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  • GEOPHYSICS  (1,368)
  • Chemical Engineering  (1,001)
  • ASTROPHYSICS  (826)
  • 1985-1989  (2,340)
  • 1965-1969  (855)
  • 1950-1954
  • 1988  (2,340)
  • 1966  (855)
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  • 1985-1989  (2,340)
  • 1965-1969  (855)
  • 1950-1954
Year
  • 1
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    Carbon and nitrogen lines in the spectra of Wolf-Rayet stars (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The one-representative-point radiative transfer theory of Castor and van Blerkom (1970) is used to predict the relative energies in emission lines of the ions of carbon and nitrogen in Wolf-Rayet atmospheres for a wide range of parameters. The predicted ratios are compared with observed relative energies of lines in the visible and ultraviolet spectral ranges of six Wolf-Rayet stars. It is found that the lower levels of C II, C III, N III, and N IV are strongly overpopulated relative to their populations in LTE. The differences between WC and WN spectra appear to be due chiefly to a difference in electron temperature in the line-emitting regions. The typical volume of stars studied is estimated to be in the range of 10 to the 41st to 10 to the 44th cu cm. Possible ways in which the line-emitting regions may be arranged around the star are discussed, noting that the high-temperature line-emitting plasma may lie in a thin annular disk approximately 10 to the 15th cm from the star.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 67; 187-223
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  • 2
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    Bow shocks and bubbles are seen around hot stars by IRAS (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Examination of the IRAS all-sky imagery reveals extended, arcuate, and ringlike features associated with hot luminous stars. They fall into a number of classes: stellar wind bow shocks, stellar wind bubbles, dust shells, dust heated by isolated B stars, bright rims, and dust in H II regions. Here, some objects are discussed in which the star exercises structural control over the spatial distribution of dust: bow shocks, bubbles, and radiation pressure-driven shells. A list of the 15 most prominent objects is presented, a few prototypes are shown, and their characteristics are explained in terms of thermal emission processes and gasdynamics.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 329; L93-L96
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  • 3
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    Bimodal abundances in the energetic particles of solar and interplanetary origin (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This letter reports the first results from an examination of the daily-averaged abundances of the elements from H through Fe as well as electrons and isotopes of He in energetic particles observed in interplanetary space by the ISEE 3 spacecraft over an 8.5 yr period. The abundances of heavy elements such as Fe/O show, for the first time, clear evidence of the presence of two distinct populations of particles. Earlier observations could be interpreted as extreme variations within a single population. The population with enhanced Fe/O shows correlated enhancements in He-3/He-4, p/e, and He/H. This population is consistent with material that has been processed to high temperatures in the impulsively heated regions of solar flares. The second population, with more normal abundances, is probably accelerated from ambient material by coronal and interplanetary shocks.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 330; L71-L75
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  • 4
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    Theoretical infrared spectra of SN 1987A (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A simple model for the ejecta of SN 1987A is used to show that the expected fluxes in infared fine structure lines from nickel, cobalt, iron, argon, sulfur, silicon, and neon are likely to be detectable for several years following the supernova explosion. Energy sources due to radioactive decay and a central pulsar are considered separately. Most of the mass of heavy elements resides in the inner, pure metal shells of the ejecta, so that the infrared lines will probe the temperature, ejecta masses, and dynamics of this region and not the overlying, hydrogen-rich envelope.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 329; L25-L28
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  • 5
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    Laboratory studies of the infrared spectral propertries of CO in astrophysical ices (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The spectral properties of CO in various ices are presented. Included are peak positions, FWHMs, band profiles, and integrated absorbances of the CO fundamental at 2137/cm in different ices under various conditions. The results reveal that good quality moderate-resolution spectra of the interstellar CO feature can be used to unravel the composition, temperature, and thermal history of interstellar and cometary ices containing CO.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 329; 498-510
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  • 6
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    A comparison of solar irradiances measured by SBUV, SME, and rockets (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In this paper, Solar Backscatter Ultraviolet (SBUV) measurements of solar irradiance and predictions from the Mg 280-nm index are compared with each other and with coincident Solar Mesosphere Explorer (SME) and rocket measurements. The SBUV irradiances show a systematic decrease with time not seen in the rocket measurements; a correction for this decrease is introduced. The scatter and overall structure in the SME spectra is 3-5 percent, of the order of or larger than most of the changes predicted by the Mg index. The corrected SBUV ratio and the Mg index prediction for it agree to within 1 percent. Such agreement supports a common origin for variations between solar maximum and minimum and those for individual rotations: the degree to which active regions cover the visible hemisphere of the sun.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 7091-710
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  • 7
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    Effect of solar proton events in 1978 and 1979 on the odd nitrogen abundance in the middle atmosphere (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Daily average solar proton flux data for 1978 and 1979 are used in a proton energy degradation scheme to derive ion pair production rates and atomic nitrogen production rates. The latter are computed in a form suitable for inclusion in an atmopheric, two-dimensional, time-dependent photochemical model. Odd nitrogen distributions are computed from the model, including atomic nitrogen production from solar protons, and are compared with baseline distributions. The comparisons show that the average effect of the solar protons in 1978 and 1979 was to cause changes in odd nitrogen only above 10 mbar and at latitudes only above about 50 deg in both hemispheres. The influence of the solar proton-produced odd nitrogen on the local abundance of odd nitrogen depends primarily on the background odd nitrogen abundance as well as the altitude and season.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 7084-709
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  • 8
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    A catalog of interplanetary type III storms (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A catalog describing the characteristics of all the interplanetary type III storms observed at kilometric wavelengths by the radio astronomy experiment on the ISEE-3 spacecraft between September 1978 and October 1982 is presented. Three-dimensional trajectories have been determined for about one-third of these storms using radio techniques. Solar coordinate and solar wind parameters derived from the trajectories are also tabulated. A statistical summary of the data is included.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics Supplement Series (ISSN 0365-0138); 73; 2, Ma
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  • 9
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    Non-seasonal changes in total column ozone from satellite observations, 1970-86 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Analyses of nonseasonal changes in total column ozone from satellite observations during the period 1970-86 suggest, when combined with analyses of Dobson network data, that the largest reduction in global ozone since 1959 occurred between 1978 and 1986. The existence of an Arctic region of enhanced ozone depletion with similar but less pronounced characteristics of the Antarctic region is described. Before 1983 large rates of decrease were confined to high latitudes, subsequently regions of large rates of ozone depletion have appeared at midlatitudes.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 219-227
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  • 10
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    Mass extinctions, atmospheric sulphur and climatic warming at the K/T boundary (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The possible climatic effects of a drastic decrease in cloud condensation nuclei (CCN) associated with a severe reduction in the global marine phytoplankton abundance are investigated. Calculations suggest that a reduction in CCN of more than 80 percent and the resulting decrease in marine cloud albedo could have produced a rapid global warming of 6 C or more. Oxygen isotope analyses of marine sediments from many parts of the world have been interpreted as indicating a marked warming coincident with the demise of calcareous nannoplankton at the K/T boundary. Decreased marine cloud albedo and resulting high sea surface temperatures could have been a factor in the maintenance of low productivity in the 'Strangelove Ocean' period following the K/T extinctions.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 63-65
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  • 11
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    Extremely low N2O concentrations in the springtime stratosphere at McMurdo Station, Antarctica (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Measurements have been made of stratospheric N2O using the Stony Brook millimeter-wave remote sensing spectrometer at McMurdo Station, and NO2 mixing ratios are found that are less than 1.5 at 20 km and less than 1.10 at 25 km compared to values measured during the Antarctic summer. The observed mixing ratios are also much less than those predicted by global-scale models of stratospheric chemistry and dynamics. As the NO2 signal remained very weak when McMurdo was at the edges of the ozone hole and showed no signs of recovering during October, it is concluded that the geographical and temporal extent of the region of low NO2 is comparable to or greater than that of the ozone hole. These results argue against theories that require springtime upwelling to explain the Antarctic ozone hole. It is suggested that the air in the Antarctic lower stratosphere during late winter and early spring has been subjected to considerable downward transport.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 53-55
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  • 12
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    Effect of computed horizontal diffusion coefficients on two-dimensional N2O model distributions (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The effects of horizontal diffusion coefficients K(yy) and K(yz), computed directly from the residual circulation, on the N2O distribution in a photochemical model were investigated, using a modified version of the two-dimensional model of Guthrie et al. (1984). The residual circulation was computed using the NMC's temperature data and the heating rates reported by Rosenfield et al. (1987). As compared with the effect of the residual circulation alone, the use of horizontal diffusion coefficients produced substantial changes in the N2O distribution and increased the N2O's lifetime values by a few percent. It is suggested that trace gases, such as CH4, CFCl3, CF2Cl2, CH3Cl, and CCl4, which impact the NO(x), HO(x), and Cl(x) radical distributions and therefore ozone, will be influenced in a similar manner by the addition of more realistic diffusion fields.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 5213-521
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  • 13
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    VLF noises triggered by whistlers as observed in the topside ionosphere (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: ISIS-1, ISIS-2, and DE-1 VLF electric field data from Kashima station, Japan are used to investigate characteristics of whistler triggered emissions in the topside ionosphere. The occurrence rate for nonducted whistler triggered emission is shown to be distributed randomly between L = 2.0 and 4.2, while the occurrence rate of ducted whistler triggered emissions increases with latitudes between L = 1.5 and 2.9, attains a maximum at L = 2.7, and abruptly drops off at L = 3.0. The findings indicate that some whistler triggered emissions may be generated by the interaction of whistlers with magnetospheric electrons.
