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  • SOLAR PHYSICS  (526)
  • 2015-2019
  • 1995-1999
  • 1980-1984  (310)
  • 1975-1979  (216)
  • 1970-1974
  • 1983  (310)
  • 1977  (216)
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  • 2015-2019
  • 1995-1999
  • 1980-1984  (310)
  • 1975-1979  (216)
  • 1970-1974
Year
  • 1
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    Enhancement of solar heavy nuclei at high energies in the 4 July 1974 event (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Relative abundances of energetic nuclei in the July 4, 1974, solar event are presented. The results show a marked enhancement of abundances that systematically increase with nuclear charge numbers in the range of the observation (Z between 6 and 26) for energies above 15 MeV/nucl. While such enhancements are commonly seen below 10 MeV/nucl, most observations at higher energies are found to be consistent with solar-system abundances. The energy spectrum of oxygen is observed to be significantly steeper than most other solar events studied in this energy region. It is proposed that these observations are characteristic of particle populations at energies of the order of 1 MeV/nucl and that the anomalous features observed may be the result of the high-energy extension of such a population that is commonly masked by other processes or populations that might occur in larger solar events.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 55; Dec. 197
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  • 2
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    Report on the Workshop on Intercomparison of Solar UV Irradiance Measurements and Related Instrument Calibration (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The knowledge of the absolute value of the solar ultraviolet irradiance did not improve very much during the rising phase of the solar cycle 21. The variations associated with the solar rotation period were observed by means of three satellites, namely, the Atmospheric Explorer E (AE-E), Nimbus 7 and the Solar Mesospheric Explorer (SME). Long-term variations related to the solar activity cycle are not well known. Values were deduced during the solar cycle 21 from the AE-E satellite and the rocket program performed by the Laboratory for Atmospheric and Space Physics leading to variations of about a factor of 2 around 150 nm but definitely less than 20 percent beyond 175 nm. Such low level of variation is still masked by the current uncertainties and reproducibility of the observations performed since 1976. The uncertainties of recent observations are reported with their discrepancies. The gaps between the current accuracy goals and the achievements are still very important. The challenge for the next three years is to improve both the accuracy and the precision of future observations at the level of the available irradiance standards and to measure quantitatively long-term variations of the order of a few percent. The main causes of these gaps are identified.
    Keywords: SOLAR PHYSICS
    Type: International Council of Scientific Unions Middle Atmosphere Program. Handbook for MAP, Vol. 8; p 45-51
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  • 3
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    Faraday rotation transients observed during solar occultation of the Helios spacecraft (1977)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: SOLAR PHYSICS
    Type: AFGL Contrib. Papers to the Study of Travelling Interplanetary Phenomena(1977; p 63-75
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  • 4
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    Electrodynamic coupling in magnetically confined stellar X-ray loops (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The solar coronal complex X-ray structure is now known to involve radiation loops that coincide spatially with the magnetic loops confining the radiating plasma. An effort is presently made to identify primary submodels involved in the global coupling between a mechanical energy reservoir of beta value greater than 1 and a contiguous site of X-ray activity whose beta value is lower than 1. The 'dynamo' model invoked establishes a quantitative connection between mechanical driver properties and the dimensions, field strength, and number density distribution of elemental magnetic loops.
