cloud's kinematic distance is within 0.7 of 2.2 kpc, in agreement with the distance 2-3.3 kpc estimated for the SNR, and its mass is about 120,000 solar masses. Though there is little evidence of star formation in the molecular filament, or evidence of an interaction between the filament and W50 (or SS 433), the positional coincidence of the two, their similar distance, and their displacement nearly two molecular scale heights from the plane all suggest a physical relationship or common origin. One possibility is that both the molecular filament and the stellar progenitor of W50 were ejected from a large active molecular complex lying in the plane at l = 40 deg.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 272; Sept. 15
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  • 60
    Publication Date: 2011-08-18
    Description: From a survey of observations on ISEE-3, an example of correlated particle and magnetic field observations of a large-scale magnetic loop structure is presented. Bidirectional proton fluxes were observed for a period of 40 hours in the energy range 35-1600 keV approximately 12 hours after the passage of the interplanetary shock of December 11, 1980, and directly after the passage of a discontinuity. For each of the eight logarithmically spaced energy channels, a three-dimensional anisotropy analysis reveals streaming along both directions of the magnetic field. The magnetic field rotated slowly but steadily through approximately 180 deg during this same 40-hour period; this is consistent with the existence of a large-scale loop with extent greater than 0.5 AU. The observations suggest that the particles are being injected into the loop sunward of the spacecraft; they appear as bidirectional fluxes in the outermost regions of the loop arising from a combination of focusing and near scatter-free transport.
    Keywords: ASTROPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 10; Sept
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  • 61
    Publication Date: 2011-08-18
    Description: The first observations of a vortex street in an atmosphere other than that of the earth are presented, made from a sequence of images of Saturn taken by Voyager 2 in August 1981. The analysis of these images shows that the feature sits at the maximum of the westward jet and suggests that it may be produced by material rising up from below the level of the visible clouds.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 10; Sept
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  • 62
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    Publication Date: 2011-08-18
    Description: Seven chips of primarily matrix material from the Antarctic meteorite ALHA 81005 were analyzed by ferromagnetic resonance (FMR) and magnetic hysteresis techniques. The FMR spectra of two chips have a resonance at g of about 2.1 that resembles the g of about 2.1 resonance that is characteristic of lunar soils. Thus the FMR spectra are consistent with the lunar regolith being a progenitor for the matrix material. For the two chips, the FMR surface exposure (maturity) index was about 5 units, which is equivalent to a value for an immature lunar soil. The total concentration of metallic iron is on the order of 0.11 equivalent wt. pct, which is within the observed range for Apollo 16 rocks and soils.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 10; Sept
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  • 63
    Publication Date: 2011-08-18
    Description: Measurements of the Be-10 and Al-26 contents of ALHA 81005 constrain the length and conditions of its exposure to cosmic rays. Calculations based on one-step irradition models imply that the time spent by this object in space is shorter than that spent by most 'asteroidal' meteorites. On the other hand the results are readily consistent with a lunar origin for ALHA 81005.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 10; Sept
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  • 64
    Publication Date: 2011-08-18
    Description: The isotopic abundances of the noble gases (He, Ne, Ar, Kr, Xe) are reported for Antarctic ALHA 81005. It contains solar wind-implanted gases whose absolute and relative concentrations are quite similar to lunar regolith samples but not to other meteorites. ALHA 81005 also contains a large excess Ar-40 component which is identical to the component in lunar fines implanted from the lunar atmosphere. Large concentrations of cosmogenic Ne-21, Kr-82, and Xe-126 in ALHA 81005 indicate a total cosmic ray exposure age of at least 200 million years. The noble gas data alone are strong evidence for a lunar origin of this meteorite.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 10; Sept
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  • 65
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    Publication Date: 2011-08-18