    Keywords: GEOPHYSICS
    Type: Radio Research Laboratory, Journal (ISSN 0033-8001); 35; 15-26
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  • 14
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    Effect of a uniform sea-level change on the earth's rotation and gravitational field (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Global water redistriburtion between the oceans, atmosphere and continents causes changes in the earth's rotation and gravitational field. To conserve water mass, the effect of the small uniform change in sea-level must be considered. Explicit formulas are provided for these sea-level corrections to the gravitational Stokes coefficients, polar motion and length of day. In two recent publications, this sea-level correction term for polar motion was given incorrectly. These errors which arose from normalization conventions with the ocean function are corrected.
    Keywords: GEOPHYSICS
    Type: Geophysical Journal (ISSN 0952-4592); 93; 191-193
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  • 15
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    Comparison of SAGE II solar extinction data with airborne measurements of atmospheric backscattering in the troposphere and lower stratosphere (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In April 1986, during passage of the SAGE I satellite, the first simultaneous measurements of the atmospheric backscattering coefficient beta (pi, 10.6 microns) were made with an airborne CO2 lidar. Individual ratios of beta and the SAGE II extinction sigma (1.02 micron) are in reasonable accord with previously calculated values. The trend with height shows a distinctly nonlinear relation, which is probably attributable to steadily changing size distributions of aerosols.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 709-711
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  • 16
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    Radio properties of the highly polarized, quiescent quasar OI 287 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The highly polarized, quiescent quasar OI 287 has been observed with high resolution at 2 cm and 6 cm in an effort to determine the origin of some of the object's peculiar properties. The results seem to rule out the classification of OI 287 as a blazar. Extrapolation of the radio core spectrum to midinfrared wavelengths fails to predict the infrared flux by at least an order of magnitude. This supports the conclusion that the infrared emission and the radio emission do not originate in the same synchrotron-emitting component. The high optical polarization could be related to possible broad absorption lines in the unobserved UV regime, or it could be caused by reflection into the line of sight by scattering agents distributed in a thin disk.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 328; 569-577
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  • 17
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    X-ray and gamma-ray emissions expected from supernova 1987A (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The X-ray and gamma-ray spectra expected from SN 1987A have been calculated. Results for the TWOBF7 model are inconsistent with Ginga observation, but the X-ray flux and its spectral shape strongly depend on the chemical composition and expansion velocity of the ejecta. The distributions of density and chemical compositions for SN 1987A are described. For the TWOBF7 model, the X-ray flux between 10 and 20 keV reaches a peak of 6.7 photons/s/sq m about 1 yr after the explosion. For the 15B5 model, the peak flux is larger by a factor of five. The implications of the Ginga satellite's detection of an excess X-ray flux from the direction of the supernova for the models of SN 1987A are considered. How observations of gamma-ray lines can determine the optical thickness of the expanding shell is discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 328; 699-703
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  • 18
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    Balloon-borne measurements of middle atmosphere aerosols and trace gases in Antarctica (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper reviews data on in situ balloon-borne measurements on stratospheric ozone concentrations and aerosol contents obtained prior to 1986, along with the measurements obtained in 1986 during the National Ozone Expedition. The data indicate that the phenomenon of ozone depletion appears to be shaped spatially and temporally by dynamical stratospheric phenomena. In terms of Antarctic stratospheric research, it appears that the most important problems at the moment involve delineating the springtime ozone depletion through accurate in situ measurements of temperature, trace gas, and particle size (in addition to remote sensing from space).
    Keywords: GEOPHYSICS
    Type: Reviews of Geophysics (ISSN 8755-1209); 26; 113-130
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  • 19
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    R Aquarii - The large-scale optical nebula and the Mira variable position (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The R Aquarii symbiotic star system is surrounded by a large-scale optical nebula. Observations of the nebular forbidden O III structure are presented and its morphological significance are discussed in context with previously observed small-scale radio-continuum features, which may be related. It is suggested that a precessing accretion disk may explain the global features of both the large-scale optical emission and the small-scale radio emission. Moreover, an accurate position has been determined of the system's Mira, which suggests that a recent theoretical model, yielding an egg-shaped central H II region for symbiotic systems with certain physical parameters, may apply to R Aquarii. The optical position of the 387 d period Mira variable is consistent with previous findings in the radio, that SiO maser emission is far removed from the Mira photosphere.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 95; 1478-148
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  • 20
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    Axions from 1987A (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The process of axion emission from SN 1987A by nucleon-nucleon axion bremsstrahlung is investigated based on neutrino observations. The results indicate that the axion luminosity must be less than about 10 to the 53rd erg/s if: (1) axions couple very weakly (with an axion mass of less than about 0.75 x 10 to the -3rd); or (2) axions couple strongly enough to be trapped and radiated from an axion sphere with T sub a of less than about 8 MeV (with an axion mass of greater than about 2.2 eV). Axion trapping is found to occur for axion masses of greater than about 0.016 eV.
    Keywords: ASTROPHYSICS
    Type: Physical Review Letters (ISSN 0031-9007); 60; 1797-180
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  • 21
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    Turbulent diffusivity (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A method for determining the turbulent diffusivity tensor is proposed which has application to problems such as the mixing in the interior of the sun for the solar neutrino problem, the chemical evolution of the galaxy, and grain sedimentation on the primitive solar nebula. A model for determining the turbulent energy spectral function, the eddy decorrelation rate, and the growth rate of the underlying instability is discussed. Good agreement is obtained between the present values for the coefficient of turbulent diffusivity and those obtained from both numerical simulation studies and laboratory data on shear turbulence.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 193; 1-2,
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  • 22
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    A ground-based technique for millimeter wave spectroscopic observations of stratospheric trace constituents (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Recent concern over possible long term stratospheric changes caused by the introduction of man-made compounds has increased the need for instrumentation that can accurately measure stratospheric minor constituents. The technique of radio spectroscopy at millimeter wavelengths was first used to observe rotational transitions of stratospheric ozone nearly two decades ago, but has not been highly developed until recently. A ground-based observing technique is reported which employs a millimeter-wave superheterodyne receiver and multichannel filter spectrometer for measurements of stratospheric constituents that have peak volume mixing ratios that are less than 10 to the -9th, more than 3 orders of magnitude less than that for ozone. The technique is used for an extensive program of observations of stratospheric chlorine monoxide and also for observations of other stratospheric trace gases such as (O-16)3, vibrationally excited (O-16)3, (O-18)2(O-16), N2O, HO2, and HCN. In the present paper, analysis of the observing technique is given, including the method of calibration and analysis of sources of error. The technique is found to be a reliable means of observing and monitoring important stratospheric trace constituents.
