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  • SOLAR PHYSICS  (256)
  • 1995-1999
  • 1980-1984
  • 1975-1979  (256)
  • 1925-1929
  • 1978  (256)
Collection
Keywords
Years
  • 1995-1999
  • 1980-1984
  • 1975-1979  (256)
  • 1925-1929
Year
  • 1
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    European Space Agency studies of the solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The feasibility and scientific objectives of a solar probe were studied by a Mission Definition Group in 1975 and 1976. The orbit analysis program was developed and an extended study of the orbit analysis was done in 1977. The results of these studies are in the Report of the Mission Definition Study (1976) and an E.S.O.C. report (1978), and the reader is referred to these sources for greater details. In this report, only brief discussion on mission concept and objectives, satellite design, orbit, orbit analysis, are presented.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 556-564
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  • 2
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    Solar probe study (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Realistic options for a Solar Probe Mission consistent with known technical, fiscal, and programmatic constraints are identified. A program plan for NASA which includes identification of necessary research and development activities is developed. A baseline mission and a strawman spacecraft design were selected and used to determine the feasibility of meeting the mission requirements and the sensitivity to variations in those requirements.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 521-534
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  • 3
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    Detection of gravitational radiation and oscillations of the sun via Doppler tracking of spacecraft (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The magnitude of Doppler signals produced by gravitational wave burst, continuous gravitational waves, and oscillations of the sun interacting with a spacecraft are considered. Expressions are worked out for the appropriate noise entering each measurement. The noise sources considered are the Doppler extractor, fluctuations in the solar wind and the troposphere, and fluctuations in the reference oscillator.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 498-517
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  • 4
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    Gravitational wave detection with the solar probe. II. The Doppler tracking method (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: How gravitational radiation affects Doppler tracking is briefly described. The status of the analyses of the sensitivities achievable with the NASA-JPL Deep Space Network(DSN) is given.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 441-449
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  • 5
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    What is the fate of interplanetary dust (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The following general picture of the interplanetary dust is presented: (1) size distribution; (2) spatial distribution; (3) composition; (4) dynamics; and (5) origin. The solar probe mission provides a unique opportunity to study the evolution of the interplanetary dust and its eventual destruction near the sun. Two destructive processes (fragmentation and vaporization) of interplanetary dust are discussed.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 411-419
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  • 6
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    The solar probe and coronal dynamics (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The discovery of coronal holes led to basic changes in ideas about the structure of the low corona and its expansion into the solar wind. The nature of the energy flux is not understood. Current ideas include enhanced thermal conductivities, extended MHD wave heating, and wave momentum transfer, all in rapidly diverging geometries. There is little feel for the relative importance of these processes. The Solar Probe, with its penetration deep into the solar corona, could lead to observational constraints on their relative importance, and thus to an understanding of the origin of the solar wind. Observations from the Solar Probe will also bear on such questions as to whether small scale "intrastream" structure is common close to the Sun in open field-line regions, whether the properties of the wind are pronouncedly different over closed and open field-line regions at five solar radii, and many others. The resolution of these questions requires measurements of the magnetic field and of the proton and electron distribution functions.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 318-333
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  • 7
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    Plasma waves near the sun: Advances possible with a solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A review is presented of current experimental and theoretical knowledge of plasma waves in the solar wind, with comments on the scientific importance of obtaining plasma wave measurements in the region near the sun with the solar probe. The waves discussed include the acoustic waves and shocks which are thought to be the primary source for heating the solar corona, Alfven waves, ion-cyclotron waves, whistler-mode turbulence, ion-acoustic waves, and electron plasma oscillations associated with solar radio emissions. A discussion is presented of the types of measurements which would be needed to study these waves on the solar probe, the constraints imposed on the spacecraft and the research and development which would be needed to provide the necessary instrumentation.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 281-317
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  • 8
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    Probing the solar corona with energetic particles (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Representative sets of recent experimental results and theoretical studies are summarized to show the current knowledge of energetic particle phenomena based mainly on observations near 1 AU. Measurements close to the sun of quantities such as particle spectra, charge and isotopic composition, and the flow of particles as a function of time, together with measurements of the plasma, magnetic field, X-rays, and gamma rays will not only reveal the properties of the source region and acceleration mechanisms but will also provide a better knowledge of the physics of the corona. These measurements may also reveal the existence of large scale inhomogeneities in the solar corona. The general requirements for making these measurements on the solar probe are listed. An energetic particle detector system which has the capability of resolving the charge and isotopic composition up to 50 MeV/nucleon may successfully measure the above quantities provided that it can perform under both very low and average intensity levels.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 205-218
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  • 9
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    Multicolor imaging and photopolarimetry: Disk features, K and F coronas, zodiacal light (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The unique vantage points and viewing geometries afforded by a close-in solar probe are briefly examined with regard to line and continuum measurements of features on the solar disk, the K and F coronas, and the zodiacal light. Common instrument and observing requirements are identified, suggesting that a single instrument could provide much of the necessary observational data on these phenomena.
    Keywords: SOLAR PHYSICS
    Type: JPL A Closeup of the Sun; p 143-154
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  • 10
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    Ion drive performance and trajectories (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The use of Solar Electric Propulsion (SEP) for the Solar Probe Mission is addressed. The dependence of the payload mass on the site of the SEP and the flight time are described on the basis of preliminary data. The range of hardware expected to be available in the 1980's is summarized. There are several classes of optimal low-thrust trajectories for the Solar Probe Mission. These are trajectory types A, B, C corresponding to one, two, or three orbital revolutions, respectively. Plots of transfer trajectories corresponding to type-A, type-A with a Venus Swingby, type-B, and type-C with ab Icarus Rendezvous are shown. A summary of the SEP performance is given.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 544-555
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  • 11
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    Zodiacal light dynamics experiment: A wideband imaging Fabry-Perot interferometer (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The Solar Probe will provide an ideal platform from which to study dynamics of dust particles near the sun by measuring the detailed character of the Fraunhofer structure of the zodiacal light. The suggested instrument is a wideband imaging Fabry-Perot interferometer with state of the art technology in both the optics and the detector. The instrument would function as a high-resolution imaging device providing wavelength resolution of 0.03 A over about a 20 A range. The wideband imaging capability would provide sky maps of the zodiacal light on a despun spacecraft without mechanical scanning. The Solar Probe mission would allow the velocity distribution of the dust to be mapped along most of the trajectory of the spacecraft.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 420-429
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  • 12
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    A solar wind experiment for the solar probe mission (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Electron and ion plasma measurements on Solar Probe are important, especially to elucidate the role of coronal holes as sources of the solar wind and to resolve the long debated question of the importance of wave heating within 20 solar radii to the acceleration of the solar wind. Adaptable instruments are required to cover the large dynamic range of parameters between 1 AU and 4 solar radii. The baseline mission would be improved, in some respects, by the addition of a second spacecraft, following the first by a distance of several solar radii. A spinning spacecraft would be satisfactory, but not essential, for the present objectives. Attention should be paid to having the heat shield electrically conducting. An instrument for ion and electron (but no composition) measurements would have a mass of approximately 10 kg, require 8 w of power, and generate data at a maximum rate of approximately 2 kbits/sec.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 345-353
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  • 13
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    Acceleration and heating of the solar wind (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Some of the competing theories of solar wind acceleration and heating are reviewed, and the observations that are required to distinguish among them are discussed. In most cases what is required is measurement of plasma velocity and temperature and magnetic field, as near the sun as possible and certainly inside 20 solar radii; another critical aspect of this question is determining whether a turbulent envelope exists in this inner region, and if so, defining its properties. Plasma and magnetic observations from the proposed Solar Probe mission would thus yield a quantum jump in our understanding of the dynamics of the solar wind.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 334-344