    Description: It is suggested that existing data on the 1908 Tunguska fall precludes an interpretation of the object as an either active or extinct comet fragment. Because a fireball of the Tunguska mass is not efficiently decelerated by the earth's atmosphere, it would at an entry velocity of about 30 km/sec have had to resist aerodynamic pressures greater than one billon dyn/sq cm before disintegrating. The inherently extremely fragile cometary material could not have survived a load of this magnitude. The data on Type II fireballs with prominent terminal flares are extrapolated, to estimate Tunguska's critical dynamic pressure at the same time of explosion as being of the order of 200 million dyn/sq cm, and its preexplosion velocity as about 10 km/sec, thereby ruling out a comet-like orbit. The Tunguska object is most consistently described as a small Apollo-type asteroid, 90-190 m across.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomical Journal (ISSN 0004-6256); 88; Sept
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  • 66
    Publication Date: 2011-08-18
    Description: During the interval from about May through August 1981, when Voyager 2 was inbound to Saturn, the Planetary Radio Astronomy instrument measured repeated, dramatic decreases in the intensity of the Saturn Kilometric Radiation (SKR). The emission dropouts averaged two orders of magnitude below mean energy levels and varied from about 1 to 10 Saturn rotations in duration. Comparison with pre-Saturn encounter Voyager 1 observations (June to November, 1980) shows that the SKR dropouts were unique to the Voyager 2 observing interval, consistent with the closer proximity of Saturn to Jupiter's distant magnetotail in 1981. Further, the dropouts occurred on the average at times when Voyager 2 is known to have been within or near Jupiter's magnetic tail.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; Sept. 1
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  • 67
    Publication Date: 2011-08-18
    Description: The hypersonic pressure balance model of flaring in cometary plasma tails of Ershkovich et al. (1982) has been modified to include the effects of magnetohydrodynamic (MHD) instabilities occurring along the ionopause in the outer-tail regions. The effect of instability is to mix the solar-wind and comet-tail plasmas, increasing the tail magnetic field strength above that calculated from magnetic flux conservation. The earlier model assumed the ionopause to be a tangential discontinuity surface (flux conserving) at all distances, with the result that the magnetic field approached zero in the outer regions of strongly flaring tails. The present model is more realistic and is in better agreement with measurements of cometary plasma tail widths and flaring angles. This agreement leads to an important conclusion that the magnetic flux is not conserved in distant comet tails.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 272; Sept. 1
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  • 68
    Publication Date: 2011-08-18
    Description: The Rayleigh test has been recently invoked as a method of searching a time series for periodic pulsations. In this paper, this technique is discussed and compared to epoch folding, a technique which has had widespread use in X-ray astronomy. It is found that the Rayleigh test provides a more sensitive approach to the search for periodic pulsations when the pulses are sinusoidal or of broad duty cycle, such as those typical of the pulsing X-ray sources. Epoch folding, on the other hand, is more sensitive to the narrow pulses typical of radio pulsars.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 272; Sept. 1
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  • 69
    Publication Date: 2011-08-18
    Description: A quasi-linear diagnostic model using observed solar-related temperatures and a specified solar mean circulation and surface structure to find the solar-related circulation above the clouds of Venus is presented. Despite the greater dependence of model-derived, solar-related circulation on the mean flow than is the case for terrestrial tides, as well as the uncertainty concerning this mean flow, significant conclusions are drawn for the solar-related circulation and thermal structure of Venus. An anomalously large response is found in the polar regions, due to the model's requirement of a process such as dissipation which will act as a major sink for momentum. Dissipation is specified in the model as Rayleigh friction with an unknown free parameter coefficient. In view of this, dissipation is either very efficient by terrestrial standards and accompanied by small solar-related circulation, or similar to that of earth and possessed of a circulation large enough to have an impact on the mean circulation.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 40; June 198
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  • 70
    Publication Date: 2011-08-18
    Description: Explicitly magnetic field-independent relationships that quantitatively connect the thermodynamic state of the confined beta-less-than-one X-ray plasma to the confining magnetic loop characteristics and the stressing velocity at beta greater than about one are presented. The derived relations fall into two categories: (1) diffuse heating resulting from efficient transport of energy throughout the magnetic loop volume, and (2) isolated heating within the electrodynamic dissipation shell. For each of these cases the Joule dissipation, shear viscous dissipation, and compressional dissipation are considered. Each of these models is characterized by three thermodynamic scalings that are parametrized by the magnetic loop properties and by the stressing velocity. Eliminating the magnetic field intermediary from these relations and normalizing the inverse aspect ratio and the magnetic expansion factor with respect to solar conditions results in a single, unique velocity scaling law for each model.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 271; Aug. 15