    Keywords: GEOPHYSICS
    Type: Radio Science (ISSN 0048-6604); 23; 106-118
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  • 23
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    Comment on 'A new method of forecasting geomagnetic activity and proton showers' by A. Hewish and P.J. Duffet-Smith (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: GEOPHYSICS
    Type: Planetary and Space Science (ISSN 0032-0633); 36; 205
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  • 24
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    Self-similar dynamics of polytropic gaseous spheres (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The fundamental equations governing the self-similar dynamics of 'polytropic' gaseous spheres are derived, and the asymptotic solutions are given. The solutions divide into cases with and without 'critical points' in closed analogy with the solar wind solutions of Holzer and Axford (1970). Properties for solutions with critical points are discussed, and their behavior around the critical point is derived explicitly for n = 1. Numerical examples of self-similar solutions for n = 1 and n = 2 - gamma are presented, and the properties of the solutions are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 326; 527-538
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  • 25
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    Magnetic clouds, geomagnetic disturbances, and cosmic ray decreases (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Nineteen magnetic clouds are identified in the years from 1978 through 1982 and studied using superposed epoch analysis. The magnetic-field intensity, proton density and proton temperature are enhanced ahead of magnetic clouds that are preceded by shock, while strong magnetic-field intensity and low proton temperature are observed within the clouds. A relatively large (about 2.5 percent) decrease in cosmic-ray intensity is associated with magnetic clouds that are preceded by a shock, perhaps caused by the turbulent sheath behind an interplanetary shock ahead of the magnetic cloud, whereas only a small (0.5 percent) decrease in intensity is associated with the magnetic cloud itself. Magnetic clouds can produce geomagnetic activity with a decrease in Dst index of the order 100 gamma. The magnitude of the change in the Dst index for the case when southward fields arrive first is comparable to that for the case when northward fields arrive first, and the phase is such that geomagnetic activity is associated with southward fields.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 2511-251
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  • 26
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    The microwave spectrum of asteroid Ceres (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper presents new measurements of the microwave flux of Ceres obtained at wavelengths between 3.3 mm and 20 cm using the 12 m Kitt Peak antenna and the Very Large Array. These new measurements are combined with previous measurements to confirm a substantial decrease in flux density at centimeter wavelengths compared to millimeter wavelength. Using a statistical technique adapted from terrestrial microwave remote sensing, this spectrum has been compared with that of various candidate materials and models for the subsurface structure of Ceres. It is concluded that Ceres is largely covered with a 3-cm-thick layer whose dielectric properties resemble dry terrestrial clay. This layer may have formed by micrometeorite impact on hydrothermally altered basic or ultrabasic rock or on carbonaceous chondrite material.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 95; 1263-126
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  • 27
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    Images of star-forming regions. II - The circumstellar environment of L1551 IRS 5 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The circumstellar environment of L 1551 IRS 5 is investigated based on high-resolution 8000 A (i) and 9000 A (z) broadband CCD images. A small conical reflection nebula extending from a bright semistellar knot located near the cusp of the nebula is noted. It is suggested that the point-like structure at lambda of less than about 3.7 microns may represent a bright knot of dust-scattered light located on the inner surface of a flattened circumstellar disk surrounding the radio source. Evidence is found of sharp changes in the position angle of the jet emanating from IRS 5, possibly resulting from precession of the jet nozzle provided by a dense inner disk which has dynamically decoupled from the much larger flattened molecular structure.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 95; 1173-118
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  • 28
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    The ultraviolet spectra of M31 globular clusters (1988)
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    Publication Date: 2011-08-19
    Description: Ultraviolet spectra of 11 of the brightest globular clusters in M31 show that some exhibit residual flux below 3000 A, greater than that expected from the bright, evolved stars in the cluster. There seems to be no apparent correlation of the strength of this ultraviolet flux with parameters such as metallicity, U-B color, visual magnitude, X-ray emission, or location within the parent galaxy. However, comparison of the ultraviolet colors of the M31 globular clusters with those in the Galaxy and in the Large Magellanic Cloud suggests that the M31 clusters may contain a high percentage of blue horizontal-branch stars or that some clusters could be as young as about 2 x 10 to the 9th yr.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 95; 1071-108
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  • 29
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    Evidence for a radio flare in the nucleus of Virgo A (1988)
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    Publication Date: 2011-08-19
    Description: An increase in radio emission has been observed in the nucleus of the galaxy Virgo A by use of VLBI measurements. These 2.29 GHz observations show that the correlated flux density of the milliarcsec structure increased by 30 percent during a four month period in 1977, and eventually returned to the preflare level of about 0.6 Jy. Previous evidence had indicated that the nuclear radio emission was stable, a surprising result for an active galactic nucleus.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 95; 1037-103
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    Alignments of brightest cluster galaxies with large-scale structures (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Using an independent sample of brightest galaxies in rich clusters in the southern galactic hemisphere, the Argyres et al. (1986) result that galaxy counts on scales to at least 15/h Mpc are systematically higher in the direction of the major axes of brightest cluster galaxies is confirmed.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 95; 996-998
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    Statistics of galaxy orientations - Morphology and large-scale structure (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Using the Uppsala General Catalog of bright galaxies and the northern and southern maps of the Lick counts of galaxies, statistical evidence of a morphology-orientation effect is found. Major axes of elliptical galaxies are preferentially oriented along the large-scale features of the Lick maps. However, the orientations of the major axes of spiral and lenticular galaxies show no clear signs of significant nonrandom behavior at a level of less than about one-fifth of the effect seen for ellipticals. The angular scale of the detected alignment effect for Uppsala ellipticals extends to at least theta of about 2 deg, which at a redshift of z of about 0.02 corresponds to a linear scale of about 2/h Mpc.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 95; 975-984
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    Indirect IUE observation of O VI from photoexcited fluorescence lines of Fe II, present in the spectrum of RR Telescopii (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A new, highly excited level of Fe II at 13.7 eV has been established by means of six lines in the laboratory spectrum below 2000 A. Confirming transitions appear in the infrared region. Four of the ultraviolet lines coincide with previously unidentified lines in the IUE spectrum of RR Tel reported by Penston et al. in 1983. One of the remaining UV lines coincides with the resonance line of O VI at 1032 A, outside the range of the IUE. This suggests that the new FE II level is selectively photoexcited by O VI in RR Tel, resulting in the strong fluorescence lines observed. This case of a Bowen mechanism provides an indirect observation of O VI, important for diagnostics of, e.g., symbiotic stars.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 327; L85-L88
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    On nonsteady accretion in stellar wind-fed X-ray sources (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The paper reports on the results of hydrodynamical simulations of nonaxisymmetric gas flow past a finite-sized gravitating object. The asymmetry in the flow is assumed to be due to a transverse density gradient. The solutions are found to be highly time-dependent and exhibit phases in which a disk forms. The direction of circulation of the disk alternates between the direct and counter sense on time scales of approximately 1 hr. While the disk is present, the specific angular momentum is high, and the mass accretion rate, low. The angular momentum capture oscillates about a mean which secularly increases. Such temporal behavior may be relevant to those X-ray pulsing systems (e.g., Vela X-1) which exhibit fluctuations in the X-ray luminosity and pulse period on time scales much shorter than the orbital period of the binary system.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 327; L73-L76
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    Moment constraints on physical models for quasi-periodic oscillations from Galactic X-ray sources (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Shot-noise models provide a useful mathematical representation for some physical models for the quasi-periodic oscillations (QPOs) recently observed from several bright Galactic bulge and burst X-ray sources. Expressions are calculated for the first three moments for several versions of QPO shot-noise models that have appeared in the literature. It is shown that measurement of the third moment, together with measurement of the mean intensity and the power spectrum, can provide model-dependent constraints on important parameters of QPO shot-noise models, including the fraction of the X-ray intensity in shots and the shot rate. Under certain condtitions, a complete solution for all the shot-model parameters is possible.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 327; 742-749
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    Primordial lithium - New reaction rates, new abundances, new constraints (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Newly measured nuclear reaction rates for H-3(alpha, gamma)Li-7 (higher than previous values) and Li-7(p, alpha)He-4 (lower than previous values) are shown to increase the Li-7 yield from big band nucleosynthesis for lower baryon-to-photon ratio (less than about 4 x 10 to the 10th). Recent revisions in the He-3(alpha, gamma)Be-7 and the D(p, gamma)He-3 rates enhance the high (greater than 4 x 10 to the 10th) Li-7(Be) production. New, independent determinations of Li abundances in extreme population II stars are in excellent agreement with the work of Spites and give continued confidence in the use of Li-7 in big bang baryon density determinations.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 327; 750-754
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    Ultraviolet spectroscopy of the 'jetlike' condensations of NGC 4151 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The spectrometers aboard the IUE are used to obtain UV spectroscopy of the jetlike condensations seen extending 18 arcsec from the nucleus of the nearby Seyfert 1 galaxy NGC 4151. New data reduction techniques are used to detect, delineate, and measure weak nebular emission in IUE spectra. Spatially resolved extended emission is seen in both semiforbidden C III 1909 A and C IV 1549 A. The deduced integrated fluxes in the jet are 10 to the 14th and 4 x 10 to the 14th ergs/sq cm/s for C III and C IV, respectively. The observed fluxes are compared with predictions based upon a central source photoionization model. The implied high C IV/C III flux ratio is shown to be inconsistent with this model and suggests an additional source of ionization for the jet.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 327; 664-670
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    Cosmic strings and the microwave sky. I - Anisotropy from moving strings (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A method is developed for calculating the component of the microwave anisotropy around cosmic string loops due to their rapidly changing gravitational fields. The method is only valid for impact parameters from the string much smaller than the horizon size at the time the photon passes the string. The method makes it possible to calculate the temperature pattern around arbitrary string configurations numerically in terms of one-dimensional integrals. This method is applied to temperature jump across a string, confirming and extending previous work. It is also applied to cusps and kinks on strings, and to determining the temperature pattern far from a strong loop. The temperature pattern around a few loop configurations is explicitly calculated. Comparisons with the work of Brandenberger et al. (1986) indicates that they have overestimated the MBR anisotropy from gravitational radiation emitted from loops.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 327; 584-614