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  • 14
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    On neutrons from the sun (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A survey of all the experiments carried out over the past decade to verify theoretical predictions for the observation of solar neutrons is presented and discussed. The conclusions drawn from this discussion are: (1) the Solar Probe Mission is important in order to discover the low energy neutrons of solar origin; (2) this discovery is likely to carry very useful information about the nature, the locale, the lifetime and the mode of operation of the acceleration processes in the solar atmosphere; and (3) this information will lead to a rapid development of the science of solar meteorology and the more rapid forecasting of solar activity, on a long-term basis.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 262-270
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  • 15
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    Hard X-ray imaging from the solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The solar probe offers a platform with particular advantages for studying solar nonthermal plasma processes via the observations of hard X-radiation from energetic electrons in the chromosphere and corona, these include (1) high sensitivity, (2) a second line of sign (in addition to the earth's) that can aid in three dimensional reconstruction of the source distribution, and, (3) the possibility of correlation with direct measurements of the nonthermal particles from the probe itself.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 132-142
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  • 16
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    High resolution stereoscopic X-ray imaging of coronal features during a solar probe flyby (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The possible role of solar probe mission in answering fundamental questions about the structure and heating of coronal loops is examined. The experimental technique consists of imaging 1-10 keV X-rays to give accurate temperature profiles of hot active regions and post-flare loops. A limitation on the interpretation of such pictures is that steroscopic reconstruction of the three dimensional arches requires many lines of sight. This kind of information can be provided only by a rapid solar flyby. In addition, the proximity to the sun will provide useful spatial resolution with compact instrumentation. The pictures thus obtained will provide crucial tests of theoretical models of coronal arches.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 111-117
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  • 17
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    Optical observations of the sun from a solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The spatial resolution of solar surface structure to ultimate limits with simple instrumentation. The logic is simple: a 10 cm aperture telescope at 4 solar radii resolves the equivalent of a five meter telescope in earth orbit. Given the ease of producing a diffraction limited 10 cm telescope and the difficulty of fabricating a diffraction limited 5 meter telescope, the performance of the small telescope could well be better. The telescope described complements planned solar orbiting telescopes in earth orbit and would need only a few arcs seconds of pointing.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 89-91
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  • 18
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    Possible measurements of J sub 2 and the sun's angular momentum with the solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The metric tensor is given for describing the dynamical effects of the sun on a solar probe and the gravitational redshift of a probe-based clock in a covariance analysis for the detectability of the solar quadrupole moment and the solar angular momentum. Unknown parameters were determined by least squares fit to the probe tracking data. A polar orbit was assumed with perihelion at 5 solar radii and with an earth-sun-probe angle of 135 deg at perihelion. Tracking was assumed to be Doppler only, with a basic uncertainity of .1 mm/sec in the radial velocity. A drag-free system which could reduce nongravitational forces below the level of 2 times 10 to the minus 12th power was found necessary to preserve this same level of accuracy. Both one way and two way Doppler were supposed in order to determine the gravitational redshift as well as the pure spacecraft dynamics.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 58-59
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  • 19
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    The analysis of high spatial resolution UV and X-ray images by computational modeling (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Very high resolution stereoscopic images of high temperature loop structures observed at UV and X-ray wavelengths in the solar corona can be used to understand physical processes in the corona. An existing computational model is described and sample results are given to demonstrate that computational modeling of coronal structures can indeed take advantage of very high resolution images. The sample results include the run of temperature and number density along a typical loop and the variation of the differential emission measure with temperature. The integration of the differential emission measure with temperature along a column commensurate with an instrument's spatial resolution is the relevant parameter obtained from UV and X-ray observations. The effects of loop geometry and energy input are examined.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 118-131
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  • 20
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    Determination of the structure and heating mechanisms of coronal loops from soft X-ray observations with the solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: High resolution soft X-ray imaging from the solar probe is justified in terms of the expected scientific returns which include the determination of the temperature and density structure of a coronal loop. The advantages of the grazing incidence telescope over the multiple pinhole camera are discussed. An instrument package is described which includes a grazing incidence mirror, a thermal prefilter, a three position filter wheel and a focal plane detector baselined as an 800 by 800 back-illuminated charge coupled device. The structural assembly together with the data processing equipment would draw heavily on the designs being developed for the Solar Polar Mission.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 94-110
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  • 21
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    Measurement of solar gravitational oblateness with gravity gradiometers (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A very high sensitivity rotating gravity gradiometer onboard the spacecraft is described for measuring the gravitational oblateness of the Sun during a solar probe mission. The proposed instrument would be a self-contained structure in a thermal-vacuum-magnetic shield in the shape of a cross, with a mass of 20 kg and arm length of 1.0 m and thickness of 0.1 m. The sensor inside would have a resonant frequency of 1/30 Hz, a mechanical Q of one million and would use gravitational radiation antenna technology to achieve a sensitivity of 6 x 10 to the minus 8th power Eotvos, which would provide a measurement of the solar oblateness to an accuracy of 1.5 to 6 x 10 to the minus 8th power. The gravity gradiometer will require a spinning spacecraft, so that it will not sense the spacecraft gravity fields, but the gradiometer does not need to be at the spacecraft center of mass, or even on the spacecraft spin axis. Major problem areas to be addressed are demonstration of the instrument sensitivity prior to flight and the measurement and compensation for any residual spacecraft angular rates.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 69-78
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  • 22
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    Comments on the drag-free control of a solar probe relativity mission (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A spacecraft going within 4 solar radii of the Sun experiences an acceleration up to .00005 g from solar radiation pressure, and significant (though smaller) accelerations from the solar wind. To obtain satisfactory information about relativistic effects and the Sun's quadrupole mass coefficient, these non-gravitational accelerations are either measured or compensated out by making the spacecraft drag free. A proof mass inside the spacecraft structure is shielded from the external forces, so that it follows a nearly ideal gravitational orbit, and a control system activates gas jets (or other translational forcers) to make the vehicle follow the mass. The problems are mechanizing the control laws and minimizing extraneous effects such as the self gravitational pull of the spacecraft. The extraneous forces can be averaged in one plane by having a spinning vehicle.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 60-68
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  • 23
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    Possible measurement of the coefficient of the second zonal harmonic of the sun's gravitational field with a solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The use of radio tracking of a solar probe to estimate accurately the coefficient of the second zonal harmonic of the sun's gravitational field was examined. Preliminary results indicate that the coefficient can be estimated with a standard error of 10 to the minus 8th power or less, provided that the probe is equipped with a suitable drag-free system to compensate for the effects of non-gravitational accelerations. For signal paths that pass near the sun, dual-band ranging to the probe can provide the tracking accuracy needed to insure that the standard of error is equal to or less than 10 to minus 8th power. The possibility of achieving such accuracy with a single-band radio uplink and a dual-band downlink is discussed.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 19-41
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  • 24
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    The importance of determining the solar quadrupole moment (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Current theoretical modelling of the sun is in difficulty. Additional observations must be made to place constraints on the plethora of conjectures that have been advanced to explain the low neutrino flux and to guide solar model builders in their search to understand the deep interior of the sun. A determination of the magnitude of the solar quadrupole moment, is one such constraint; it places limits on the density, angular velocity and magnetic field distributions inside the sun.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 11-18
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  • 25
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    The Solar Backscatter Ultraviolet (SBUV) and Total Ozone Mapping Spectrometer (TOMS) experiment (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: The SBUV/TOMS is designed to measure the extraterrestrial ultraviolet solar irradiation and the solar ultraviolet radiation from the earth and its atmosphere. Methods to recover the ozone information from backscattered ultraviolet measurements are described. Mapping of the total ozone and 200 mb height fields is obtained.