    Keywords: SOLAR PHYSICS
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  • 5
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    Interpretation of vector magnetograph data including magneto-optic effects. I - Azimuth angle of the transverse field (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: In this paper, the presence of Faraday rotation in measurements of the orientation of a sunspot's transverse magnetic field is investigated. Using observations obtained with the Marshall Space Flight Center's (MSFC) vector magnetograph, the derived vector magnetic field of a simple, symmetric sunspot is used to calculate the degree of Faraday rotation in the azimuth of the transverse field as a function of wavelength from analytical expressions for the Stokes parameters. These results are then compared with the observed rotation of the field's azimuth which is derived from observations at different wavelengths within the Fe I 5250 A spectral line. From these comparisons, it is found: the observed rotation of the azimuth is simulated to a reasonable degree by the theoretical formulations if the line-formation parameter is varied over the sunspot; these variations are substantiated by the line-intensity data; for the MSFC system, Faraday rotation can be neglected for field strengths less than 1800 G and field inclinations greater than 45 deg; to minimize the effects of Faraday rotation in sunspot umbrae, MSFC magnetograph measurements must be made in the far wings of the Zeeman-sensitive spectral line.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 88; 51-64
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  • 6
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    Dynamics of a surge observed in the C IV and H alpha lines (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Time sequences of a surge have been obtained in Active Region 2701 during a coordinated SMY program, on October 2nd, 1980, while the MSDP spectrograph operated in H-alpha at the Meudon Solar Tower and the UVSP spectrometer on SMM observed in the 1548 A C IV resonance line. The cold (H-alpha) and hot (C IV) material follow the same channel, and the event lasts about 10 min in both lines. A good correlation is found between H-alpha and C IV velocities; radial velocities along the surge are in the range 40-60 km/s in both cases. The observations are consistent with the hypothesis that a pressure gradient drives the surge. The H-alpha data seem to indicate the presence of a shock wave in the chromosphere, while the C IV quantities (velocities, accelerations) vary on a very short time scale. Their maxima occur at some locations which could be interpreted as 'pinched' zones.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 127; 2, No; 337-344
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  • 7
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    Differences in the temporal variations of solar UV flux, 10.7-cm solar radio flux, sunspot number, and Ca-K plage data caused by solar rotation and active region evolution (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Attention is given to two types of temporal variations in the solar UV spectral irradiance caused by solar rotation and active region evolution. It is noted that the first type of dissimilar temporal behavior occurs when concentrations of solar active regions evolve at solar longitudes nearly 180 deg apart. Both the UV observations and modeled UV fluxes based on Ca-K plage data then exhibit pronounced 13-day periodicity, whereas the 10.7-cm solar radio flux and sunspot number exhibit quite dissimilar temporal variations. This type of dissimilarity is related to the modeled UV flux and has a dependence on the solar central meridian distance that is narrower than that for the 10.7-cm radio flux or for sunspot numbers. A second case of marked dissimilarity is seen when major new solar active regions arise and dominate the full-disk fluxes for several rotations. It is found that the strongest peaks in 10.7 cm and sunspot numbers tend to occur on their first rotation, for example, during major dips in the total solar irradiance, whereas the Ca-K plages and UV enhancements peak on the next rotation and then decay more slowly on subsequent rotations.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 9883-988
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  • 8
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    The stability of coronal loops - Finite-length and pressure-profile limits (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Results are described from a quickly converging, necessary-and-sufficient, MHD-stability test for coronal-loop models. The primary stabilizing influence arises from magnetic line tying at the photosphere, and this end conditions requires a series expansion of possible loop excitations. The stability boundary is shown to quickly approach a limit as the number of terms increases, providing a critical length for the loop in proportion to its transverse magnetic scale. Several models of force-free-field profiles are tested and the stability behavior of a localized current channel, embedded in an external current-free region, is shown to be superior to that of other, broader, current profiles. Pressure-gradient effects, leading to increased or decreased stability, are shown to be amplified by line tying. Long loops must either conduct low net current, or exhibit an axial-field reversal coexisting with a low-pressure core. The limits on stability depend on the magnetic aspect ratio, the plasma-to-magnetic pressure ratio, and the field orientation at the loop edge. Applications of these results to the structure of coronal loops are described.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 88; 163-177
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  • 9
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    Implications of high-energy neutron observations from solar flares (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The time-dependent flux of high-energy neutrons discovered from the solar flare of 1980 June 21 provides a new technique for determining the total number and energy spectrum of accelerated protons and nuclei at the sun. The implications of these observations on gamma-ray emission, relativistic electron spectrum and number, proton and electron energy contents, and the location of the interaction region are also examined.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 273; L41-L45
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  • 10
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    Fluid motions in the solar chromosphere-corona transition region. IV - Mass motions over sunspot umbrae (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 273; 374-380
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  • 11
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    Solar irradiance variations. II - Analysis of the extreme ultraviolet measurements onboard the Atmosphere Explorer E satellite (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Five of the extreme ultraviolet channels (L-alpha, L-beta, He I, He II, Fe XV) measuring irradiance fluctuations on board the AE-E satellite between 1977 and 1980 have been studied in detail. It is shown that the daily variations correspond very closely to the daily variations in solar radio emission (F10.7), but that the UV data are afflicted with serious and to date unrecognized calibration changes during the period of operation of the instruments. In order to correct for these changes, a statistical analysis is carried out, and a set of corrections to the raw data is suggested. The resulting, now uniform, data are then compared with rocket measurements (L-alpha) and data acquired onboard the AE-C satellite (L-beta). Finally the remaining discrepancies are discussed. After concluding that they are below the overall level of uncertainties, a first-order 10-year run of EUV irradiances derived from F10.7 data is proposed. This estimate includes the ratio of irradiance levels between the maxima of solar cycles 20 and 21 and the intervening minimum.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 9037-905
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  • 12
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    Determining the solar wind speed above active regions using remote radio-wave observations (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A new technique has made it possible to measure the velocity of portions of the solar wind during its flow outward from the sun. This analysis utilizes spacecraft (ISEE-3) observations of radio emission generated in regions of the solar wind associated with solar active regions. By tracking the source of these radio waves over periods of days, it is possible to measure the motion of the emission regions. Evidence of solar wind acceleration during this outward flow, consistent with theoretical models, has also been obtained.