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    Diurnal variation of nitric oxide at 32 km - Measurements and interpretation (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Balloon observations of NO and ozone near sunset and sunrise around 32 km were made on September 19 and October 4, 1985 from Aire sur l'Adour, France. The NO concentration built up rapidly after sunrise, remained fairly steady during the day, and decreased slowly near sunset. This variation is interpreted quantitatively in terms of current photochemistry in relation to ozone.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 2451-546
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  • 39
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    The detection of high-velocity outflows from M8E-IR (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A high-resolution (0.059/cm) M band (4.6 micron) spectrum of the embedded young stellar object M8E-IR is presented and discussed. The spectrum shows strong absorption to large blueshifts in the rotational lines of the fundamental vibrational band, v = 1-0, of CO. The absorption is interpreted as being due to gas near to, and flowing from, the central object. The outflowing gas is warm (95-330 K) and consists of discrete velocity components with the very high velocities of 90, 130, 150, and 160 km/s. On the basis of a simple model, it is estimated that the observed outflows are less than 100 yr old.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 327; L17-L21
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    The effects of mixing of the ejecta on the gamma-ray lines from SN 1987A (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Mixing of matter in the ejecta is suggested by hydrodynamical calculations for SN 1987A. The X-ray flux calculated including mixing reproduces well the observed X-ray light curve and spectra. The effects of mixing on the gamma-ray lines have been estimated. The line fluxes at times less than 1.5 yr after the explosion strongly depend on mixing, and are greatly increased for values of the mixed mass larger than 4 solar masses. The peak advances to an earlier time and its flux is also greatly enhanced. If 5 solar masses are adopted for the mixed mass, as suggested from the X-ray calculations, the 847 keV line will reach its peak around 1.1 yr after the explosion with flux of 0.00086 photons/sq cm per s. If the mixed mass is less than 4 solar masses, the mixing effect becomes less prominent. The gamma-ray lines expected from SN 1987A should be observable. The way in which gamma-ray line observations can be used to diagnose properties of the ejecta is discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 327; L9-L12
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    A bound on X-ray emission from the intrasupercluster medium (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The Bahcall-Soneira (1984) complete sample of superclusters was searched for X-ray emission in the HEAO 1 A-2 data base. No statistically significant emission from diffuse intrasupercluster gas was detected; a 3-sigma upper limit to the mean individual flux is 10 to the -11th ergs/sq cm per s. Implications of this bound to measurements of the Zeldovich-Sunyaev (1969) effect toward clusters within a supercluster and to the supercluster contribution to the cosmic X-ray background are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 327; L1-L3
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    The effects of mixing of the ejecta on the hard X-ray emissions from SN 1987A (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The X-ray and gamma-ray emissions expected from SN 1987A have been calculated, taking into account mixing of material in the ejecta. Nuclear gamma rays emitted by Co-56 are scattered down to the hard X-ray band by multiple Compton scatterings. Nomoto's 11E1Y6 model for the ejecta of SN 1987A is used. X-ray light curves in the 10-30 keV band and spectra above 20 keV calculated with an inner mixed region of 5 + or - 1 solar mass are consistent with the observations performed with the Ginga satellite and the Kvant/Roentgen mission. On the basis of this comparison, further evolutions of the hard X-ray, gamma-ray, and optical/infrared emissions are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 327; L5-L8
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    Light echoes - Novae (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The sudden brilliance of a nova eruption will be reflected on surrounding dust grains to create a phantom nebula. Previous searches for these light echoes have used relatively short exposures with photograhic detectors. This paper reports on a search around eight recent novae with long exposures using a CCD camera. Despite an increase of sensitivity by over an order of magnitude, no light echoes were detected. It is found that the average grain density must be less than about 10 to the -9th per cu cm for distances from 0.1 pc to 1000 pc from the novae. The light echo around Nova Persei 1901 was caused by reflection off clouds with grain densities of several times 10 to the -9th per cu cm which are at distances between 0.1 pc and 10 pc. Echoes from dust in a circumstellar shell or ejected during a previous eruption will be effectively unobservable.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 327; 347-349
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    The extended atmosphere of Lambda Pavonis at the time of the emergence of H-emissions from minimum intensity (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A study of the Be star Lambda Pavonis, particularly of the changes in the Balmer discontinuity in the interval 1949-1982, is presented. Nearly simultaneous observations carried out with the ESO 1.5 m reflector at La Silla and with the IUE satellite correspond to an epoch when the H emission is starting to increase intensity immediately after having reached its minimum strength. These observations suggest the presence of four distinct regions of line formation, with the material moving outward in the transition region.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 327; 335-341
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  • 45
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    The effect of a hot, spherical scattering cloud on quasi-periodic oscillation behavior (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A Monte Carlo technique is used to investigate the effects of a hot electron scattering cloud surrounding a time-dependent X-ray source. Results are presented for the time-averaged emergent energy spectra and the mean residence time in the cloud as a function of energy. Moreover, after Fourier transforming the scattering Green's function, it is shown how the cloud affects both the observed power spectrum of a time-dependent source and the cross spectrum (Fourier transform of a cross correlation between energy bands). It is found that the power spectra intrinsic to the source are related to those observed by a relatively simple frequency-dependent multiplicative factor (a transmission function). The cloud can severely attenuate high frequencies in the power spectra, depending on optical depth, and, at lower frequencies, the transmission function has roughly a Lorentzian shape. It is also found that if the intrinsic energy spectrum is constant in time, the phase of the cross spectrum is determined entirely by scattering. Finally, the implications of the results for studies of the X-ray quasi-periodic oscillators are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 327; 284-293
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    Effect of line mixing on atmospheric brightness temperatures near 15 microns (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The effect of line mixing on the effective blackbody brightness temperature of the earth in the region of the 15-micron nu 2 Q branch of CO2 is calculated. The procedures used to compute line mixing follow those used to successfully model mixing observed in laboratory spectra of two near-infrared CO2 Q branches. The atmospheric radiances are calculated between 664 and 670/cm, a spectral region that is of interest for sounding the upper troposphere and the stratosphere. Mixing was found to lower the observed brightness temperatures by as much as 3 K for some temperature profiles. Ignoring this effect would significantly impact the ability of advanced sounders to produce temperature retrievals which meet the projected accuracy requirement of 1 K/km.
    Keywords: GEOPHYSICS
    Type: Applied Optics (ISSN 0003-6935); 27; 872-878
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  • 47
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    F region electron temperature signatures of the plasmapause based on Dynamics Explorer 1 and 2 measurements (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A large DE 1 and 2 database covering all local times is used to explore the relationship between electron temperature (Te) signatures in the F region and plamaspheric density structures. The quiet time Te signature remains in the vicinity of 60 deg invariant latitude at all local times, while the plasmapause is found to bulge to about 60 deg at 1500 LT. The plasmasphere in the bulge region is shown to exhibit an internal feature in the vicinity of 60 deg which takes the form of a sharp H(+) gradient. It is suggested that the light-ion gradient may represent a recently created sharp boundary between an old plasmasphere and a new plasmasphere. The present Te characteristics are consisent with plasmasphere depletion and refilling time constants.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1896-190
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    Low-energy bouncing ions in the magnetosphere - A three-dimensional numerical study of Dynamics Explorer 1 data (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1859-187
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    A unidimensional model of comet ionosphere structure (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The one-dimensional continuity and momentum equations for the plasma formed in the expanding coma of a comet near the sun are studied. An analytic expression for the magnetic field configuration in the presence of outflow, photoionization, dissociative recombination, plasma fluid pressure, and friction between the ions and neutrals is obtained. It is suggested that for a Halley-type comet there will be a region sunward of the nucleus from which the magnetic field is excluded, consistent with Giotto observations. Calculations have been performed for Halley and Giacobini-Zinner type comets, and in the field-free regions it is shown that the dominant terms in the momentum equation balancing the magnetic pressure gradient are the ion neutral friction and the net mass loading momentum gain.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1759-176
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    First Viking results - Magnetic field measurements (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The magnetic field experiment on the Swedish Viking satellite consists of a triaxial fluxgate magnetometer system with the sensors mounted on a 2-m boom. Transverse magnetic field perturbations are readily observed which identify the large-scale auroral and cusp-region Birkeland current (BC) systems. A sharp gradient was observed in the dayside region near apogee and 08:40 MLT during a pass on March 25, 1986 which has been interpreted as an earthward-flowing BC of 8 micro-A/sq m. When projected to ionospheric altitudes it is estimated that the current density is 200 micro-A/sq m.
    Keywords: GEOPHYSICS
    Type: Physica Scripta (ISSN 0031-8949); 37; 3, Ma; 479-481
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    The universe at infrared wavelengths (1988)
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    Publication Date: 2011-08-19
    Description: This article discusses the status of infrared astronomy after the mission of the Infrared Astronomical Satellite (IRAS). Important scientific results from IRAS include: the origin of the interplanetary dust cloud, the formation of solar type stars, the energetics of the interstellar medium, the discovery of ultra-luminous infrared galaxies and their possible relation to the origin of quasars, and the large scale structure of the universe.
    Keywords: ASTROPHYSICS
    Type: (ISSN 0007-084X); 41; 23-34
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    The promise of astrophysical observation conducted from space (1988)
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    Publication Date: 2011-08-19
    Description: The roles of instrumentation and the Space Station in addressing the most important questions in astrophysics are considered. The growth in the power of astronomical instruments over the past several decades is reviewed. Progress that can be made in the coming decades in understanding the origin of the universe, in learning more about quasars, black holes, and the fundamental laws of physics, and in possibly detecting other planetary systems and extraterrestrial life is considered.