    Keywords: SOLAR PHYSICS
    Type: The Nimbus 7 User's Guide; p 175-212
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  • 26
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    Radial and solar cycle variations in the solar wind phase fluctuation spectral index as determined from Voyager 1978 solar conjunction data (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: Columnar spectral index information that has been extracted from a sizable volume of Voyager 1978 solar conjunction Doppler phase fluctuation data is presented. The Voyager 1978 results, when compared to similar information derived from the 1976 Helios and Viking Solar Conjunctions, lead to the following inferences: (1) there has been a significant change in the spectral index from 1976 to 1978; (2) there is continuing evidence that favors a slight (positive) correlation between the spectral index and the solar cycle; and (3) there is little or no evidence in support of a radial variation of the spectral index.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 59-65
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  • 27
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    Ballistic trajectories (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The only ballistic trajectory mode feasible for a close solar probe or for an orbit inclined approximately 90 degrees to the ecliptic is the Jupiter gravity assisted mode. A comparison of the trajectories of the Solar Polar and the Solar Probe Mission for 1983 launches is shown. The geometry of the solar encounter phase is practically the same for the 4.3 year orbit achieved by a Jupiter gravity assist and for a one year orbit. Data describing the geometry of an orbit with perihelion at 4 solar radii and aphelion at Jupiter are listed. The range of apparent directions of the solar wind if it is flowing radially outward from the Sun with a speed of either 150 or 300 km/sec is shown. The minimum sun-earth-probe angle during the solar encounter as a function of the earth-node angle and the orbital inclination is also shown. If the inclination is 60 degrees or more, the minimum SEP angle is not greatly different from the 90 degree value.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 521-534
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  • 28
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    Transmission media effects on precise Doppler tracking (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The effects of the transmission media - the earth's troposphere and ionosphere, and the solar wind - on precise Doppler tracking are discussed. The charged particle effects can be largely removed by dual frequency observations; however there are limitations to these corrections (besides system noise and/or finite integration times) including the effects of magnetic fields, diffraction, and differential refraction, all of which must be carefully evaluated. The earth's troposphere can contribute an error of delta f/f approximately 10 to the minus 14th power.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 450-456
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  • 29
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    Scintillation observations near the sun (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Results on the electron density spectrum, the random velocity and the mean velocity of the solar wind in the region from 5 to 100 solar radii are presented. Results are based on intensity scintillations of incoherent radio sources at different locations and different radio frequencies. The shape of the electron density irregularity spectrum is shown to be well modeled by a power law in wavenumber with a slope that abruptly steepens at higher wavenumbers. This two slope power law model is shown to have a break (defined as the wavenumber of the change of slope) that increases with decreasing distance from the Sun. The fractional random velocity is shown to be insignificant at distances of greater than 40 solar radii, but shows a steady increase with decreasing solar distance inside of 40 solar radii.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 388-396
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  • 30
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    Plasma density mapping in the solar wind through use of VHF radio to measure electron content (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: How the electron content between the Solar probe and the earth can be observed with a minimum of equipment and give a quantitative rationale for the use of a signal near 400 MHz to supplement the telecommunications signal is described. The emphasis is on the method of making content observations and on their value. While far from the Sun, the electron content is so low that the S-X dual-frequency system is insufficiently sensitive and a UHF system is optimum. As the probe approaches the Sun, the UHF may be disrupted by scintillation and the variations of the telecommunications signal must be used for the content measurement. By operating the suggested system in different modes as the solar distance changes, operation during the entire mission is possible.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 397-407
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  • 31
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    A timed-correlated four-link Doppler Tracking system (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Phase perturbations that occur in the following components of the one and two-way systems are considered: (1) one-way system (signal from A to B): station a oscillator - transmitter A antenna A - signal path - antenna B - receiver B station B oscillator - recording system B; (2) two-way system (signal from A to B back to A): station A oscillator - transmitter A - antenna A - signal path up - antenna B - transponder B - antenna B - signal path down - receiver A - station A oscillator - recording system A. A symmetrical one- and two-way system which can identify the place of origin of the fluctuation and quantify it so as to recover the unperturbed phase at a given moment of time by time-correlating the phase fluctuations obtained in the one- and two-way data taken at both stations is described
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 457-497
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    Gravitational wave detection with the solar probe: I. Motivation (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Questions are posed and answered through discussion of gravitational wave detection with the Solar Probe. Discussed are: (1) what a gravitational wave is; (2) why wave detection is important; (3) what astrophysical information might be learned from these waves; (4) status of attempts to detect these waves; (5) why the Solar Probe is a special mission for detecting these waves; (6) how the Solar Probe's expected sensitivity compares with the strength of predicted gravitational waves; and (7) what gravity wave searchers will do after the Solar Probe.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 433-440
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  • 33
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    Magnetohydrodynamic simulation of coronal mass ejections into the solar wind (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A state of the art fluid continuum technique to describe the MHD transient respose of the corona below 10 solar radii during two well observed events (flares on 21 August 1973 and 5 September 1973) is reviewed. It is concluded that the computer simulation should be subjected to in situ verification of as many of its initial assumptions as possible. Its ability to provide a rational basis for physical understanding of mass ejections suggests its use as one of the tools used in the planning and analysis of such encounter missions.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 367-387
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  • 34
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    Spectroscopic mapping of solar wind velocities (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: During the total solar eclipse of 1970, measurements of resonantly scattered Lyman-alpha radiation from the solar corona revealed a means to determine temperatures and densities in the solar corona beyond 1.5 R solar radii. A natural extension of this work is to use the Solar Probe to measure the spectral line profile of Lyman-alpha radiation backscattered toward the Sun from coronal regions between 4 R solar radii and 10 R solar radii. The backscattered profile would provide unique and quantitative determinations of the outlaw velocities of coronal material into the solar wind. Such information is of critical importance for understanding solar-wind formation and solar-terrestrial effects on the earth's climate. There is no known way to obtain this information without a Solar Probe-type mission.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 354-365
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  • 35
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    Solar wind science for a solar probe mission (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Scientific objectives for solar-wind investigations relevant to a Solar Probe mission are outlined and put in perspective. Information gained from the various possible measurements are also listed.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 273-280
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  • 36
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    Solar neutron spectroscopy near the sun (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A brief note is summarized to show the importance of solar neutron observations for the advancement of phenomena crucial for solar physics, and to suggest the constraints which must be placed on the Solar Probe Mission for carrying out studies of this kind.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 243-261
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  • 37
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    Low-energy protons: Gradients in interplanetary space and distribution in the solar corona (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: First and second order anisotropy measurements are proposed as a tool for studying the coronal source function and interplanetary propagation of low energy protons. Optimum orbit and attitude requirements are suggested for a three telescope system. Some limitations with regard to the lower energy limit for a feasible set-up are discussed.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 234-239
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  • 38
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    Magnetic field measurements from the solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: An optical system for the solar probe is described as well as its capability for improvements in spatial resolution. A magnetograph for measuring the elementary flux tube and obtaining vector geometry field geometry offers the possibility of looking for low contrast weak structure. With the probe's orbit passing over the pole, the structure of the polar field can be directly measured. The detector plane of the system receives a telecentric image of the objective. Because there is an aperture in this focal plane that can both move and change size, polarized line profiles can be obtained at arbitrary points with variable spatial resolution. The telescope microprocessor searches for the magnetic elements and then constructs the vector field.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 155-158
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  • 39
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    New perspectives for solar observations (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The merits and demerits of an approach to the Sun (more closely than about one AU) are examined. High resolution imaging (approximately 0.1 arc sec) to be obtained with the shuttle-borne solar optical telescope, will permit conclusive observations relating to the structure of the quiet solar atmosphere, sunspots, spicules, oscillations, and many other problems of solar astrophysics. Beyond this limit important unresolved structure will exist, especially in optically thin regions or in regions with strong magnetic fields. Ambiguity will remain in solar imagery because a single line of sight cannot suffice completely to untangle the vertical dimension from the two horizontal dimensions. A solar probe with a complement of solar telescopes would provide two lines of sight for solar viewing and increase knowledge of the three dimensional structure of the solar atmosphere.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 81-88
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  • 40
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    Gravitational experiments on solar probe (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A covariance analysis was performed for a solar probe trajectory which encounters the sun at four solar radii. The unknown parameters in the analysis are the six initial cartesian coordinates for the probe, six initial cartesian coordinates for the earth, the astronomical unit, the solar gravitational quadrupole coefficient and two post Newtonian meters (beta, gamma). Errors in the unknown parameters were computed as a function of standard errors on the radio tracking data and on the nongravitational forces which act on the probe. Results were obtained for several tracking geometries and for several orbital inclinations to the ecliptic. The analysis shows that the principal scientific result from the radio tracking of a solar probe would be the determination of the quadrupole moment, which would place a constraint on models of the solar interior.
    Keywords: SOLAR PHYSICS
    Type: A Close-up of the Sun; p 42-57
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  • 41
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    Ground tracking system phase fluctuation spectra (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Spectral analysis of solar wind plasma fluctuation requires knowledge of the average ground tracking system phase fluctuation spectrum. Typical ground tracking system phase fluctuation spectra are presented as deduced from two-way S-band Doppler noise measured at large Sun-Earth-Probe angles.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 125-128
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  • 42
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    A solar wind turbulence event during the Voyager 1978 solar conjunction profiled via new DSN radio science (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: A radio science data capability within the DSN Tracking System is described. This capability consists of routine provision of phase fluctuation data concurrently computed over several different time scales. This capability was used to observe phase fluctuation spectral characteristics during a rapid increase in solar wind turbulence that occurred during a July 23, 1978 track of the Voyager 1 spacecraft by Deep Space Station 11. It is suggested that the capability will prove useful in studies of variations of solar wind phase fluctuation spectral characteristics with, for instance, parameters such as the solar cycle and radial distance.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 55-58
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  • 43
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    A hard X-ray and gamma ray observation of the 22 November 1977 solar flare (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The Franco-Soviet experiment package Signe 2 MP for solar and cosmic X and gamma ray observations, launched aboard a Soviet Prognoz satellite into a highly eccentric earth orbit is described. An uncollimated NaI detector 37 mm thick by 90 mm diameter, placed on the upper surface of the satellite faced the sun. A collimated lateral NaI detector 14 mm thick by 38 mm diameter also faced the sun, and a similar lateral detector faced the anti-solar direction. Data tapes reveal an intense solar flare up to energies of up to 5 MeV, with evidence for line emission at 2.23 MeV and possibly 4.4 MeV. The event observed was associated with the Mc Math Plage Region 15031, and an H-alpha flare of importance 2B. It is not yet clear what radio emission is associated with the X-ray observation.