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  • 71
    Publication Date: 2011-08-18
    Description: Spectra of several carbon stars in the two micron region are examined and compared with synthetic spectra from model atmospheres. Molecular hydrogen has been directly observed in carbon stars for the first time through the quadrupole 1-0 S(1) line at 4712.9/cm. It is definitely present in several Mira variables, and is definitely not present in several irregular variables and one Mira variable. A discrepancy between the predicted and observed line depths at different temperatures is shown. Resolution of the discrepancy by change of temperature alone would require an upward revision of the present effective temperature scale by at least 600 K. Several possible resolutions of the dilemma are briefly examined.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 270; July 15
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  • 72
    Publication Date: 2011-08-18
    Description: Radial intensity scans of a Voyager 2 high phase angle image of Titan have been inverted to yield vertical extinction profiles at 1 deg intervals around the limb. A detached haze layer with peak particle number densities of about 0.2 cu/cm exists at all latitudes south of about 45 N, and at an altitude of 300-350 km. The optical depth 0.01 level lies at a radius of 2932 + or - 5 km at the equator and at a radius of 2915 + or - 10 km over the poles (altitudes of 357 + or - 5 and 340 + or - 10 km, respectively). In addition to the haze layer at 300-350 km, there is a small enhancement in the extinction at about 450 km which exists at all latitudes between 75 deg S and about 60 deg N.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 55; July 198
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  • 73
    Publication Date: 2011-08-18
    Description: The first detection of interference fringes by VLBI at a wavelength of 3.4 mm during observations of 3C84 are reported. The compact source in the nucleus of 3C84 was observed for a 9-hr period on the 485 km baseline between the Owens Valley Radio Observatory and the Hat Creek Observatory. The fringe data are given and the derivation of the correlated flux densities is described. The findings are discused in the context of previous obervations. The results demonstrate that there are no unforeseen technical difficulties associated with millimeter VLBI, and that the sensitivity of existing systems is sufficient to observe objects brighter than a few Jy. The observations are consistent with the millimeter wavelength radio structure of 3C84 being more compact than its centimeter wavelength structure.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 303; June 9
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  • 74
    Publication Date: 2011-08-18
    Description: Voyager imaging, infrared, and radio observations for Saturn have been recently interpreted by Smith et al. (1982) as an indication that the jet streams observed at the cloud tops extend to depths greater than the 10,000-bar level. This analysis assumes a maximum latitudinal temperature contrast of a few percent, a mean atmospheric rotation rate at depth given by Saturn's ratio period, and no variation with latitude of the bottom pressure level for the zonal flow system. These assumptions are not, however, firmly constrained by observation. The diagnostic analysis of plausible alternative configurations for Saturn's atmospheric structure demonstrates that a thin weather layer system (confined at mid to high latitudes to levels above 200 bar) cannot be excluded by any of the available observations. A quantitative estimate of the effects of moisture condensation (including the differentiation of mean molecular weight) suggests that these might provide the buoyancy contrasts necessary to support a thin-layer flow provided that Saturn's outer envelope is enriched approximately 10 times in water abundance relative to a solar composition atmosphere and strongly differentiated with latitude at the condensation level.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: (ISSN 0019-1035)
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  • 75
    Publication Date: 2011-08-18
    Description: The equatorial atmosphere of Titan was probed by means of two coherently related radio signals transmitted from Voyager 1 at 13.0 and 3.6 cm wavelengths during the November 12, 1980 occultation of the spacecraft by the Saturn satellite. An analysis of the differential dispersive frequency measurements did not reveal any ionization layers in the upper atmosphere of Titan. The gas refractivity data, which extend from the surface to about 200 km altitude, were interpreted in two different ways. In the first, it is assumed that N2 makes up virtually all of the atmosphere, with small amounts of CH4 and other hydrocarbons present. In the second interpretation of the refractivity data, it is assumed that the 3.5 km altitude level corresponds to the bottom of a CH4 cloud layer and that N2 and CH4 were perfectly mixed below this level.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 76