    Keywords: ASTROPHYSICS
    Type: (ISSN 0007-084X); 41; 17-22
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    Outgassing asymmetry of periodic comet Encke. I - Apparitions 1924-1984 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A concept of a collimated flow of ejecta from a discrete source (vent) on the surface of a rotating cometary nucleus is applied to P/Encke, based on positional observations of its sunward fanlike coma at 13 apparitions between 1924 and 1984. The major results include a finding that the observations are consistent with an invariable position of the rotation pole during the 60 yr (yielding an obliquity of 70 deg), although this is not to be interpreted as an indication that the nucleus is not precessing. Two vents are identified on the nucleus surface: one on the northern hemisphere at a latitude of +55 deg, of an estimated sublimitation area of 0.4 sq km, which is active along the inbound leg of the comet's orbit until a few days preperihelion and again beginning several weeks postperihelion; the other on the southern hemisphere at -75 deg, of an estimated area of 0.6 sq km, whose activity prevails in the intervening time. There appears to be a significant difference between the two regions in terms of dust content in their emissions.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 95; 911-924
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    Detection of the 2(20) to 2(21) transition of HDO in Orion A - Evidence for dense clumped gas in the hot core (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Results of the first detection of the 10.3 GHz 2(20) to 2(21) transition of HDO in Orion A are presented. Two components of OMC-1 have been identified, a hot core and a spike component associated with the compact molecular ridge cloud. The hot core is modeled as having an effective radiation temperature of 350 K and an HDO column density of 8 x 10 to the 16th/sq cm. The spike component is best fitted by a column density in HDO of about 6 x 10 to the 15th/sq cm. The present data are consistent with clumping and with cloud collision models of maser excitation.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 326; 376-383
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    X-ray spectral models of Galactic bulge sources - The emission-line factor (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Current difficulties in finding unique and physically meaningful models for the X-ray spectra of Galactic bulge sources are exacerbated by the presence of strong, variable emission and absorption features that are not resolved by the instruments observing them. Nine Einstein solid state spectrometer (SSS) observations of five Galactic bulge sources are presented for which relatively high resolution objective grating spectrometer (OGS) data have been published. It is found that in every case the goodness of fit of simple models to SSS data is greatly improved by adding line features identified in the OGS that cannot be resolved by the SSS but nevertheless strongly influence the spectra observed by SSS.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 326; 186-193
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    Cosmic string induced peculiar velocities (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper considers the scenario of a flat universe with a network of heavy cosmic strings as the primordial fluctuation spectrum. The joint probability of finding streaming velocities of at least 600 km/s on large scales and local peculiar velocities of less than 800 km/s is calculated. It is shown how the effects of loops breaking up and being born with a spectrum of sizes can be estimated. It is found that to obtain large-scale streaming velocities of at least 600 km/s, it is necessary that either a large value for beta G mu exist or the effect of loop fissioning and production details be considerable.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 326; 70-76
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    Oxygen chemistry of shocked interstellar clouds. III - Sulfur and oxygen species in dense clouds (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The chemical evolution of oxygen and sulfur species in shocked dense clouds is studied. Reaction rate constants for several important neutral reactions are examined, and revised values are suggested. The one-fluid magnetohydrodynamic shock structure and postshock chemical evolution are calculated for shocks of velocity v(s) = 10 km/s through clouds of initial number density n(0) = 100,000/cu cm and of molecule/atom ratios H2/H = 10, 1000, and 100,000 with most sulfur contained initially in molecules SO2 and SO. Abundances of SO2, SO, CS, and OCS remain near their preshock values, except in clouds containing substantial amounts of atomic hydrogen, where significant destruction of sulfur-oxygen species occurs. Abundances of shock-enhanced molecules HS and H2O are sensitive to the molecule/atom ratio. Nonthermal oxygen-hydrogen chemistry has a minor effect on oxygen-sulfur molecules in the case H2/H = 10.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 325; 411-416
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    String-driven inflation (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It is argued that, in fundamental string theories, as one traces the universe back in time a point is reached when the expansion rate is so fast that the rate of string creation due to quantum effects balances the dilution of the string density due to the expansion. One is therefore led into a phase of constant string density and an exponentially expanding universe. Fundamental strings therefore seem to lead naturally to inflation.
    Keywords: ASTROPHYSICS
    Type: Physical Review Letters (ISSN 0031-9007); 60; 549-552
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    Trace gas emissions from a mid-latitude prescribed chaparral fire (1988)
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    Publication Date: 2011-08-19
    Description: Smoke-plume gas samples were collected at altitudes from 35-670 m above the ground over the San Dimas Experimental Forest during a 400-acre prescribed chaparral fire. Mean emission ratios relative to CO2 for CO, H2, CH4, and total nonmethane hydrocarbons were lower than previous values obtained for large biomass-burning field experiments. Comparison of samples from vigorously flaming and mixed stages of combustion revealed little differences in CO2 normalized emission ratios for these gases (except for N2O).
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1653-165
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    Measurements of odd nitrogen compounds in the stratosphere by the ATMOS experiment on Spacelab 3 (1988)
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    Publication Date: 2011-08-19
    Description: Spacelab 3's Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment has obtained 30 deg N and 48 deg S vertical profiles of reservoir gases, source gases, and other trace molecules that are important in the middle atmosphere's odd nitrogen, odd chlorine, and odd hydrogen chemical families. The abundances of individual gases and total odd nitrogen levels measured by ATMOS have been compared with prior results obtained from balloon and satellite platforms. The lower-limit profile agrees with ATMOS data to within 16 percent up to 42 km altitude.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1718-173
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    Measurements of atmospheric hydrocarbons and biogenic emission fluxes in the Amazon boundary layer (1988)
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    Publication Date: 2011-08-19
    Description: Tropospheric mixing ratios of methane, C2-C10 hydrocarbons, and carbon monoxide were measured over the Amazon tropical forest near Manaus, Amazonas, Brazil, in July and August 1985. The measurements, consisting mostly of altitude profiles of these gases, were all made within the atmospheric boundary layer up to an altitude of 1000 m above ground level. Data characterize the diurnal hydrocarbon composition of the boundary layer. Biogenic emissions of isoprene control hydroxyl radical concentrations over the forest. Biogenic emission fluxes of isoprene and terpenes are estimated to be 25,000 micrograms/sq m per day and 5600 micrograms/sq m per day, respectively. This isoprene emission is equivalent to 2 percent of the net primary productivity of the tropical forest. Atmospheric oxidation of biogenic isoprene and terpenes emissions from the Amazon forest may account for daily increases of 8-13 ppb for carbon monoxide in the planetary boundary layer.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1407-141
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    Elemental abundance analyses with coadded Dominion Astrophysical Observatory spectrograms. III - The superficially normal standard stars Theta Leonis, Tau Herculis and Omicron Pegasi (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 230; 671-694
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    Luminosity excesses in low-mass young stellar objects - A statistical study (1988)
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    Publication Date: 2011-08-19
    Description: This paper presents a statistical study in which the observed total luminosity is compared quantitatively with an estimate of the stellar luminosity for a sample of 59 low-mass young stellar objects (YSOs) in the Taurus-Auriga complex. In 13 of the analyzed YSOs, luminosity excesses greater than 0.20 are observed together with greater than 0.6 IR excesses, which typically contribute the bulk of the observed excess luminosity and are characterized by spectral energy distributions which are flat or rise toward long wavelengths. The analysis suggests that YSOs showing the largest luminosity excesses typically power optical jets and/or molecular outflows or have strong winds, as evidenced by the presence of O I emission, indicating a possible correlation between accretion and mass-outflow properties.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 95; 534-542
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    The IRAS Bright Galaxy Sample. III - 1-10 micron observations and coadded IRAS data for galaxies with L(IR) equal to or greater than 10 to the 11th solar luminosities (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper presents the results of 1-10-micron observations and coadded IRAS data on 61 galaxies from the Bright Galaxy Sample, with IR luminosities, L(IR), equal to or greater than 10 to the 11th solar luminosities. It was found that an increase in the total L(IR) above 10 to the 11th solar luminosity is correlated with increased emission from hot dust with characteristic temperatures about 800 K. This hot dust contributes a substantial fraction of the 2.2- and 3.7-micron emission, resulting in a greatly increased dispersion in R(3.7/1.6) and R(2.2/1.6) for these high-luminosity galaxies, relative to lower-luminosity galaxies. This excess hot-dust emission appears to 'turn on' at luminosities of about 10 to the 11th solar luminosity. The spatial distribution of the 10-micron emission indicated a substantial extended component for most of the galaxies in this sample, implying that star-formation processes contribute significantly to the luminosities.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 95; 356-373
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    The stellar composition of X-ray surveys from the Einstein Observatory (1988)
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    Publication Date: 2011-08-19
    Description: A new class of X-ray-luminous 'yellow' stellar objects which contributes significantly to the stellar log N-log S distribution, but which cannot be reconciled with normal G and K main-sequence stars. This identification results from a new analysis of the stellar content of three samples of X-ray-selected X-ray sources observed with the Einstein Observatory, namely the 'Medium Sensitivity Survey', the 'High Sensitivity Survey', and the 'Hyades Region Survey'. In this paper, both X-ray and optical properties of the stellar samples in these surveys are reported. The actual stellar content of the surveys is compared with predictions based on current knowledge of stellar X-ray luminosity functions and the stellar composition and spatial distribution in the Galaxy. It is shown that a plausible identification for the excess population of 'yellow' stars is with the active, RS CVn-like binaries.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 324; 1010-101