    Keywords: SOLAR PHYSICS
    Type: NASA. Goddard Space Flight Center Gamma Ray Spectry. in Astrophys.; p 70-75
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  • 44
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    Measurements of extreme-ultraviolet emission-line profiles near the solar limb (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Line profiles of optically thin extreme-ultraviolet emission lines observed in a quiet sun region at positions within and above the white-light limb with the NRL slit spectrograph (S082-B) on Skylab are discussed. Absolute line intensities and full widths at half-maximum are presented for lines formed over the temperature range from about 10,000 to 22,000 K. The line intensities are compared with the predictions of simple atmospheric models consisting of a spicule component and a thin spherically symmetric or network models, but can be explained by assuming that the emission arises from spicule-like inhomogeneities. Random mass-motion velocities are calculated. The velocity increases with increasing temperature of line formation. Near the limb and above about 4000 K the calculated velocity is consistent with the predictions of a constant acoustic flux passing through the transition zone. For the ions formed at temperatures not less than about 63,000 K, the velocity is found to increase with increasing height above the white-light limb.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 226
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  • 45
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    Resonant absorption of Alfvenic surface waves and the heating of solar coronal loops (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A first-order mass- and energy-balance model is developed for steady-state EUV 'coronal rain' loops that are not associated with postflare events and are often seen over sunspot umbrae. The model disregards variations in a loop's thermodynamic and magnetic properties along magnetic-field lines and yields average properties of the resonant absorption sheath, the boundary layer, and the loop's interior. Both irreversible heating by Alfvenic surface waves and energy transport via induced boundary-layer convection are taken into account in the analysis. Results that include predictions of the temperatures of the sheath and the boundary-layer plasma, the temperature of the interior plasma, the radiative output of the loop, and the filling factor associated with this radiation are given in terms of the period and velocity amplitude of the relevant surface wave as well as various parameters that characterize a typical 'coronal rain' loop. These results are shown to be consistent with the observed minimum and maximum temperatures as well as the radiative output of typical 'coronal rain' loops.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 226
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  • 46
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    EUV spectra from Skylab /1175-1940 A/ - Mass motions in the transition zone in regions of solar activity (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The profiles of spectral lines in the 1100-2000-A range emitted by transition-zone ions in regions of solar activity are discussed. The data were recorded by the NRL spectrograph on Skylab. At the spatial resolution of the Skylab spectrograph (2 x 60 arcsec), it is shown that the line profiles result from the superposed emission of a number of physically distinct regions at different electron densities and with different mass motions. Although high densities are found for some surgelike phenomena at transition-zone temperatures, the densities can also be comparable to normal active-region densities. Line profiles, as well as spectral line intensities, must be considered if meaningful theoretical models of dynamic activity in the transition zone are to be constructed.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 69; 1, Se; Sept
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  • 47
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    The composition of corotating energetic particle streams (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The relative abundances of 1.5-23 MeV per nucleon ions in corotating nucleon streams are compared with ion abundances in particle events associated with solar flares and with solar and solar wind abundances. He/O and C/O ratios are found to be a factor of the order 2-3 greater in corotating streams than in flare-associated events. The distribution of H/He ratios in corotating streams is found to be much narrower and of lower average value than in flare-associated events. H/He in corotating energetic particle streams compares favorably in both lack of variability and numerical value with H/He in high-speed solar wind plasma streams. The lack of variability suggests that the source population for the corotating energetic particles is the solar wind, a suggestion consistent with acceleration of the corotating particles in interplanetary space.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 224
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  • 48
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    Impulsive solar X-ray bursts (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A set of 22 simple impulsive solar flares, identified in the OSO 5 hard X-ray data, has been analyzed together with coincident microwave and meter-wave radio observations. The rise times and fall times of the X-ray bursts are found to be highly correlated and effectively equal, strongly suggesting a flare-energizing mechanism that is reversible. The good time resolution available for these observations reveals that the microwave emission is influenced by an additional process, evident in the tendency of the microwave emission to peak later and decay more slowly than the symmetric X-ray bursts. Meter-wave emission is observed in coincidence with five events which also show strong time correlation between the X-ray and microwave burst structure. This meter-wave emission is characterized by U-burst radiation, indicating confinement of the flare source. The relationship found between the X-ray burst duration and the calculated flare diameter, together with the thermal character of the X-ray spectra, gives additional support to the hypothesis that the impulsive component is driven by adiabatic compression and expansion of a magnetically confined plasma which is the common primary source of both X-ray and microwave emission.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 223
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  • 49
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    Densities in the quiet sun and polar coronal holes from EUV line ratios involving O III /1666.15 A/ (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 226
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  • 50
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    Sources of magnetic fields in recurrent interplanetary streams (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The paper examines sources of magnetic fields in recurrent streams observed by the Imp 8 and Heos spacecraft at 1 AU and by Mariner 10 en route to Mercury between October 31, 1973 and February 9, 1974, during Carrington rotations 1607-1610. Although most fields and plasmas at 1 AU were related to coronal holes and the magnetic field lines were open in those holes, some of the magnetic fields and plasmas at 1 AU were related to open field line regions on the sun which were not associated with known coronal holes, indicating that open field lines may be more basic than coronal holes as sources of the solar wind. Magnetic field intensities in five equatorial coronal holes, certain photospheric magnetic fields, and the coronal footprints of the sector boundaries on the source surface are characterized.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; Sept. 1
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  • 51
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    Limb-brightening observations from the OSO-7 satellite. III - Comparison of EUV line intensities of Fe XII, Fe XI, Fe XV, Si X and S XII, Si IX and S XI with predictions (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Continuing a study of heliocentric dependence of EUV emission line intensities observed by the Goddard OSO-7 spectroheliograph in 1972, the variation of lines of the ions Fe XII, Fe XI, Fe XV, Si X and S XII, Si IX and S XI is compared with the results of individual calculations for these ions, including theoretical intensities presented for Fe XII and Fe XI. Agreement is found to be good for Fe XII and reasonable for some of the lines of the other ions which in general are weaker in intensity. Several apparent anomalies are found however which may be due to unknown line components near the wavelengths observed.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 67; 1, Ju; June 197
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  • 52
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    An instability of finite amplitude circularly polarized Alfven waves (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A demonstration is presented that a finite-amplitude circularly-polarized Alfven wave is generally unstable in a MHD fluid. The wave decays by a four-wave coupling process in which the daughter waves are forward propagating random density and magnetic fluctuations and a backward-propagating magnetic wave. For parameters typical of the solar corona and the solar wind (thermal to magnetic energy density ratios between 0.1 and 1, and values between 0.1 and 0.9 for the ratio of magnetic energy density of the initial Alfven wave to that of the background magnetic field), large decay rates are found.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 219
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  • 53
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    Electron densities in solar flare and active region plasmas from a density-sensitive line ratio of Fe IX (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 219
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  • 54
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    Direct observation of the latitudinal extent of a high-speed stream in the solar wind (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The latitudinal boundaries of stationary fast solar wind streams emerging from equatorward extensions of the sun's polar coronal holes are studied. Simultaneous data from the Helios 1 and Imp spacecraft at different heliographic latitudes are compared. The measured latitudinal speed gradient of 30 km/s/deg shows that large angular speed gradients occur at the leading edges of fast streams and also with respect to latitude. The data indicate that longitudinal speed gradients are steeper near 0.3 AU than at 1.0 AU. Generally, regions with large angular speed gradients are observed to separate fast streams from the surrounding slower plasma. This suggests the existence of mechanisms which diminish longitudinal speed gradients as the plasma travels toward 1.0 AU. It also seems that the distribution of solar wind speeds on a near-sun spherical surface has large mesalike high-speed regions. Comparisons of Helios 1 and Imp data with corona observations supports the hypothesis that high-speed solar wind streams emerge from coronal holes.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; Mar. 1
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  • 55
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    Solar wind stream interfaces (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Results are presented for a superposed epoch analysis of discontinuous solar wind interfaces. The average time-space profiles of stream interfaces are discussed with reference to fluid properties (flow speed, pressure ridge, density, electron and proton temperatures) and kinetic properties (electron core and halo, flow speed fluctuations, electron heat flux, alpha particles). Other aspects of stream interfaces are described, such as the persistence of individual interfaces, shock associations, the sector boundaries of the interplanetary magnetic field, and sudden impulses in the geomagnetic field. Interface position is considered in terms of the observed temperature jump. A conceptual model of high-speed stream evolution is proposed.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; Apr. 1