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    Publication Date: 2011-08-18
    Description: A discussion is presented on the gravitational interaction between ring systems and nearby satellites. A shepherd satellite lacking damping mechanisms will force oscillations in the motion of a ring particle that are symmetrical with respect to the encounter geometry. If such damping mechanisms as density wave propagation or a dissipative medium are present, a lag in particle response provides the asymmetry that exerts a net torque on the rings. While the torque on a given particle depends on the degree of damping, that dependence disappears when the torque is averaged over a range of orbits spanning resonances if the degree of damping is within a certain range. A torque that is much lower than the standard formula results from excessively weak or strong damping.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 77
    Publication Date: 2011-08-18
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 267
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  • 78
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    Publication Date: 2011-08-18
    Description: It is pointed out that the magnetosphere of Jupiter is in many respects quite different from that of the earth. The energy required to drive the Jovian magnetosphere is apparently extracted from Jupiter's rotational energy rather than from the solar wind. Jupiter is a strong source of energetic charged particles which can be detected as far away as the orbit of Mercury. The structure and dynamics of the energetic particle distribution in the inner magnetosphere is discussed, taking into account observations, transport and losses in the inner magnetosphere, satellite interactions, and electron synchrotron radiation. The subsolar hemisphere is considered, giving attention to particle fluxes in the subsolar magnetosphere, conditions in the middle magnetosphere, and the characteristics of the outer magnetosphere. A description of the predawn magnetosphere is also provided.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 79
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    Publication Date: 2011-08-18
    Description: The original interest in an ionosphere on Jupiter was generated by the discovery of strong radio-frequency emissions at approximately 20 MHz which were thought to be plasma frequencies associated with Jupiter's ionosphere. The ionosphere of Jupiter provides a means to couple the magnetosphere to the atmosphere by virtue of its high conductivity and collisional interaction with the neutral atmosphere. The Pioneer and Voyager have provided direct measurements of profiles of electron concentration at selected locations on Jupiter. Attention is given to basic principles regarding the characteristics of the Jovian ionosphere, the ionization sources, aspects of ion recombination, ion chemistry, observations of Jupiter's ionosphere, the structure of Jupiter's upper atmosphere, and questions of ionospheric modeling. On the basis of the Pioneer and Voyager observations it appears that Jupiter's ionosphere and thermosphere undergo significant solar cycle changes.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 80
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    Publication Date: 2011-08-18
    Description: Silicon dicarbide was first observed in 1926 in spectra of cool carbon stars. The carrier of these bands around 5000 A was tentatively identified as SiC2 by Kleman (1956) who produced similar spectra by inserting silicon into the graphite tube of a King furnace heated to over 2500 K. This identification was strengthened by subsequent mass spectral studies which showed SiC2 as a major molecular component of vaporized silicon carbide. The present investigation is concerned with calculations which were initiated in an attempt to understand more recent astronomical observations of unidentified lines in the millimeter-wave region of the spectrum. The calculations were designed to determine the ground state equilibrium structure and to obtain vibrational and rotational constants. Calculations for estimating the positions and structure of low-lying electronic states were also performed. Self-consistent field (SCF) calculations were performed assuming a closed-shell electronic structure analogous to that in C3. Calculations were conducted for symmetric CSiC, and asymmetric SiCC forms.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 266
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  • 81
    Publication Date: 2011-08-18