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    Survey of low-frequency electromagnetic waves stimulated by two coexisting newborn ion species (1988)
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    Publication Date: 2011-08-19
    Description: Parallel electromagnetic instabilities generated by coexisting newborn hydrogen and oxygen ions are studied for different orientations of the interplanetary magnetic field with respect to the solar wind velocity. The wave growth dependence on the densities and temperatures of the newborn species is investigated. The results indicate that in most domains of the Brillouin plane each ion beam can excite resonant instabilities without undue influence from the other newborn ion species. Although comparable resonant instabilities are more efficiently generated by the lighter newborn ions in ion-rich environments, the growth stimulated by the heavier species can withstand large beam density decreases.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 48-58
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    Nonlinear evolution of the Kelvin-Helmholtz instability in the high-latitude ionosphere (1988)
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    Publication Date: 2011-08-19
    Description: The first numerical simulations of the nonlinear evolution of the electrostatic Kelvin-Helmholtz (K-H) instability with ionospheric Perderson conductivity coupling are presented. It is found that the K-H instability develops in a distinctly different manner in the nonlinear regime with Pedersen coupling than without it. Pedersen coupling effects, in conjunction with a neutral wind and density gradient, are shown to result in an increased time scale for K-H instability wave growth, to inhibit K-H vortex formation, to lead to nonlinear structures which can be described as 'breaking waves', and to generate, in the nonlinear regime, small-scale turbulence by means of secondary instabilities growing on primary waves. The spatial power spectra of the electrostatic potential and density fluctuations are computed, and differences with and without Pedersen effects are reported.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 137-152
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    Abundance effects on the Cepheid distance scale (1988)
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    Publication Date: 2011-08-19
    Description: A new investigation of the dependence of the period-luminosity (PL) and period-luminosity-color (PLC) relations on the helium and metal abundances in classical Cepheids is presented. Composition dependences are assigned to all quantitites under study, so that the results represent a true theoretical prediction. It is found that the PLC relation in B,V magnitudes is at least five times more sensitive to chemical composition than is the PL relation. If the PL relation is adopted and the helium abundance is held fixed, a Cepheid with Z = 0.005 should be fainter than one with Z = 0.02 by about 0.04 mag. Since the slope of the predicted PL relation is independent of chemical composition, the PL relation can be considered to be effectively universal. Additional supporting observational evidence is described, and theoretical results are also presented for the bolometric PL relation, whose slope and dependence on metal abundance should be roughly applicable to infrared observations of Cepheids.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 329; 712-719
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    Nucleus of Comet IRAS-Araki-Alcock (1983 VII) (1988)
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    Publication Date: 2011-08-19
    Description: Optical, radar, infrared, UV, and microwave-continuum observations of Comet IRAS-Araki-Alcok were obtained in May 1983, the week of the comet's close approach to earth. The comet has a nucleus dimension and a rotation period which are similar to those of Comet Halley, but a different morphological signature (a persisting sunward fan-shaped coma). Time variations are noted in the projected nucleus cross section. Results suggest significant limb-darkening effects in the relevant domains of radio waves, and that the comet's interior must be extremely cold. It is found that the thermal-infrared fluxes from the inner coma of the comet are dominated by the nucleus.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 95; 1876-189
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    The role of molecular hydrogen and methane oxidation in the water vapour budget of the stratosphere (1988)
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    Publication Date: 2011-08-19
    Description: The detailed photochemistry of methane oxidation has been studied in a coupled chemical/dynamical model of the middle atmosphere. The photochemistry of formaldehyde plays an important role in determining the production of water vapor from methane oxidation. At high latitudes, the production and transport of molecular hydrogen is particularly important in determining the water vapor distribution. It is shown that the ratio of the methane vertical gradient to the water vapor vertical gradient at any particular latitude should not be expected to be precisely 2, due both to photochemical and dynamical effects. Modeled H2O profiles are compared with measurements from the Limb Infrared Monitor of the Stratosphere (LIMS) experiment at various latitudes. Molecular hydrogen is shown to be responsible for the formation of a secondary maximum displayed by the model water vapor profiles in high latitude summer, a feature also found in the LIMS data.
    Keywords: GEOPHYSICS
    Type: Royal Meteorological Society, Quarterly Journal (ISSN 0035-9009); 114; 281-295
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    ISEE-3 observations of the earth's radio continuum through the bow shock and magnetosheath and in the magnetosphere (1988)
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    Publication Date: 2011-08-19
    Description: On October 1 1983, ISEE-3 crossed the earth's bow shock several times and entered the magnetosphere while continuously recording the nonthermal continuum (NTC) radio emission which is generated inside the magnetosphere. The effects of the solar wind, the bow shock, the magnetosheath, and the magnetopause on the propagation of the NTC are studied. On that day it is found that: (1) the relative values of the NTC low frequency cut-off in the solar wind and in the magnetosheath is due to an unusually high density overshoot in the bow shock, 7 to 11 times the solar wind density; (2) refraction at the interface between the magnetosheath and the solar wind can explain most of the decrease in the source angular size when the observer travels away from the earth; (3) plasma density irregularities in the magnetosheath cause considerable scattering of the NTC, and this effect gives a large apparent size to the NTC source when observed from inside the magnetosheath; and (4) the apparent source is also relatively large inside the magnetosphere, probably due to an approach to ray isotropy caused by oblique reflections from the magnetopause.
    Keywords: GEOPHYSICS
    Type: Annales Geophysicae (ISSN 0980-8752); 6; 309-318
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    Long-term temporal variability of Cygnus X-2 (1988)
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    Publication Date: 2011-08-19
    Description: Observations of the low-mass binary X-ray source Cyg X-2 taken over a five-year period using instruments on OSO 8, HEAO 1, and Einstein are presented. Irregular changes in intensity of up to 60 percent on time scales ranging from minutes to days are seen. The source appears to have long-term low-luminosity states during which dips lasting about three days occur. When these long dips occur, they always appear at the same phase in the optically determined 9.8-day orbital period. There are three distinct types of short-term dips distinguished by differing correlations between spectral hardness and intensity.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 329; 276-289
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    Aerodynamic properties of fractal grains - Implications for the primordial solar nebula (1988)
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    Publication Date: 2011-08-19
    Description: Gas-grain and grain-grain interactions have a significant role in the evolution of the primordial solar nebula. There is also compelling evidence for larger grains in dense interstellar clouds than in the diffuse interstellar medium. In the usual treatments of grain collisions, where it is assumed that collisions produce compact bodies with a constant density, the gas drag decreases rapidly with size. The first step toward a quantitative analysis of the aerodynamic behavior of fractal aggregates is reported here, and it is shown that for fractals drag decreases very slowly.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 329; L39-L41
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    New evidence from the South China Sea for an abrupt termination of the last glacial period (1988)
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    Publication Date: 2011-08-19
    Description: Results demonstrating an abrupt change in the rate and character of sedimentation in the South China Sea at the close of the last glacial period are presented. Radiocarbon dating and its position in the oxygen isotope shift suggest that this change may be coincident with the abrupt change in climatic conditions seen at high latitudes in the North Atlantic and the Antarctic at 13 kyr BP. These results support the contention that a major global climatic change occurred between 14 and 13 kyr BP.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 333; 156-158
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    Comparison of OGO 6 measured thermospheric temperatures with the MSIS-86 empirical model (1988)
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    Publication Date: 2011-08-19
    Description: The thermospheric temperatures measured by the Fabry-Perod interferometer on the OGO 6 satellite are found to be reasonably represented by the mass spectrometer/incoherent scatter 1986 (MSIS-86) empirical model except for two anomalies, one in the South Atlantic and the other near noon local time. These anomalies are likely due to measurement problems. The OGO 6 temperature data were not used in the generation the MSIS models, so this is an independent comparison of measured and model temperatures. The measurements were made primarily during daytime at mid to low latitudes and throughout the day at high latitudes. On average, the measured temperatures are 16 K below the MSIS-86 model temperatures. Latitude gradients during solstices as well as for the yearly average are well represented by the model, as are high-latitude longitudinal and magnetic activity variations.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 5965-597
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    The interaction of supernova 1987A with dense circumstellar gas (1988)
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    Publication Date: 2011-08-19
    Description: The light travel time effects on the evolution of line fluxes, line profiles, and spatial structure of the emission from supernova 1987A are described. Current high spectral resolution observations suggest a lower limit to the age of the shell of 5000 yr and suggest a relatively low shell velocity. The narrow lines are predicted to shift to the red at a rate depending on the shell age. Observations of X-rays below 10 keV by the Ginga satellite are difficult to interpret in terms of circumstellar interaction because of the time variability.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 514-516
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    The influence of supernovae and passing stars on comets in the Oort cloud (1988)