    Keywords: SOLAR PHYSICS
    Type: Science (ISSN 0036-8075); 222; 506-508
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  • 13
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    Computer solutions for studying correlations between solar magnetic fields and Skylab X-ray observations (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A method is described which correlates the NASA-Marshall Space Flight Center (MSFC) Image Data Processing System (IDAPS) and MSFC magnetograph data to X-ray and H-alpha observations from the Skylab mission. Solutions of Laplace's equation in three dimensions, based on the magnetograph data, are convolved with observed X-ray and H-alpha regions. Matched filtering (template matching) provides a best fit of the observed X-ray regions to the computed total magnetic vector magnitude between 10,000 and 15,000 km above the photosphere.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 53; July 197
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  • 14
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    The spiral configuration of sunspot magnetic fields (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Distributions of circularly and linearly polarized intensities are computed using an analytical magnetic field model for an isolated sunspot, and these intensity distributions are compared with observed intensities in all Stokes parameters in the 5250-A line measured with the Marshall Space Flight Center's vector magnetograph. The qualitative agreement between measured and calculated linearly polarized intensity distributions is discussed with regard to implications as to the configuration of the transverse magnetic field of the isolated sunspot.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 53; July 197
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  • 15
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    A search for a turbulent-free region in the solar transition zone (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A search for a turbulence-free transition-zone region was conducted. The data used were spectra recorded by a slit spectrograph on Skylab. It was found that the nonthermal turbulent motions are smallest in certain active regions and quiescent prominences. The spectra of one such region, a quiescent prominence, are discussed. The nonthermal turbulence in the region is between about 2 and 7 km/s. Therefore, the widths of lines emitted by transition-zone ions are determined primarily by the ion temperature. To within the experimental error, temperatures derived from the line widths are equal to the temperatures of maximum emitting efficiency obtained using the ionization equilibrium calculations of Jordan (1969).