    Description: HEAO 1 A-2 and Einstein Solid State Spectrometer (SSS) observations of SMC X-1 are presented. An unpulsed soft component is found with a blackbody temperature of 0.16 keV and an area for the emission region of 10 to the 15th to 10 to the 17th sq cm. The hard X-ray component is pulsed; the phase-averaged spectrum is a power law with alpha of about 0.5 up to 17 keV, above which it steepens. The SSS sets an upper limit of less than 4 x 10 to the 21st H/sq cm to any absorption, and is consistent with that expected from the wind of Sk 160. Absorption dips with a timescale of several hundred seconds are seen immediately following an eclipse exit, and are probably caused by inhomogeneities in the wind of Sk 160.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 266
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  • 82
    Publication Date: 2011-08-18
    Description: The detection of high-velocity H I in absorption against the nuclear continuum source in the giant elliptical galaxy NGC 315 is reported. The absorption line is found to be highly blueshifted in the reference frame of the galaxy with a projected velocity toward the galaxy of 490 km/s. The absorption line is very strong (244 + or - 4 mJy), consisting of two components with very narrow velocity widths of 2.5 km/s (FWHM) each and peak optical depths of 0.9 and 0.2. The kinetic temperature must be 150 K if the line widths are due entirely to thermal broadening, while the neutral gas column densities implied are 2-5 x 10 to the 20th hydrogen atoms/sq cm. No OH in absorption was detected in these clouds to a limiting peak optical depth of 0.04, although this result is consistent with either a galactic or extragalactic origin of the clouds. It is suggested that these clouds may have condensed out of a large unobserved galactic halo of gas, or they may reside in or have been captured from the intracluster medium.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 266
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  • 83
    Publication Date: 2011-08-18
    Description: The effective temperature of a normal star with an absorption-line spectrum is a parameter which represents the total amount of radiative energy emerging from each square centimeter of surface of the star. Effective temperatures have been obtained for 10 Wolf-Rayet stars by means of ultraviolet energies determined from high-resolution International Ultraviolet Explorer (IUE) spectra and energies determined from observations made in the visible range. It is essential to use high-resolution IUE spectra in order to resolve the continuum from many emission lines which are present, particularly shortward of 1900 A. The results confirm what was found earlier, namely that the effective temperatures of Wolf-Rayet stars are similar to those of early B stars. The effective temperature of the central star of the planetary nebula BD 30 deg 3639, HD 184738, is found to be 18,000 K.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 266
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  • 84
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    Publication Date: 2011-08-18
    Description: A cosmological scenario where axions provide the dark matter in the universe is considered. Fluctuations in the axion-field energy denisty produced by domain walls and strings cause the appearance of 'axion clumps' of masses of order 10 to the 6th solar masses which most likely collapse to black holes by or at the time that the universe becomes axion dominated at T approximately 10 eV. These objects form the building blocks for the clustering hierarchy theory of galaxy and supercluster formation on scales up to about 10 Mpc and 10 to the 15th solar masses.
    Keywords: ASTROPHYSICS
    Type: Physical Review Letters; 50; Mar. 21
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  • 85
    Publication Date: 2011-08-18
    Description: Periodic pulsations have been sought in the NGC 1851, 6441, 6624, and 6712 globular cluster sources' X-ray emission, using the Einstein Observatory's Monitor Proportional Counter. Special attention is given to features of the present methods of analysis, which correctly account for several effects that have been routinely overlooked by other researchers. No pulsed emission was detected in the periods searched, which covered from 1 msec to about 500 sec. The 90% confidence upper limits for the pulsed fraction are given.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 266
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  • 86
    Publication Date: 2011-08-18
    Description: Four distinct types of particles are suggested to be present in the upper atmosphere of Venus. The lowest and densest haze may consist of a submicron sulfuric acid aerosol which extends above the cloud tops, up to about 80 km, representing an extension of the upper cloud deck. Temperature structure measurements in the 70-120 km altitude range indicate the occasional appearance of two independent water ice layers, of which the lower may form between 80 and 100 km and is probably the detached haze layer noted in high contrast limb photography. A nucleation of this ice layer on sulfuric acid aerosols is hypothesized. Temperatures of the Venus mesopause, near 120 km altitude, are frequently cold enough to allow ice nucleation on meteoric dust or ambient ions, yielding a haze (analogous to noctilucent clouds on earth) which is expected to be tenuous to the point of optical invisibility.