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    Publication Date: 2011-08-19
    Description: It is demonstrated here that the passage of luminous stars through the Oort Cloud over the age of the solar system will subject all comets to heating episodes up to at least 16 K, and a sizeable fraction to 30 K. Stochastic supernovae have even more striking effects during monthlong events; conservative estimates of the supernovae are in the Galactic disk suggest that most comets have been heated to 45 K, and a fraction to about 60 K. These results imply that comets are not fully pristine relics of solar system formation.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 407-411
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    Probes of large-scale structure in the universe (1988)
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    Publication Date: 2011-08-19
    Description: A general formalism is developed which shows that the gravitational instability theory for the origin of the large-scale structure of the universe is now capable of critically confronting observational results on cosmic background radiation angular anisotropies, large-scale bulk motions, and large-scale clumpiness in the galaxy counts. The results indicate that presently advocated cosmological models will have considerable difficulty in simultaneously explaining the observational results.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 328-330
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    Intensity profiles of dust near extended sources on Comet Halley (1988)
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    Publication Date: 2011-08-19
    Description: The dust particle intensity decreases proportional to 1/R from the Comet Halley, as expected for free outflow. Flattening of the profile is evident within several tens of km from the nucleus. It is shown here that these phenomena can be explained by a model that considers the extended size and nonunifomity of the active region on the surface of the cometary nucleus. A critical scale length, defined by the opening angle of a jetlike feature and the size of the source, can be introduced to describe the flattening. The model is consistent with the observations and provides the basis for studying other mechanisms such as particle fragmentation.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 332; 51
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    Nickel, argon and cobalt in the infrared spectrum of SN1987A - The core becomes visible (1988)
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    Publication Date: 2011-08-19
    Description: Infrared spectra of supernova 1987A taken in April and November 1987 are presented, showing two distinctly different stages in the evolution of the expanding gas shell. The optical and infrared spectrum in April originated from the hydrogen envelope and show weak hydrogen lines rising above a 5,000-K photospheric continuum. The November spectrum was dominated by strong emission lines from heavy elements as well as many lines from highly excited levels of hydrogen, with peak flux levels in the lines at or slightly above the level of the continuum in April. It is concluded that the inner regions of the supernova were just becoming visible in early 1988. It is expected that these regions contain heavy elements produced by advanced nuclear burning stages in the progenitor star and in the shock wave that ejected all material external to the iron core.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 331; 505
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    Observation of an ionospheric disturbance caused by a gamma-ray burst (1988)
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    Publication Date: 2011-08-19
    Description: A first observation of an ionospheric disturbance from a gamma-ray burst is reported. The burst, GB30801, occurred at 22:14:18 UT on August 1, 1983, and was one of the strongest ever observed. The total fluence was 0.002 erg/sq cm, most of which occurred in the first 4 s of the burst. Simultaneously, a change was observed in the amplitude of a VLF radio signal from a transmitter in Rugby, England indicative of an ionospheric disturbance. Weaker disturbances were also recorded at the same receiving site on signals from VLF stations in Annapolis, Maryland and Lualualei, Hawaii. The times of the burst and the disturbances are coincident within the 10-s resolution of the VLF recording system. No similar disturbances were observed within 60 hr around the time of the burst. In the future, a network of VLF burst monitors may provide measurements of the total ionizing energy fluence from a burst, as well as some limited directional information.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 331; 418-420
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    Gravity domains and assembly of the North American continent by collisional tectonics (1988)
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    Publication Date: 2011-08-19
    Description: A gravity trend map of North America, based on a horizontal Bouguer gravity gradient map produced from gravity data for Canada and the conterminous United States, is presented and used to define a continental mosaic of gravity trend domains akin to structural domains. Contrasting trend characteristics at gravity domain boundaries support the concept of outward growth of the continent primarily by accretionary tectonics. Gravity patterns, however, indicate a different style of tectonics dominated in the development of now-buried Proterozoic orogenic belts in the south-central United States, supporting a view that these belts formed along the leading edge of a southward-migrating Proterozoic continental margin.
    Keywords: GEOPHYSICS
    Type: Nature (ISSN 0028-0836); 331; 333
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    Atmospheric ozone at South Pole, Antarctica, in 1986 (1988)
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    Publication Date: 2011-08-19
    Description: Results of NOAA's measurements of the ozone vertical distributions at the South Pole and of the annual course of total ozone, conducted in 1986 with balloon-borne electrochemical concentration cell (ECC) ozonesondes and a Dobson spectrophotometer, are described. The major finding was that the stratospheric ozone decreases abruptly between September 20 and October 15, with the bulk decrease occurring between 12 and 21 km. In this period, the column ozone and ozone volume mixing ratio at 16 km (the altitude of the normal ozone maximum at South Pole) decreased by 78 percent, and column ozone between 12 and 21 km decreased by 50 percent. The results of these measurements are compared with data obtained in 1971, and the changes observed in the ozone vertical distributions and in the temporal variations of atmospheric ozone are discussed.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 5167-518
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    Neutral stellar winds that drive bipolar outflows in low-mass protostars (1988)
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    Publication Date: 2011-08-19
    Description: The Arecibo radio telescope at the 21-cm line of atomic hydrogen has been used to detect a neutral atomic wind in the bipolar flow source HH 7-11. An atomic mass of about 0.015 solar associated with the rapidly flowing gas is deduced. The stellar mass-loss rate is roughly 3 x 10 to the -6th solar mass/yr if the crossing time of the decelerating wind is 5000 yr. The excess emission in the H I line core gives a total duration of the outflow of about 70,000 yr. A detailed analysis of the H I line shape yields a reasonable deceleration rate for the atomic wind if the stellar wind continuously entrains ambient molecular gas as it propagates from the protostar. A stellar wind with the described characteristics and a terminal velocity of 170 km/s would be more than sufficient to drive the known extended CO bipolar outflow in HH 7-11.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 328; 763-776
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    Simultaneous measurement of minor stratospheric constituents with emission far-infrared spectroscopy (1988)
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    Publication Date: 2011-08-19
    Description: The vertical mixing ratio profiles of H2O, HDO, O3, heavy ozone, HF, HCl, HCN, and OH in the stratosphere are retrieved from high-resolution far-infrared emission spectra. These spectra were obtained with a balloon-borne Fourier transform spectrometer in the spring of 1979 at 32 deg N. The nonlinear least squares fit method is used in the analysis. The results are obtained relative to the O2 mixing ratio, whose emission features can be found in the same spectra. The retrieval of OH together with other species should be particularly significant for the study of upper stratospheric photochemistry, although the errors are relatively large: 28 percent for OH and 16-19 percent for other species.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 3851-386
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    Antarctic springtime ozone depletion computed from temperature observations (1988)
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    Publication Date: 2011-08-19
    Description: An observationally based, mechanistic dynamical model is used to simulate the decline of total ozone during September and October for the years 1979 through 1986. Vertical velocities derived from observed stratospheric temperature changes and computed radiative heating rates are used to advect an ozone mixing ratio profile during the Antarctic spring period. An early August 1982 Syowa balloonsonde ozone profile is used to initialize the computations. The model reasonably simulates the September and October changes in total ozone, considering the uncertainties in the observed data and the radiative heating. The simulated decline is found to be very sensitive to the choice of initial ozone profile and to small changes in the radiative heating. The results of this study suggest that the dynamical hypothesis of the Antarctic ozone depletion is both quantitatively credible and consistent with the observed temperature changes.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 3833-384
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  • 87
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    The difference in hydrogen abundance between two classes of type I X-ray bursts (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The hypothesis that the bright type I X-ray bursts differ from faint bursts in that a hydrogen-rich envelope is ejected in the former type and not in the latter is theoretically discussed and experimentally investigated. Color-temperature versus luminosity diagrams of X-ray bursts from MXB 1636-536 and MXB 1608-522 are constructed based on observations from the Tenma satellite and are used to study the hydrogen richness of the surface of the neutron stars resulting from the outbursts. Systematic differences between the bright and faint class diagrams are found which confirm the hypothesis.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 328; 251-255
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  • 88
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    The bipolar outflow from the rotating carbon star, V Hydrae (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A high-resolution optical spectrum of the mass-losing red giant carbon star, V Hya, has been obtained, and the (C-12)O (J = 1-0) millimeter emission in the circumstellar envelope around this star has been mapped. It is found that the CO emission is extended, clearly anisotropic and can be interpreted as the superposition of an isotropic emission with that of a bipolar flow. The optical spectrum of the photosphere suggests that this star is rotating with v sin i between 10 and 20 km/s. These data are interpreted, together, to suggest that the bipolar nature of the outflow results from the flattening of the star induced by its rapid rotation.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 328; L25-L28
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  • 89