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 216
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  • 16
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    XUV spectra of the 1973 June 15 solar flare observed from Skylab. II - Intersystem and forbidden transitions in transition zone and coronal ions (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 215
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  • 17
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    On the problem of density diagnostics for the EUV spectrum of the solar transition zone (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Spectral-line ratios that may be used to determine the electron temperature and density in the solar transition zone and corona are identified. The problem of interpreting the intensity ratios of C III lines observed in Skylab EUV limb spectra is considered. It is shown that the intensity distribution with height above the solar limb of the 1176-A C III lines is different from that of the 1909-A C III lines in the Skylab spectra, suggesting that model atmospheres must be folded into the C III calculations for proper interpretation of the data. Possible reasons for the differences in the intensity distributions and widths of the 1176-A and 1909-A lines are discussed along with an application to the analogous lines of Si III.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 58; 1-2,; June 197
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  • 18
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    XUV spectra of the 1973 June 15 solar flare observed from Skylab. I - Allowed transitions in chromospheric and transition zone ions (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 215
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  • 19
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    Magnetic holes in the solar wind (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An analysis of high-resolution magnetic field measurements from the Goddard Space Flight Center magnetometer on Explorer 43 showed that low magnetic field intensities (less than 1 gamma) in the solar wind at 1 AU occur as distinct depressions, or 'holes', in otherwise nearly average conditions. These magnetic holes are new kinetic scale phenomena, having a characteristic dimension of the order of 20,000 km. They occurred at a rate of 1.5/d in the 18-day interval (March 18 to April 6, 1971) that was considered. Most magnetic holes are characterized by both a depression in /B/ and a change in the magnetic field direction, and some of these are possibly the result of magnetic merging. However, in other cases the direction, does not change; such holes are not due to merging but might be a diamagnetic effect due to localized plasma inhomogeneities.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; May 1
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  • 20
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    A search for auroral type motions in solar flares (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Because of analogies between auroras and solar flares, and because of well-established motion along auroras (the so-called westward travelling surge), one might expect systematic motion of brightness to occur along flare ribbons. The Sacramento Peak Observatory flare records of 37 double-ribbon solar flares observed from 1968 to 1972 were examined for evidence of such systematic motion, but results of the investigation were negative.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; May 1
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  • 21
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    High resolution spectroscopy of the disk chromosphere. V - Space-time variations observed simultaneously in seven lines (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Time sequence spectroscopic observations of the quiet solar chromosphere along a 200 Mm strip near the center of the disk were reduced to obtain 30 min of data. Oscillations appear in most of the observations in selected photospheric and chromospheric lines, but rarely in continuum observations. At a given point, the oscillations may be prominent or weak, they are never regular in time, and there is no unique relationship between the amplitudes at different heights. There are several examples of granules which apparently excite a burst of short period oscillations. By considering the line shift and intensity variations of all the lines, a working model is derived for the velocity field and related temperature variation.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 57; 1-2,; May 1977
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  • 22
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    On coronal temperatures, temperature gradients and compositions (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Average solar wind properties at 1 AU either alone or together with the electron density distribution are used to obtain or review some results that relate coronal temperatures, temperature gradients, and compositions. Measured values of the temperature (T) and the temperature gradient parameter are used to find compositions that satisfy the equations used to obtain the results. The total energy equation may be satisfied if the thermal conductivity is reduced by considerable depletions of H(+) in the corona. The hydrostatic approximation (momentum equation) for the electron density distribution appears to require considerable depletions of H(+) in the corona.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 51; Mar. 197
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  • 23
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    Structure of coronal holes from UV and radio observations (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: EUV (Fe XV at 284 A) and radio (at 169 and 408 MHz) observations were made of the coronal hole on May 31, 1973. An inhomogeneous model consisting of hot (a temperature of about 2 x 10 to the 6th K) elements covering 10% of the hole surface surrounded by regions of colder gas (a temperature of about 8 x 10 to the 5th K) is able to explain both observations.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 51; Jan
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  • 24
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    Physical processes determining the chromospheric temperature distribution (1977)
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    Publication Date: 2011-08-17
    Description: It is demonstrated that short period acoustic waves appear adequate to heat the low chromosphere in the region just above the temperature minimum, these waves are unlikely to provide sufficient energy to heat the chromosphere above tau-5000 A(normal) less than 10 to the -6th. Calculations also show that the electron density to H density ratio from chromospheric models is too low for the H2 molecule to affect the population of H(-).
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 51; Jan
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  • 25
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    Preliminary analysis of coronal electron content measurements from spacecraft Helios A around first solar occultation (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Steady-state and dynamical features of the electron density distribution in the solar corona emerge from a preliminary analysis of Helios A electron content measurements. There are strong indications that correlations can be established with earth-bound K-coronagraph measurements.