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  • 56
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    The electron density at 10 to the 5th K in different regions of the solar atmosphere derived from an intersystem line of O IV (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 65; 2, Ap; Apr. 197
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  • 57
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    A phenomenological model of solar flares (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The energy of solar flares is derived from the magnetic energy of fields convected to the sun's surface and subsequently converted to heat and energetic particles within the chromosphere. The circumstances of this conversion in most current models is magnetic flux annihilation at a neutral sheet. An analysis is conducted of the constraints of flux annihilation. It is shown that the present evidence of solar cosmic rays, X-rays, gamma-rays, and total energy suggests a choice of annihilation not at a neutral point, but by an enhanced dissipation of a field-aligned current. The field configuration is related both to its origin and to the extensive theory and laboratory experiments concerned with this configuration in magnetic fusion. The magnetic field model is applied to the August 4 flare. It is shown how the plasma heating in the annihilation region balanced by thermal conduction leads to a plasma temperature of about 20 million deg K.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 221
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  • 58
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    Spectrum of mean free paths near earth in the solar cosmic ray event of April 29, 1973 (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; June 1
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  • 59
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    Long-term variations of selected solar wind properties - IMP 6, 7, and 8 results (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Studies of the variability of the solar wind are extended to include the minimum of solar cycle 20; attention is given to the He abundance, the relative He-H velocity difference, the He-H temperature ratio, the solar coronal proton density, speed, rms velocity variation, temperature and number flux, and the kinetic and total energy fluxes. The solar wind data are from observations conducted by the IMP-6, -7 and -8 satellites. A well-developed corotating stream structure appearing in January 1973 and disappearing in mid-1976 receives particular consideration. An increase in proton number and total energy fluxes after September 1972 may be due to areal expansion of both polar coronal holes, and may be associated with compression of the low-speed equatorial disk-shaped region postulated to surround the sun in interplanetary space.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; May 1
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  • 60
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    The importance of spectroscopy in the 80-800 A region for plasma diagnostics in the solar atmosphere (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The importance of the spectral range from about 80 to 800 A for determining physical conditions in different regions of the solar atmosphere is discussed. Examples are given of line ratios that may be used to determine electron densities in quiet-sun regions, active regions, and flares. The possibility of determining electron temperatures from line ratios in the EUV is considered. It is shown that profiles, as well as intensities, of spectral lines must be obtained for a proper interpretation of the spectra. Approximate parameters are provided for a solar grazing-incidence spectrograph suitable for the study of the 80-800-A wavelength region.
    Keywords: SOLAR PHYSICS
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  • 61
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    Low frequency spectra of type III solar radio bursts (1978)
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    Publication Date: 2011-08-17
    Description: Flux density spectra have been determined for 91 simple type III solar bursts observed by the Goddard Space Flight Center radio astronomy experiment on the IMP-6 spacecraft during 1971 and 1972. Spectral peaks were found to occur at frequencies ranging from 44 kHz up to 2500 kHz. Half of the bursts peaked between 250 kHz and 900 kHz, corresponding to emission at solar distances of about 0.3 to 0.1 AU. Maximum burst flux density sometimes exceeds 10 to the -14th W/sq m/Hz. The primary factor controlling the spectral peak frequency of these bursts appears to be a variation in intrinsic power radiated by the source as the exciter moves outward from the sun, rather than radio propagation effects between the source and IMP-6. Thus, a burst spectrum strongly reflects the evolution of the properties of the exciting electron beam, and according to current theory, beam deceleration could help account for the observations.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 59; Oct. 197
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  • 62
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    Measurement of the profile and intensity of the solar He I lambda 584-A resonance line (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The intensity and profile of the helium resonance line at 584 A from the entire disk of the sun was investigated by using a rocket-borne helium-filled spectrometer and a curve-of-growth technique. The line profile was found to be accurately represented by a Gaussian profile with full width at half maximum of 122 + or - 10 mA, while the integrated intensity was measured to be 2.6 + or - 1.3 billion photons/s per sq cm at solar activity levels of F(10.7) = 90.8 x 10 to the -22nd per sq m/Hz and Rz = 27. The measured line width is in good agreement with previous spectrographic measurements, but the integrated intensity is larger than most previous photoelectric measurements. However, the derived line center flux of 20 + or - 10 billion photons/s per sq cm/A is in good agreement with values inferred from airglow measurements.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; Dec. 1
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  • 63
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    A three-dimensional model of corotating streams in the solar wind. I - Theoretical foundations (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The paper is concerned with the development of the theoretical and mathematical background pertinent to the study of steady, corotating solar wind structure in all three spatial dimensions. The dynamical evolution of the plasma in interplanetary space (defined as the region beyond roughly 35 Rs where the flow is supersonic) is approximately described by the nonlinear, single-fluid, polytropic magnetohydrodynamic or hydrodynamic equations. Efficient numerical techniques are outlined for solving this complex system of coupled, hyperbolic partial differential equations. The present formulation is inviscid and nonmagnetic, but the methods used allow for the potential inclusion of both features with only modest modifications. A simple, highly idealized hydrodynamic model stream is examined to illustrate the fundamental processes involved in the three-dimensional dynamics of stream evolution. It is found that spatial variations in the rotational stream interaction mechanism produce small nonradial flows on a global scale that lead to the transport of mass, energy, and momentum away from regions of relative compression and into regions of relative rarefaction. Comparison with simpler models demonstrates the essential nonlinear, multidimensional nature of the interplanetary dynamics.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; Dec. 1
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  • 64
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    The radial variation of corotating energetic particle streams in the inner and outer solar system (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Spacecraft observations of 0.9 to 2.2 MeV protons are used to evaluate the radial gradient of long-lived corotating energetic particle streams for several time periods from mid-1973 to mid-1976. New evidence is presented for a positive gradient between 0.3 and some 3-4 AU and a negative one beyond some 3-5 AU. The relation between the corotating events in the inner solar system and the accompanying interplanetary magnetic field and solar wind is examined. It is shown, independently of possible secondary latitudinal effects, that between 0.3 and 1 AU, in a region where gradients up to 300%/AU exist, the particle stream is propagating inside a fast solar wind stream in a region adjacent to low- and high-speed stream interactions.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; Oct. 1
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  • 65
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    The radial gradients and collisional properties of solar wind electrons (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The plasma electron detector on Mariner 10 is used to obtain measurements of electron density and temperature in the interplanetary medium between heliocentric distances of 0.85 and 0.45 AU. The observations show quantitatively that the core of the electron distribution function can be described as collisional at least for radial distances within 1 AU, since with a very few well-marked exceptions associated with high-speed streams, the Coulomb collisional momentum relaxation length is less than the density scale height at all times and all radial distances at which data were obtained. It is found that the Coulomb energy exchange collisions between the core and the (test) halo population are negligible. The power law exponent of the core temperature is about -0.3, whereas the halo temperature is almost independent of heliocentric distance.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; Aug. 1
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  • 66
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    The spiral field inhibition of thermal conduction in two-fluid solar wind models (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The paper reports on two-field models which include the inhibition of thermal conduction by the spiraling interplanetary field to determine whether any of the major conclusions obtained by Nerney and Barnes (1977) needs to be modified. Comparisons with straight field line models reveal that for most base conditions, the primary effect of the inhibition of thermal conduction is the bottling-up of heat in the electrons as well as the quite different temperature profiles at a large heliocentric radius. The spiral field solutions show that coronal hole boundary conditions do not correspond to states of high-speed streams as observed at 1 AU. The two-fluid models suggest that the spiral field inhibition of thermal conduction in the equatorial plane will generate higher gas pressures in comparison with flows along the solar rotation axis (between 1 and 10 AU). In particular, massive outflows of stellar winds, such as outflow from T Tauri stars, cannot be driven by thermal conduction. The conclusions of Nerney and Barnes remain essentially unchanged.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; Aug. 1
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  • 67
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    Theoretical intensity ratios for the UV lines of Mg VII, Si IX and S XI (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Energy levels, oscillator strengths, and electron collision strengths have been computed for the configurations 2s2 2p2, 2s 2p3, 2p4 of Mg VII, Si IX, and S XI. Level populations for the ground configuration and theoretical intensity ratios for the UV lines are tabulated for electron densities and temperatures appropriate to the solar atmosphere. The identification of the Mg VII, Si IX, and S XI UV lines is discussed.