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  • 87
    Publication Date: 2011-08-18
    Description: The unexplained long-term variability of the light of the brightest nonexplosive stars known, namely the Hubble-Sandage (or S Doradus) variables, is investigated in terms of the following mechanisms: (1) episodic, nearly catastrophic mass loss, perhaps accompanied by temporary shrinkage of the stellar radius, in a luminous supergiant; (2) flickering of a hydrogen-burning or helium-burning shell; (3) hydrogen flashing in an evolved stellar core; (4) pulsation of a luminous supergiant envelope near the Eddington limit of radiative stability; (5) pulsation of a dense circumstellar gas or dust cloud; (6) overturning of giant convection cells (or some other kind or nonradial oscillation) in a luminous supergiant envelope; or (7) vibrational instability and mass outflow in an extremely massive main-sequence star. It is believed that the second and third suggestions can all but definitely be ruled out and that the sixth and seventh are rather unlikely. Preference is given to the notion that a sudden, massive outflow of matter may sometimes occur from the surface of an evolved supergiant of very high mass.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 264
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  • 88
    Publication Date: 2011-08-18
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 264
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  • 89
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    Publication Date: 2011-08-18
    Description: The phosphine photochemistry on Saturn is studied with a 1D photochemical model. The PH3 concentration is rapidly depleted with height (scale height 3.5 km) in the upper troposphere. Formation of P, a probable precursor of P4, (a potential red chromophore in the atmosphere), is highly improbable unless the rate constant for the recombination reaction PH + H2 + M yields PH3 + M is less than 10 to the -41st cm exp 6/molecule-squared sec. Coupling of PH3 and hydrocarbon photochemistry, specifically the C2H2 catalyzed photodissociation of CH, is important. Column production rates of the organophosphorus compounds CH3PH2 and HCP of 3 x 10 to the 8th/sq cm sec are predicted, with potentially observable column densities of greater than 1 x 10 to the 17th/sq cm.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 10; Oct. 198
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  • 90
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    Publication Date: 2011-08-18
    Description: It is now widely believed that Al-26 (half-life, 7.2 x 10 to the 5th yr) and Pd-107 (half-life, 6.5 x 10 to the 6th yr) were present in the early solar system. The nucleosynthetic event responsible for the production of these nuclei must therefore have occurred no more than a few million years before the formation of solid bodies. It is possible that this event also gave a rise to the I-129 believed to be present in the early solar system. The last event to contribute Pu-244 to the solar system, however, occurred approximately 10 to the 8th yr before the time of solidification. It is noted that this latter time scale is also consistent with the lack of evidence for a Cm-247 chronometer. It is proposed that Hf-182 (half-life, 9 x 10 to the 6th yr) can resolve the question whether heavy-element nonactinide nucleosynthesis occurred during the (Al-26)-producing event. It is believed that an answer to this question will help to clarify the chronology of the formation of the solar system and will help to determine the astrophysical sites of heavy-element nucleosynthesis.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 304; Aug. 11
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  • 91
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    Publication Date: 2011-08-18
    Description: The sharp, 90-km wide transition from an optical depth of 0.2 in the C ring to 1 in the B ring begins at 91,970 km from Saturn's center. This radius is found to be almost exactly at the inward stability limit of charged particles launched in the ring plane at the local Kepler velocity, provided these particles have large charge to mass ratio. The zonal harmonic models of Saturn's magnetic field from the Voyager data and the gravitational field model from Pioneer data are essential to get the very close agreement between theory and observation. The theoretical stability limits are 91,973 + or - 145 km from Voyager 1 magnetic field data and 91,991 + or 145 km from Voyager 2 magnetic data. The zonal harmonic magnetic field lines are not perpendicular to the ring plane. Therefore, in addition to the magnetic mirror, gravitational, and centrifugal forces, an unknown force must be postulated to produce equilibrium in the ring plane and make the stability calculation meaningful.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; Aug. 1
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  • 92
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    Publication Date: 2011-08-18
    Description: The current theoretical understanding of the properties of X-ray pulsars is assessed through a comparison with unified descriptions of 14 such systems, extending over six orders of magnitude in luminosity, in whose phase averaged spectra the only notable trend is a less abrupt high energy cutoff in the lower luminosity systems. Detailed pulse phase spectroscopy is given for five of the systems. A reexamination of the pulse phase spectra of 4U 0115 + 63 has uncovered electron cyclotron lines at 11.5 and 23 keV that appear to be in absorption at pulse peak and in emission during an interpulse. Spectral hardening regions such as those from Her X-1 are a common feature in the low energy pulse of many pulsars, and may represent the passage of the magnetic axis through the observer's line of sight. Attention is given to the nature of the beaming from Her X-1, and it is concluded that a pencil beam configuration represents the simplest explanation of the overall properties of the pulse.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 270; July 15
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  • 93
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    Publication Date: 2011-08-18
    Description: The scalloped outermost edge of the Galaxy may be driven by a Kelvin-Helmholtz interface instability if the disk and halo components of the Galaxy at large galactocentric distances do not corotate. The range of unstable wavelengths is found to be 10-23 kpc, in good agreement with the observed wavelength, 19 kpc.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 270; July 15
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  • 94
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    Publication Date: 2011-08-18
    Description: Significant abundances of trapped argon, krypton, and xenon have been measured in shock-altered phases of the achondritic meteorite Elephant Moraine 79001 from Antarctica. The relative elemental abundances, the high ratios of argon-40 to argon-36 (equal to or greater than 2000), and the high ratios of xenon-129 to xenon-132 (equal to or greater than 2.0) of the trapped gas more closely resemble Viking data for the Martian atmosphere than data for noble gas components typically found in meteorites. These findings support earlier suggestions, made on the basis of geochemical evidence, that shergottites and related rare meteorites may have originated from the planet Mars.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 221; Aug. 12
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  • 95
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    Publication Date: 2011-08-18
    Description: The collapse of a very low thermal energy, rotating cloud results in fragmentation to a binary protostellar system even in the nonisothermal regime. The solar system therefore probably did not form from a fragmentation hierarchy involving ejection of the presolar nebula from a multiple system.