    Keywords: SOLAR PHYSICS
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  • 26
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    The 3s-3p and 3p-3d lines of Mg II observed above the solar limb from Skylab (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 212
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  • 27
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    The coronal temperature and nonthermal motions in a coronal hole compared with other solar regions (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The coronal lines Si VIII (1446 A), Fe X (1463 A), Fe XI (1467 A), and Fe XII (1242 A and 1349 A) were observed above the limb over a quiet region, a coronal hole, and two active regions. The lines emitted at temperatures greater than 1 million K; i.e., the iron lines, are not observed in the coronal-hole spectra, so the indication is that in the coronal hole most of the plasma is at a temperature of less than 1 million K. The emission measures and column densities of the lines are derived from available atomic cross-section data, and the results are discussed. The nonthermal velocities in the coronal hole and quiet region are about 20 km/s. The velocities in the active regions are substantially less.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 212
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  • 28
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    Chromospheric limb spectra from Skylab - 2000 to 3200 A (1977)
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    Publication Date: 2011-08-17
    Description: Chromospheric limb spectra of a quiet-sun region between 2000 and 3200 A recorded by the normal-incidence spectrograph on Skylab are discussed. The spectral resolution is 0.12 A, and the projected slit area on the sun is 2 by 60 arcsec. A list of lines with wavelengths, identifications, and absolute intensities is given for the spectrum recorded at +4 arcsec outside the white-light limb. The intensity behavior outside the limb is shown for lines of the ions C II, Si II, Cr II, Mn II, Fe II, Fe III, Co II, and Ni II. The widths of the intersystem lines of Si II and C II increase monotonically with height above the limb. The full width at half-maximum of the Si II lines increases from 0.034 A at the limb to 0.27 A at +12 arcsec above the limb. The widths of the C II lines increase from 0.17 A at +2 arcsec to 0.31 A at +12 arcsec.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal Supplement Series; 33; Jan. 197
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  • 29
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    Nonlinear Alfven waves in high-speed solar wind streams (1977)
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    Publication Date: 2011-08-17
    Description: A nonlinear proton distribution function that is an exact stationary solution of the nonlinear Vlasov equation and Maxwell's equations and which supports a single nonlinear transverse Alfven (ion cyclotron) wave that is circularly polarized and nondispersive is proposed for most of the observations during high-speed solar wind streams. This nonlinear distribution removes the strong Alfven wave instability, inconsistent with the persistence of the observed proton distribution functions in high-speed streams, found by the linear stability analysis. Model temperature anisotropies and drift velocities of the two spatially inhomogeneous bi-Maxwellian components are consistent with typical proton velocity distributions measured in high-speed streams at 1 AU. Two derived relations for each of the wave number and the phase velocity of the wave are obeyed within experimental uncertainties by two typical proton measurements. Our model also predicts that the alpha particle bulk flow velocity exceeds the proton particle bulk flow velocity, as is observed.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; Feb. 1
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  • 30
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    Approximations for proton excitation of coronal ion fine structure (1977)
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    Publication Date: 2011-08-17
    Description: Explicit approximations that yield proton excitation cross sections and rate coefficients for fine-structure transitions in a wide variety of ions over the low and intermediate energy ranges are obtained in terms of the electric quadrupole transition probability and quadrupole radial integral of a given ion. The range of applicability of these approximations is discussed, and comparisons are made with available cross sections and rate coefficients. Values of quadrupole radial integrals are given for ground configurations of even-Z elements in higher stages of ionization. Proton excitation rate coefficients are computed for coronal transitions involving fine-structure levels in the ions Fe XIII, Fe XV, Fe XVIII, Fe XXI, and Ca XIII.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 54; 1, Ja; Jan. 197
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  • 31
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    Viking S-band Doppler RMS phase fluctuations used to calibrate the mean 1976 equatorial corona (1977)
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    Publication Date: 2011-08-17
    Description: Viking S-band Doppler RMS phase fluctuations (noise) and comparisons of Viking Doppler noise to Viking differenced S-X range measurements are used to construct a mean equatorial electron density model for 1976. Using Pioneer Doppler noise results (at high heliographic latitudes, also from 1976), an equivalent nonequatorial electron density model is approximated.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 152-166
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  • 32
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    Solar flare activity - Evidence for large-scale changes in the past (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An analysis of radar and photographic meteor data and of spacecraft meteoroid-penetration data indicates that there probably has not been a large increase in meteoroid impact rates in the last 10,000 yr. The solar-flare tracks observed in the glass linings of meteoroid impact pits on lunar rock 15205 are therefore reanalyzed assuming a meteoroid flux that is constant in time. Based on this assumption, the data suggest that the production rate of Fe-group solar-flare tracks may have varied by as much as a factor of 50 on a time scale of about 10,000 yr. No independently obtained data are known to require conflict with this interpretation. Confidence in this conclusion is somewhat qualified by the experimental and analytical uncertainties involved, but the conclusion nevertheless remains the present 'best' explanation for the observed data trends.