    Keywords: SOLAR PHYSICS
    Type: Royal Astronomical Society; vol. 184
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  • 68
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    XUV spectra of the 1973 June 15 solar flare observed from Skylab. III - A list of spectral lines from 1000 to 1940 A (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A wavelength list of spectral lines between 1000 and 1940 A is presented for the solar flare that occurred on June 15, 1973. The spectra were recorded by the NRL spectrograph on Skylab. The spectral resolution is 0.06 A. Intensities, identifications, and estimates of line widths are given. The intensity of the continuum is also given at 50-A intervals between 1400 and 1900 A. The wavelength list includes about 1400 lines; about 30% of these lines are not indentified. Because of the high wavelength resolution, this line list will be useful as a source of identification for some stellar as well as solar spectra. In particular, the list should be a useful aid in the identification of lines in the spectra of stars with classifications close to that of the sun. Spectra of such stars may be obtained from the recently launched IUE spacecraft. It is also interesting to compare the list with some of the spectra of early-type stars recorded by Copernicus.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal Supplement Series; 37; July 197
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  • 69
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    Comparisons of measured and calculated potential magnetic fields (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Photospheric line-of-sight and transverse-magnetic-field data obtained, with a vector magnetograph system for an isolated sunspot are described. A study of the linear polarization patterns and of the calculated transverse field lines indicates that the magnetic field of the region is very nearly potential. The H-alpha fibril structures of this region as seen in high-resolution photographs corroborate this conclusion. Consequently, a potential-field calculation is described using the measured line-of-sight fields together with assumed Neumann boundary conditions; both are necessary and sufficient for a unique solution. The computed transverse fields are then compared with the measured transverse fields to verify the potential-field model and assumed boundary values. The implications of these comparisons for the validity of magnetic-field extrapolations using potential theory are discussed.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 57; Apr. 197
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  • 70
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    Electron densities in the solar corona from density-sensitive line ratios in the N I isoelectronic sequence (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 226
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  • 71
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    Magnetic field in the primitive solar nebula (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Carbonaceous chondrites have apparently been magnetized in their early history in magnetic fields with intensities of 0.1 to 10 G, but the origin of the magnetizing field has remained obscured. It is suggested that the magnetic field recorded in the remanence of carbonaceous chondrites may have been produced by a self-excited hydromagnetic dynamo in the gaseous preplanetary nebula from which the solar system is thought to have formed. Recently computed models for the evolution of the preplanetary nebula, consisting of turbulent and differentially rotating gaseous disks with characteristic radial scales of several AU, are used to demonstrate the feasibility of this hypothesis. The maximum field intensity that might be realized by the dynamo production process is estimated to be as high as 1 to 10 G, taking into account two dynamical mechanisms that limit the strength of the field (the Coriolis force and ambipolar diffusion).
    Keywords: SOLAR PHYSICS
    Type: Nature; 276; Nov. 30
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  • 72
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    Electron heating within interaction zones of simple high-speed solar wind streams (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: In the present paper, electron heating within the high-speed portions of three simple stream-stream interaction zones is studied to further our understanding of the physics of heat flux regulation in interplanetary space. To this end, the thermal signals present in the compressions at the leading edges of the simple high-speed streams are analyzed, showing that the data are inconsistent with the Spitzer conductivity. Instead, a polynomial law is found to apply. Its implication concerning the mechanism of interplanetary heat conduction is discussed, and the results of applying this conductivity law to high-speed flows inside of 1 AU are studied. A self-consistent model of the radial evolution of electrons in the high-speed solar wind is proposed.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; Nov. 1
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  • 73
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    Characteristic electron variations across simple high-speed solar wind streams (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The paper deals with electron variations across simple high-speed streams. Comprehensive scans of the shapes of electron distributions measured at the highest bulk speeds confirm the results of Rosenbauer et al. (1976, 1977) and show that the electron velocity distributions can be broken down into a low-energy or core component and a high-energy strongly beamed component. The low-energy component displays many characteristics expected from a fluid: the internal particle coupling necessary to maintain this state must result from both binary Coulomb collisions and wave-particle interactions. The high-energy or halo component displays many characteristics expected to develop in the absence of collisions beyond a certain base radius. These electrons appear to evolve under the primary influence of static interplanetary magnetic and electric fields and, therefore, develop very anisotropic velocity distributions.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; Nov. 1
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  • 74
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    Magnetic fields and flows between 1 and 0.3 AU during the primary mission of Helios 1 (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Magnetic phenomena and coronal holes observed by Helios 1 during nearly four rotations of the sun are discussed. It is estimated that the magnetic field intensity of open field lines in some of the coronal holes (which changed in shape and latitude from one rotation to the next) was of the order of 10-20 G during the studied period, December 1974 to March 1975. Magnetic field polarity, cold magnetic enhancements, and longitudinal widths of the stream are described. It is concluded that between the sun and 0.3 AU there was a diverging stream surrounded by a thin boundary layer in which there was large velocity shear. There is evidence for compression of the magnetic field in the western boundary layer.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 83; Nov. 1
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  • 75
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    Measurements of solar UV flux in the stratosphere (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Solar UV flux measurements were obtained on STRATCOM-VIII from liftoff to sunset. Spectra cover the wavelength range from 1979A to 2879A and altitudes from about 25-42 km over a wide range of solar zenith angles. Good agreement is obtained between the observed spectra and synthetic spectra calculated using a two stream radiative transfer model.
    Keywords: SOLAR PHYSICS
    Type: STRATCOM 8 Data Workshop and Suppl.; p 64-67
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  • 76
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    Measurements of ultraviolet fluxes (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An UV spectrometer on STRATCOM 8 measured the UV scattered light in the 2000 A to 3000 A range. These data were obtained at a variety of viewing angles. In addition data in 3000 A to 4000 A range were obtained using four photometers with filters approximately 300 A wide. This instrument was downward viewing in order to obtain information on the variability of the albedo in this wavelength range. Another four channel instrument, looking upward, was designed to measure ozone overburden.
    Keywords: SOLAR PHYSICS
    Type: NASA. Goddard Space Flight Center STRATCOM 8 Data Workshop and Suppl.; p 63
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  • 77
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    Measurement of 200-400 nm solar UV fluxes on the STRATCOM 8A balloon flight (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A filter wheel UV Spectroirradiometer was used to measure solar UV fluxes in 10 bandpasses in the 200-400 nm region at altitudes up to 40 km on Stratcom 8A. Ozone layer thicknesses were derived from the balloon ascent measurements and an ozone density profile obtained. Measurements at the 39-40 km float altitude before and after local noon give a solar flux in the (220 + or - 5) nm O2-O3 transmission window of 4.53 x .000001 W/(cm squared-nm) at approximately 1 A U on 29 September 1977, when the sunspot number was about 63.
    Keywords: SOLAR PHYSICS
    Type: NASA. Goddard Space Flight Center STRATCOM 8 Data Workshop and Suppl.; p 56-62
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  • 78
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    Solar plages and the vorticity of the earth's atmosphere (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Three superimposed epoch analyses of the vorticity area index (VAI) at 500 mbar are described. The analyses used the following definitions of the zero days: (1) the central meridian passage (CMP) of very active solar plages; (2) the occurrence of peak values of the 10.7 cm solar radio flux; and (3) the CMP of active solar plages also accompanied at CMP by sharp rises in 10.7 cm solar radio noise. All three superimposed epoch analyses show a sustained rise in VAI several days before the zero day; the rise continues through the zero day and is followed by a sustained minimum in VAI several days after the zero day. The results suggest that the location of the very active plages play an important role in determining their meteorological influence. It is possible that the initial rise in VAI is caused by enhanced electromagnetic radiation associated with the solar activity, and that the decrease some days later is the result of the geomagnetic storm particle emission that generally follows the zero date.