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    Mass loss from rapidly rotating magnetic protostars (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It is proposed that bipolar outflows from young stellar objects originate from a protostar rotating at breakup at its equator because it is being spun up by an adjoining accretion disk. Mass outflow at an appreciable fraction of the infall rate from a surrounding molecular cloud core onto the star and disk can be driven centrifugally if the protostar has a sufficiently strong magnetic field. The expansion of the flow toward the rotational poles may provide a collimation mechanism for focusing an ordinary stellar wind into optical jets.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 328; L19-L23
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  • 90
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    Dual-frequency and dual-polarization VLBI observations of the stellar system Algol (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Results of multiepoch VLBI observations of the stellar system Algol are presented, including dual-polarization and dual-frequency measurements at 2.3 and 8.4 GHz. The brightness temperature of the radio source is generally between 3 x 10 to the 8th K and 5 x 10 to the 9th K and is consistent with gyrosynchrotron emission from energetic electrons with mean energy less than 1 MeV in an active coronal region. Two exceptional events were observed: a high-brightness, broad-band outburst occurring simultaneously at 2.3 and 8.4 GHz, and a short-duration, highly polarized and high-brightness temperature outburst at 1.66 GHz. A simple physical model which includes all three types of emission is suggested.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 328; 232-242
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  • 91
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    Classical bump Cepheids - Reconciliation of theory with observations (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: New models of classical bump Cepheids lying along the Cepheid ridge line in the H-R diagram are computed to obtain a more accurate set of predicted surface velocity curves. Acceptable Cepheid models are found to be 0.5 mag brighter at a fixed stellar mass than standard evolutionary models. All the previously obtained manifestations of the Cepheid mass discrepancy, except for the anomalous double-mode Cepheid masses, are resolved, at least in a statistical sense, by accepting the implied luminosity increase. The need for the luminosity increase is independently inferred from standard evolutionary models of intermediate-mass and high-mass giant and supergiant stars from their location in the observational H-R diagram.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 328; 196-206
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  • 92
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    H2 and H I emission line imaging of the ring nebula (NGC 6720) (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Infrared emission-line images of the v = 1-0 S(1) transition of molecular hydrogen and Br-gamma recombination line of atomic hydrogen which cover the entire extent of NGC 6720, the Ring nebula. The maps presented here are the highest angular resolution images of these transitions yet produced for this object and have very low relative positional uncertainty. As a result, the spatial stratification of the ionized and shocked molecular zones within the nebula is clearly resolved. These data, and data from the Infrared Astronomical Satellite, are used to determine the H2, H I, and dust mass within the nebula. Energy sources for the dust heating, formation and destruction of the H2, and overall evolution of the nebula are also discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 325; 604-609
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  • 93
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    Cosmic string wakes and large-scale structure (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The formation of structure from infinite cosmic string wakes is modeled for a universe dominated by cold dark matter (CDM). Cross-sectional slices through the wake distribution tend to outline empty regions with diameters which are not inconsistent with the range of sizes of the voids in the CfA slice of the universe. The topology of the wake distribution is found to be spongy rather than cell-like. Correlations between CDM wakes do not extend much beyond a horizon length, so it is unlikely that CDM wakes are responsible for the correlations between clusters of galaxies. An estimate of the fraction of matter to accrete onto CDM wakes indicates that wakes could be more important in galaxy formation than previously anticipated.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 325; 521-530
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  • 94
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    Resonant geomagnetic field oscillations and Birkeland currents in the morning sector (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The relationship between large-scale Birkeland currents and resonant oscillations of the geomagnetic field is investigated on the basis of Viking magnetic-field, electric-field, and particle measurements and AMPTE-CEE and IMP-8 magnetic-field measurements obtained during April 23-25, 1986. The data are presented in extensive graphs and characterized in detail. The 3-16-mHz 5-60-nT magnetic-field oscillations detected by Viking are also seen by AMPTE-CEE below L = 8.8 and extend from the lower L shells to the boundary between regions 1 and 2 of the Birkeland-current system, and this boundary is shown to be closely related to the interface between the low-latitude boundary layer and the central plasma sheet. It is suggested that the magnetospheric oscillations may be driven by several different solar-wind features, possibly depending on the direction of the IMF.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 2661-267
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  • 95
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    Interplanetary magnetic field draping about fast coronal mass ejecta in the outer heliosphere (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The possibility that the IMF becomes draped around coronal mass ejections (CMEs) propagating rapidly through the quiescent solar wind into the outer heliosphere is investigated theoretically. The results are presented in diagrams and graphs and discussed in detail. It is found that large sunward-directed structures analogous to the Venus and cometary magnetotails should form when the CME velocity exceeds the solar-wind velocity by more than the local Alfven speed; such structures could hang up swept-up IMF flux for as long as several days. Pioneer 11 magnetic-field measurements at 6.9-9.4 AU from three 20-d periods in 1978 are examined and shown to contain some features consistent with CME draping.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 2519-252
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  • 96
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    A few parts in 10 to the 8th geodetic baseline repeatablity in the Gulf of California using the Global Positioning System (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: GPS geodetic measurements of 350-650 km baselines across the Pacific-North America plate boundary in the Gulf of California are presented. The analysis employs a four-station U.S. fiducial network and combined carrier phase and pseudorange data. Water vapor radiometer data at the Gulf sites are used to calibrate the GPS signal for wet tropospheric path delays. Residual tropospheric delays are modeled as first-order exponentially correlated stochastic processes. The measurement precision for horizontal components is a few parts in 10 to the 8th or better.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 353-356
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  • 97
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    Iridium abundance maxima in the Upper Cenomanian extinction interval (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Two iridium abundance peaks, both 0.11 ppb (whole-rock basis) over a local background of 0.017 ppb, have been found in Middle Cretaceous marine rocks near Pueblo, Colorado. They occur just below the 92-million-year-old Cenomanian-Turonian (C-T) stage boundary. No other peaks were found in 45 meters of strata (about 2.5 million years of deposition) above and below the boundary interval. The broad lower peak straddles the first in a series of extinctions of benthic and nektonic macrobiota which comprise the C-T extinction event. The sharp upper peak occurs stratigraphically about 1.2 meters above the lower peak. The excess Ir might be from meteoroid impacts.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 15; 346-349
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  • 98
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    Mass loss from S stars (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The mass-loss process in S stars is studied using 65 S stars from the listing of Wing and Yorka (1977). The role of pulsations in the mass-loss process is examined. It is detected that stars with larger mass-loss rates have a greater amplitude of pulsations. The dust-to-gas ratio for the S stars is estimated as 0.002 and the average mass-loss rate is about 6 x 10 to the -8th solar masses/yr. Some of the properties of the S stars, such as scale height, surface density, and lifetime, are measured. It is determined that scale height is 200 pc; the total duration of the S star phase is greater than or equal to 30,000 yr; and the stars inject 3 x 10 to the -6th solar masses/sq kpc yr into the interstellar medium.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 66; 33-41
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  • 99
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    Boundary layer ozone - An airborne survey above the Amazon Basin (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Ozone data obtained over the forest canopy of the Amazon Basin during July and August 1985 in the course of NASA's Amazon Boundary Layer Experiment 2A are discussed, and ozone profiles obtained during flights from Belem to Tabatinga, Brazil, are analyzed to determine any cross-basin effects. The analyses of ozone data indicate that the mixed layer of the Amazon Basin, for the conditions of undisturbed meteorology and in the absence of biomass burning, is a significant sink for tropospheric ozone. As the coast is approached, marine influences are noted at about 300 km inland, and a transition from a forest-controlled mixed layer to a marine-controlled mixed layer is noted.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1452-146
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  • 100
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    Tropospheric nitric oxide measurements over the Amazon Basin (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Horizontal and vertical distributions of nitric oxide (NO) were measured over the Amazon Basin during NASA's Global Tropospheric Experiment (GTE) Amazon Boundary Layer Experiment mission in July-August 1985. During transit flights between the Virginia coast and Manaus, Brazil, NO mixing ratios were 12-15 pptv at 5 km altitude. Values up to 200 pptv were observed in electrically active clouds. During longitudinal surveys over the Amazon region, NO mixing ratios in the lower planetary boundary layer decreased from 25-60 pptv over the central basin to 10-12 pptv in coastal regions. In the convective cloud layer or free troposphere, NO mixing ratios averaged 13 pptv in regions not influenced by biomass burning. No longitudinal trend above the mixed layer could be detected. A steep negative gradient with increasing altitude was noted within the mixed layer before midday. Mixing ratios decreased from 60 pptv at 0.2 km to about 15 pptv at the top of the mixed layer (1 km). By midday, growth of the mixed layer height and enhanced mixing reduced the gradient, and evidence for mixing of NO into the convective cloud layer was noted.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 1396-140
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