    Keywords: SOLAR PHYSICS
    Type: Icarus; 32; Sept
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  • 33
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    An unusual aspect of solar wind speed variations during solar cycle 20 (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Geomagnetic records from 1868 through 1975 indicate that geomagnetic activity during 1973-1975 was unusually enhanced for that phase of the sunspot cycle (5-7 years after solar maximum). Previous work indicates that long-term variations in geomagnetic activity are closely coupled to long-term variations in the bulk flow speed of the solar wind. Thus, it is inferred that reported averages of the solar-wind speed for the 1973-1975 era are unusually large for that phase of the sunspot cycle.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; Aug. 1
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  • 34
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    A reexamination of two-fluid solar wind models (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The two-fluid solar-wind equations have been solved by a method which is approximately 50 times faster than any previously developed, through the use of asymptotic expansions which are self-consistently iterated upon to find a solution that passes through the critical point. The energy assumptions in two-fluid solar-wind models are reexamined, and the conclusions are as follows: (1) proton thermal conduction may not be neglected, (2) the Coulomb logarithm must be calculated as a function of radius, and (3) the electron and proton temperatures at the base need not be equal, even when the time scale for energy exchange between the species is an order of magnitude smaller than the expansion time at the base. It is possible to reproduce reasonable quiet-time solar-wind parameters at 1 AU, but only if the proton temperature is approximately twice the electron temperature at 1 solar radius. This may indicate that extended proton heating is important in the outer solar corona. Winds with velocities at 1 AU of 450 km/s are generated without nonthermal energy deposition but require high proton temperatures as well as very low densities at the base. Higher-velocity solutions are not possible in a spherically symmetric geometry for reasonable particle fluxes at 1 AU, and it is suggested that these higher-velocity states probably require additional heating, acceleration mechanisms, or nonradial flow.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; Aug. 1
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  • 35
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    Radio observations of interplanetary magnetic field structures out of the ecliptic (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Observations of the out-of-ecliptic trajectories of type III solar radio bursts have been obtained from simultaneous direction-finding measurements in two independent satellite experiments, IMP-6 with spin plane in the ecliptic and RAE-2 with spin plane normal to the ecliptic. Burst-exciter trajectories were observed which originated at the active region and then crossed the ecliptic plane at about 0.8 AU. A considerable large-scale north-south component of the interplanetary magnetic field followed by the exciters is found. The apparent north-south and east-west angular source sizes observed by the two spacecraft are approximately equal, and range from 25 deg at 600 kHz to 110 deg at 80 kHz.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 52; May 1977
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  • 36
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    A possible edge effect in enhanced network (1977)
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    Publication Date: 2011-08-17
    Description: K-line observations of enhanced network taken with the NASA/SPO Multichannel Spectrometer on September 28, 1975, in support of OSO-8 are discussed. The data show a correlation between core brightness and asymmetry for spatial scans which cross enhanced network boundaries. The implications of this result concerning mass flow in and near supergranule boundaries are discussed.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 52; May 1977
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  • 37
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    Atmospheric turbulence and the apparent instantaneous diameter of the sun (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Astrometric data are perturbed by turbulent density fluctuations in the atmosphere over the frequency range from 0.0001 to 10 Hz by amounts that would limit the accuracy of solar-diameter measures significantly. Power spectra of the perturbations are compared with meteorological data to argue that thermal turbulence is dominant above 0.001 Hz and that mechanical turbulence (weather) is important below that frequency. Noise power in astrometry should be comparable under night or day conditions, but site location may be important for the strength of slowly passing waves.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 59; 2, Ju; July 197
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  • 38
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    Multispacecraft observations of microscale fluctuations in the solar wind (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Data from the Explorer 33 and 35 satellites were used to study Alfvenic fluctuations (i.e., fluctuations with a high correlation between perturbation in velocity and magnetic field) in the solar wind. It was found that the average minimum variance method does not give a good estimate of the phase front direction of these fluctuations. There is a distinct class of Alfvenic fluctuations with phase planes nearly parallel to the mean field B sub 0. The characteristic length of the phase fronts of the fluctuations is probably significantly greater than 50 R-E. It is concluded that since tangential discontinuities and possibly other types of static structures appear in Alfvenic fluctuations, these fluctuations are not solely Alfven waves.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; July 1