    Keywords: SOLAR PHYSICS
    Type: Nature; 274; July 13
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  • 79
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    The prediction of fast stream front arrivals at the earth on the basis of solar wind measurements at smaller solar distances (1978)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: The problems involved in the prediction of the arrival of fast solar wind streams at the earth on the basis of measurements made by space probes in the region between 0.3 and 1 AU are discussed. It is shown that arrival time predictions accurate to within a few hours that can be made at least as long as the large scale conditions on the Sun are relatively stationary as observed near the time of solar minimum. However, the latitudinal extent of the respective high speed streams is found to be important for making quantitative predictions. Coronal data sufficient for locating the sources of high speed streams can improve the precision of these predictions.
    Keywords: SOLAR PHYSICS
    Type: AGARD Operational Modelling of the Aerospace Propagation Environ., Vol. 1 and 2; 5 p
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  • 80
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    Solar Terrestrial programs: A five year plan (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Major projects to be initiated in the 1980-1985 period, designed to study the Sun, the heliosphere, Earth's magnetosphere, and the upper atmosphere involve the use of spacelab as well as free flying spacecraft. Current and recent investigations in these areas are reviewed and the guiding principles followed in planning future missions are examined. The implementation strategy, the planning process, and supporting research and technology are discussed.
    Keywords: SOLAR PHYSICS
    Type: NASA-TM-82351
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  • 81
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    Radio evidence on the particle distribution functions in the corona following flares (1978)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: This paper summarizes results of radio studies of the distribution functions (number, energy distribution, and pitch-angle distribution) of the energetic particles that are produced at the time of solar flares. The clues and constraints they impose on the mechanisms of acceleration are considered, bearing in mind that radio evidence implies that there are at least two stages of acceleration in many flares. The distribution functions of the particles resulting from first-phase acceleration, first- and/or second-phase, and second-phase acceleration are discussed.
    Keywords: SOLAR PHYSICS
    Type: Astronomical Society of Australia; vol. 3
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  • 82
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    Coronal propagation and storage at energies approximately 1 MeV/nucleon (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Energetic particle events relating to quasi-stationary particle populations, solar flare events, and solar composition are discussed in the context of similar observations likely to be made during solar probe encounter. Particlar emphasis is given to interrelationships with coronal magnetic structure and plasma processes. General instrumental requirements are listed, and it is concluded that energetic particle detectors meeting these requirements will successfully complement other essential experiments on the Solar Probe.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 219-233
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  • 83
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    Solar probe studies of the solar convection zone (1978)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: From a distance of 3 solar radii as may be attainable with a solar probe, a resolution of 5 arc second such as would be possible from a small telescope will allow observations of solar features as small as 50 km. Because the solar probe will be as close to the sun as 0.014.AU, the effective resolution is increased a factor of 70. A 3 inch telescope on the solar probe will have resolution equivalent to a 200 inch telescope on earth. Thus observations could be carried into the size scale which presumably is responsible for the turbulent viscosity. The preferred instrument for studying the dynamics of the solar convection zone is a magnetograph operated in a Doppler mode. A Fabrey-Perot etalon can provide the spectral discrimination necessary for the measurement of velocities. The instrument can provide long time base observations of the solar p-mode oscillations and permit determination of the rate of solar rotation at a depth 25% below the solar surface to an accuracy of better than 0.5 km/s.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 92-93
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  • 84
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    Electron studies of acceleration processes in the corona (1978)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The solar probe mission can obtain unique and crucially important measurements of electron acceleration, storage, and propagation processes in the corona and can probe the magnetic field structure of the corona below the spacecraft. The various energetic electron phenomena which will be sampled by the Solar Probe are described and some new techniques to probe coronal structures are suggested.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 191-204
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  • 85
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    A theory of local and global processes which affect solar wind electrons. 1: The origin of typical 1 AU velocity distribution functions: Steady state theory (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A detailed first principle kinetic theory for electrons which is neither a classical fluid treatment nor an exospheric calculation is presented. This theory illustrates the global and local properties of the solar wind expansion that shape the observed features of the electron distribution function, such as its bifurcation, its skewness and the differential temperatures of the thermal and suprathermal subpopulations. Coulomb collisions are substantial mediators of the interplanetary electron velocity distribution function and they place a zone for a bifurcation of the electron distribution function deep in the corona. The local cause and effect precept which permeates the physics of denser media is modified for electrons in the solar wind. The local form of transport laws and equations of state which apply to collision dominated plasmas are replaced with global relations that explicitly depend on the relative position of the observer to the boundaries of the system.
    Keywords: SOLAR PHYSICS
    Type: NASA-TM-79621
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  • 86
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    Stochastic acceleration of solar flare protons (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The acceleration of solar flare protons is considered by cyclotron damping of intense Alfven wave turbulence in a magnetic trap. The energy diffusion coefficient is computed for a near-isotropic distribution of super-Alfvenic protons and a steady-state solution for the particle spectrum is found for both transit-time and diffusive losses out of the ends of the trap. The acceleration time to a characteristic energy approximately 20 Mev/nucl can be as short as 10 sec. On the basis of phenomenological arguments an omega/2 frequency dependence for the Alfven wave spectrum is inferred. The correlation time of the turbulence lies in the range .0005 less than tau/corr less than .05s.
    Keywords: SOLAR PHYSICS
    Type: SU-SUIPR-739
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  • 87
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    Nonlinear stability of solar type 3 radio bursts. 1: Theory (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A theory of the excitation of solar type 3 bursts is presented. Electrons initially unstable to the linear bump-in-tail instability are shown to rapidly amplify Langmuir waves to energy densities characteristic of strong turbulence. The three-dimensional equations which describe the strong coupling (wave-wave) interactions are derived. For parameters characteristic of the interplanetary medium the equations reduce to one dimension. In this case, the oscillating two stream instability (OTSI) is the dominant nonlinear instability, and is stablized through the production of nonlinear ion density fluctuations that efficiently scatter Langmuir waves out of resonance with the electron beam. An analytical model of the electron distribution function is also developed which is used to estimate the total energy losses suffered by the electron beam as it propagates from the solar corona to 1 A.U. and beyond.
    Keywords: SOLAR PHYSICS
    Type: NASA-TM-78079
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  • 88
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    Studies of acceleration processes in the corona using ion measurements on the solar probe mission (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The energy spectra and composition of particles escaping from the Sun provide essential information on mechanisms responsible for their acceleration, and may also be used to characterize the regions where they are accelerated and confined and through which they propagate. The suprathermal energy range, which extends from solar wind energies (approximately 1 KeV) to about 1 MeV/nucleon, is of special interest to studies of nonthermal acceleration processes because a large fraction of particles is likely to be accelerated into this energy range. Data obtained from near earth observations of particles in the suprathermal energy range are reviewed. The necessary capabilities of an a ion composition experiment in the solar probe mission and the required ion measurements are discussed. A possible configuration of an instrument consisting of an electrostatic deflection system, modest post acceleration, and a time of flight versus energy system is described as well as its possible location on the spacecraft.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 173-190
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  • 89
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    A new use of high resolution magnetograms (1978)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: Ground-based solar magnetograms are frequently in error by as much as twenty percent and contribute to the poor correlation between magnetic changes and solar flares. High resolution measurement of the magnetic field component, which is normal to the photosphere and measured at photospheric height, can be used to construct a magnetic flux partition function F. Therefore, dF/dt is an EMF which drives atmospheric currents in reconnecting solar active regions. With a high quality magnetograph, the solar probe can be used to obtain good estimates of F and dF/dt and thereby the energy stored as induced solar atmospheric currents during quiescent interflare periods. Should a flare occur during a favorable observing period, the present method of analysis should show characteristic signatures in F, DF/dt, and especially, in the stored flux computed from dF/dt.
    Keywords: SOLAR PHYSICS
    Type: JPL A Close-up of the Sun; p 159-169
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  • 90
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    Reverse Current in Solar Flares (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An idealized steady state model of a stream of energetic electrons neutralized by a reverse current in the pre-flare solar plasma was developed. These calculations indicate that, in some cases, a significant fraction of the beam energy may be dissipated by the reverse current. Joule heating by the reverse current is a more effective mechanism for heating the plasma than collisional losses from the energetic electrons because the Ohmic losses are caused by thermal electrons in the reverse current which have much shorter mean free paths than the energetic electrons. The heating due to reverse currents is calculated for two injected energetic electron fluxes. For the smaller injected flux, the temperature of the coronal plasma is raised by about a factor of two. The larger flux causes the reverse current drift velocity to exceed the critical velocity for the onset of ion cyclotron turbulence, producing anomalous resistivity and an order of magnitude increase in the temperature. The heating is so rapid that the lack of ionization equilibrium may produce a soft X-ray and EUV pulse from the corona.