    Keywords: ASTROPHYSICS
    Type: Icarus (ISSN 0019-1035); 55; July 198
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  • 96
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    Publication Date: 2011-08-18
    Description: The role of adsorbed SO2 on Io's surface particles in producing the observed spectral absorption band near 4 microns in Io's reflectance spectrum is explored. Calculations show that a modest 50 percent monolayer coating of adsorbed So2 molecules on submicron grains of sulfur or alkali sulfide, assumed to make up Io's uppermost optical surface ('radialith'), will result in a nu 1 + nu 3 absorption band near 4 microns with depth about 30 percent below the adjacent continuum, consistent with the observed strength of the Io band. The precise wavelength position of the nu 1 + nu 3 band of SO2 in different phase states such as frost, ice, adsorbate, and gas are summarized from the experimental literature and compared with the available telescopic measurements of the Io band position. The results suggest that the 4-micron band in Io's full disk spectrum can best be explained by the presence on Io's surface of widespread SO2 in the form of adsorbate rather than ice or frost.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 54; June 198
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  • 97
    Publication Date: 2011-08-18
    Description: HCN formation in the upper troposphere and lower stratosphere of Jupiter is presently modeled in terms of UV pyrolysis of the C2H5N isomer aziridine, which is a product of the NH2 and C2H3 radicals that originate from ammonia photolysis and the addition of H atoms to acetylene, respectively. The sensitivity of the HCN column density to the individual rate constants and the eddy diffusion coefficient profile is considered, along with the possibility that additional HCN-yielding pathways may exist. Both ammonia and phosphine are strongly depleted by photolysis.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 54; June 198
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  • 98
    Publication Date: 2011-08-18
    Description: Ultraviolet spectra of the peculiar eclipsing binary Epsilon Aurigae (FO Ia + ?) were obtained with the International Ultraviolet Explorer at pre-eclipse and ingress partial phases. The results show a wavelength dependence of the eclipse in contrast to the grayness (non-wavelength dependence) of the eclipse observed in visible light. From the current results, incorporating previous observations, it is suggested that: (1) the obscuration of the light of the F supergiant by the disk proposed by Huang (1965) is the result of electron scattering in visible light; (2) the increase in the eclipse depths toward shorter wavelengths observed in the ultraviolet is caused by dust; and (3) the temperature of the disk is in the range from 1000 to 2000 K.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 269; June 1
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  • 99
    Publication Date: 2011-08-18
    Description: An exact numerical calculation is provided for of linear growth and phase velocity of Kelvin-Helmholtz unstable wave modes on a supersonic jet of cylindrical cross section. An expression for the maximally unstable wavenumber of each wave mode is found. Provided a sharp velocity discontinuity exists all wave modes are unstable. A combination of rapid jet expansion and velocity shear across a jet can effectively stabilize all wave modes. The more likely case of slow jet expansion and of velocity shear at the jet surface allows wave modes with maximally unstable wavelength longer than or on the order of the jet radius to grow. The relative energy in different wave modes and effect on the jet is investigated. Energy input into a jet resulting from surface instability is discussed. Previously announced in STAR as N83-17379
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 269; June 1
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  • 100
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    Unknown
    In:  Other Sources
    Publication Date: 2011-08-18
    Description: It is speculated that the periodic absorption and desorption of CO2 by the soil of Venus may buffer daily temperature, pressure and wind variations in the lower atmosphere, effectively eliminating the net tidal torque on the atmosphere. The redistribution of mass would still generate a sizable torque, however, which may serve as a balance for that which is caused by the gravitationally induced tide. This novel tidal mechanism represents a somewhat weaker competitor to the atmospheric tides which have previously been studied.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 54; June 198
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