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  • 39
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    Preferred solar wind emitting longitudes on the sun (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: During the 11 1/2-year period from July 1964 through December 1975, high- and low-speed solar wind flows originated from preferred solar longitudes. The preferred longitude effect was most pronounced from 1970 onward but was also evident in the years preceding 1970. The most pronounced modulation in average solar wind speed with longitude (approximately 20%) was obtained when it was assumed that the synodic rotation period of the sun is 27.025 days. Some deep internal structure in the sun must ultimately be responsible for these long-lived longitudinal effects, which appear to rotate rigidly with the sun.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; June 1
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  • 40
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    A solar plasma stream measured by DRVID and dual-frequency range and Doppler radio metric data (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: S- and X-band DRVID, S- and X-band dual-frequency range (SX(p)), and Doppler (SX(p)) measured a 15-fold increase in the line-of-sight electron content of the solar plasma above the normal plasma background. A general increase in the plasma electron content continued for nearly 50 hours: it started about 12:00 (GMT) on 12 March 1976 and continued to grow until 17:00 (GMT) on 14 March. For the next 55 hours, between 17:00 (GMT) on 14 March to 00:54 (GMT) on 17 March, the plasma level diminished as the background level was approached. Not only were the temporal changes and absolute level of the plasma content measured but the measurements were also used to ascertain the mean-plasma-concentration location: it was estimated to be 4.1 light minutes from earth.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 43-54
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  • 41
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    Solar polar coronal hole - A mathematical simulation (1977)
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    Publication Date: 2011-08-17
    Description: The northern polar region of the sun was studied during July 1973 by Munro and Jackson through use of the white-light coronagraph and the X-ray photographs produced by the Skylab mission. They described the northern polar hole as nearly axisymmetric and gave the geometry and density distribution under this approximation. The present work gives quasi-radial approximation to the full magnetohydrodynamic equations for axisymmetric, polytropic solar wind flow to simulate this polar hole, with the benefit that model temperature and magnetic field intensities and distributions in this particular polar hole can be deduced. It is concluded that from 2 out to 5 solar radii the temperature varies only slightly with radius, but is larger near the center of the polar hole than at the edge. It is also found that the magnetic field intensity at 2 solar radii could be about 1 gauss at the center of the hole, decreasing toward the edge of the hole. If this is extrapolated to the surface, a field as high as 20 gauss is suggested.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 217
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  • 42
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    Evidence for a structure-free state at high solar wind speeds (1977)
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    Publication Date: 2011-08-17
    Description: The variability of the basic solar wind flow parameters in highand low-speed flows is submitted to a statistical analysis. Particular attention is given to the uniformity of solar wind high-speed flow conditions by comparing them with those of the low-speed so-called quiet solar wind. With the exception of the solar wind bulk velocity, the average fractional variation of each of a selected sample of basic solar wind parameters is found to be substantially larger during low-speed flow conditions than during high-speed flow conditions at 1 AU. As a statistical ensemble of events, the only thing steady and uniform about low-speed conditions is the bulk velocity. In all other respects, high-speed flows form a much more uniform ensemble of solar wind conditions than do the low-speed flows. It is concluded that the use of average high-speed flow parameters for comparison with steady-state spherically symmetric models of the coronal expansion is meaningful.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; Apr. 1
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  • 43
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    Viking Doppler noise used to determine the radial dependence of electron density in the extended corona (1977)
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    Publication Date: 2011-08-17
    Description: The common form for radial dependence of electron density in the extended corona is given. By assuming proportionality between Doppler noise and integrated signal path electron density, Viking Doppler noise can be used to solve for a numerical value of X.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 167-171
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  • 44
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    Solar plasma: Viking 1975 interplanetary spacecraft dual-frequency Doppler data (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Viking 1975 interplanetary S- and X-band Doppler data are surveyed. These data show consistency with differenced range versus integrated Doppler (DRVID) data when there is solar plasma and with Faraday rotation data otherwise. An increase of solar plasma effects with decreasing sun-earth-probe (SEP) angle (approaching Mars orbit insertion) is demonstrated. The 2-way/3-way data indicate a homogeneous solar plasma structure over a 8,000-km spread. Occasional cycle slips in the data are pinpointed and tabulated.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 204-223