    Keywords: SOLAR PHYSICS
    Type: NASA-TM-79749 , SU-IPR-752
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  • 91
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    Time delay occultation data of the Helios spacecraft for probing the electron density distribution in the solar corona (1978)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: S-band time delay measurements were collected from the spacecraft Helios A and B during three solar occultations in 1975/76 within heliocentric distances of about 3 and 215 earth radius in terms of range, Doppler frequency shift, and electron content. Characteristic features of measurement and data processing are described. Typical data sets are discussed to probe the electron density distribution near the sun (west and east limb as well) including the outer and extended corona. Steady-state and dynamical aspects of the solar corona are presented and compared with earth-bound-K-coronagraph measurements. Using a weighted least squares estimation, parameters of an average coronal electron density profile are derived in a preliminary analysis to yield electron densities at r = 3, 65, 215 earth radius. Transient phenomena are discussed and a velocity of propagation v is nearly equal to 900 km/s is determined for plasma ejecta from a solar flare observed during an extraordinary set of Helios B electron content measurements.
    Keywords: SOLAR PHYSICS
    Type: NASA-CR-156950 , BMFT-FB-W-78-03
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  • 92
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    Pioneer 10 observation of the solar wind proton temperature heliocentric gradient (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Solar wind isotropic proton temperatures as measured out to 12.2 AU heliocentric distance by the Ames plasma analyzer aboard Pioneer 10 are presented as consecutive averages over three Carrington solar rotations and discussed. The weighted least-squares fit of average temperature to heliocentric radial distance, R, yields the power law R sup -.52. These average proton temperatures are not correlated as well with Pioneer 10's heliocentric radial distance (-.85) as are the corresponding average Zurich sunspot numbers R sub z (-.95). Consequently, it is difficult to isolate the spatial gradient in the Pioneer 10 solar wind proton temperatures using that data alone.
    Keywords: SOLAR PHYSICS
    Type: NASA-TM-78515 , A-7579
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  • 93
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    Solar activity during Skylab: Its distribution and relation to coronal holes (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Solar active regions observed during the period of Skylab observations (May 1973-February 1974) were examined for properties that varied systematically with location on the sun, particularly with respect to the location of coronal holes. Approximately 90 percent of the optical and X-ray flare activity occurred in one solar hemisphere (136-315 heliographic degrees longitude). Active regions within 20 heliographic degrees of coronal holes were below average in lifetimes, flare production, and magnetic complexity. Histograms of solar flares as a function of solar longitude were aligned with H alpha synoptic charts on which active region serial numbers and coronal hole boundaries were added.
    Keywords: SOLAR PHYSICS
    Type: NASA-TM-78166
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  • 94
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    Experimental solar radio spectrum analyzer (50-100 MHz) (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Summarized is the work carried out under a NASA Grant covering the period 15 October 1977 to 14 January 1978. The grant provided funds for the acquisition of an experimental radio spectrum analyzer covering the band 50-100 MHz, for use in a program of solar radio observations. Components for the experimental analyzer were duly obtained, and the system was assembled, checked, and put into operation in early February 1978. The analyzer is working in an entirely satisfactory manner and, from the time that it has been put into operation, it has played an important part in the on-going research programs in solar radio astronomy being conducted.
    Keywords: SOLAR PHYSICS
    Type: NASA-CR-156079
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  • 95
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    The role of O-type neutral lines in magnetic merging during substorms and solar flares (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An analytical model of O-type configurations was derived, for visualizing the geometry and for numerical treatment of plasma flows. It was found that at a certain distance from the neutral line the mean particle motion became decoupled from that of magnetic field lines (which obey the MHD condition). The decoupling distance depended on initial conditions in momentum space, suggesting that the MHD approximation which averages out such conditions may not suffice for describing plasma dynamics near the neutral line. It was also found that after inflowing particles are decoupled from the field line motion, they go over to a mode of runaway acceleration along the neutral line. It is concluded that if merging occurs at an X-O pair, two particle populations may be expected - low energy particles accelerated adiabatically by earthward convection past the X-type line and high-energy particles convected towards the O-type line. The second acceleration process depends critically on the rapidity of merging and is therefore expected to vary considerably from event to event.
    Keywords: SOLAR PHYSICS
    Type: NASA-TM-78093
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  • 96
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    Limb darkening 1945-3245 A for the quiet sun from Skylab data (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Limb-darkening measurements of the quiet sun in the spectral range 1945-3245 A have been made using NRL's SO82B instrument on board Skylab. The spectral intensities have been averaged over 10 A wavelength bands, and coefficients for linear, quadratic, and logarithmic fits to the observed center-to-limb variations have been calculated and tabulated as a function of wavelength. The quadratic fits are found to represent the observations best, the observed and calculated values agreeing to better than plus or minus 15% on the average. Attention is drawn to the value of the results for ultraviolet photometry of eclipsing binaries.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 226
    Format: text
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  • 97
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    Radiative transfer of X-rays in the solar corona (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The problem of resonance scattering of X-ray emission lines in the solar corona is investigated. For the resonance lines of some helium-like ions, significant optical depths are reached over distances small compared with the size of typical coronal features. A general integral equation for the transfer of resonance-line radiation under solar coronal conditions is derived. This expression is in a form useful for modeling the complex three-dimensional temperature and density structure of coronal active regions. The transfer equation is then cast in a form illustrating the terms which give rise to the attenuation or enhancement of the resonance-line intensity. The source function for helium-like oxygen (O VII) under coronal conditions is computed and discussed in terms of the relative importance of scattering.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 225
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  • 98
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    Solitons and second harmonic radiation in type III bursts (1978)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The emission at the second harmonic of the plasma frequency from self-consistent Langmuir solitons is calculated. The theory predicts, in a natural way, the observed transition from the region where the intensity is linearly proportional to the electron flux to the region where the radio intensity is proportional to the square of the electron flux. A detailed comparison of the radiation observed at the second harmonic for the burst of 18:10 UT March 31, 1976, with the one expected on the assumption of radiation from solitons, using the correlated in situ measurements of the electric fields at the second harmonic, and their spatial structure, provides strong evidence that, for the first time, Langmuir solitons have been observed in space.
    Keywords: SOLAR PHYSICS
    Type: Geophysical Research Letters; 5; Oct. 197
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  • 99
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    The thermal phase of a large solar flare (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: EUV and X-ray observations are used to derive the differential emission measures, temperatures, densities, radiative and conductive cooling rates, and thermal energy content of a class 2B flare that occurred on September 7, 1973. The results of the analysis indicate that (1) most of the flare plasma was at temperatures between 3 and 10 million degrees; (2) the peak temperature decreased with time from about 8 million K to 5 million K over a period of 3.5 hours; (3) the differential emission measure steadily decreased with time at nearly all temperatures; (4) both radiation and conduction were important cooling mechanisms for the plasma at temperatures above 100,000 K; and (5) a substantial amount of energy, of the order of 3 x 10 to the 31st power ergs, was deposited in the flare loops after flare maximum. The empirically determined flare parameters are compared with similar parameters derived from a simple theoretical loop model.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 225
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  • 100
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    Report on monitoring and support instruments for solar physics research from Spacelab (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The Quick Reaction and Special Purpose Facility Definition Team for Solar Physics Spacelab Payloads examined a variety of instruments to fulfill the following functions: (1) solar physics research appropriate to Spacelab, (2) correlative data for research in such fields as aeronomy, magnetospheric physics, ionospheric physics, meteorology and climatology, (3) target selection for activity alert monitoring and (4) pointing accuracy monitoring of Spacelab platforms. In this examination the team accepted a number of restrictions and qualifications: (1) the cost of such instruments must be low, so as not to adversely impact the development of new, research class instrumentation in the early Spacelab era; (2) the instruments should be of such a size that they each would occupy a small fraction of a pointing system, and (3) the weight and power consumption of the instruments should also be small. With these restrictions, the instruments chosen are: the visible light telescope and magnetograph, the extreme-ultraviolet telescope, and the solar irradiance monitor.
    Keywords: SOLAR PHYSICS
    Type: NASA-CR-159909
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