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  • 45
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    Precision insolation measurement under field conditions (1977)
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    Publication Date: 2011-08-17
    Description: Work at the Jet Propulsion Laboratory had resulted in the development of a primary absolute cavity radiometer (PACRAD), which was recently accepted as an international standard of irradiance. The development of an wall-weather, field-worthy solar radiometer based on the PACRAD is discussed, and its calibration stability over a two-year period in the field is described.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 169-175
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  • 46
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    The solar spectrum in the vicinity of the Si IV lines at 1122 and 1128 A (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 61; 2, Oc; Oct. 197
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  • 47
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    On coronal Fe abundances and temperatures from XUV emission lines (1977)
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    Publication Date: 2011-08-17
    Description: Data obtained by the OSO-7 spectroheliograph on strong XUV lines of five different Fe ions from the outer equatorial corona are presented. Interpretation of the data with a spherically symmetric model atmosphere gives average ion abundances for lines of sight at 0.3 solar radii from the limb. Fe XVI is usually more abundant than Fe XV, XIV, XII and IX, but there are times when Fe XII is more abundant than the other ions. The deviation of measured relative abundances of Fe XII, XIV, and XVI from predictions of ionization equilibrium at one temperature seems to indicate that there are appreciable temperature variations along lines of sight. Element abundances are very uncertain since they appear to depend so heavily on likely but unknown density irregularities along lines of sight.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 53; Aug. 197
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  • 48
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    An empirical model for the solar wind velocity (1977)
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    Publication Date: 2011-08-17
    Description: An analytic expression for the average radial component of the Solar Wind velocity between 1 solar radius and 1 AU is developed. The model is constructed by assuming the conservation of particle flow in the Solar Wind and application of a twelve-year average measured value of the Solar Wind radial velocity at 1 AU.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 130-134
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  • 49
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    A first-principles derivation of Doppler noise expected from solar wind density fluctuations (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The level of Doppler noise (DN) expected from solar wind (SW) density fluctuations (DF) is derived beginning with the expression for refractive index variations. The calculation takes account of up and downlink paths and of the method actually used to produce the DN values. The usual assumptions that the DF are frozen in, that the large-scale radial variation can be separated from the DF, that the DF power spectrum is a power law with outer scale k sub 0 and that the DF are homogeneous on scales less than 2c delta t, delta t = sample time, are made. The result agrees quite well with previous observations of DN. Corrections for the finite number of points used in the actual algorithm are discussed.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 42-53
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  • 50
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    A preliminary analysis of Viking S-X Doppler data and comparison to results of Mariner 6, 7, and 9 DRVID measurements of the solar wind turbulence (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: S-X Doppler data obtained during more than 135 Viking passes from Aug. 3 to Dec. 15, 1976 were analyzed and compared with data from previous investigations using Mariner differenced range versus integrated Doppler to determine changes in the turbulence over the sunspot cycle. A comparison of the data indicates that: (1) electron density fluctuations decline with heliocentric distance; (2) the level of turbulence may be a factor of two lower near sunspot minimum than at maximum; and (3) the spectrum of the fluctuations may be steeper near sunspot minimum. The expected range error for various time scales and geometries is derived from the results.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network, Vol. 39; p 23-29
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  • 51
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    Hydromagnetic waves, turbulence, and collisionless processes in the interplanetary medium (1983)
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    Publication Date: 2011-08-18
    Description: An extended discussion is conducted concerning the origin and evolution of interplanetary hydromagnetic waves and turbulence, and their influence on the large scale dynamics of the solar wind. The solar wind is at present the preeminent medium for the study of hydromagnetic waves and turbulence, providing an opportunity for advancement of understanding of the most fundamental processes of the astrophysical plasmas. All interplanetary fluctuations whose time scale is observed to be greater than 1 sec can be regarded as hydromagnetic fluctuations. It has been found to be simplest, and generally very satisfactory, to model interplanetary variations as fluctuations in an MHD fluid. Attention is given to the classification of wave modes, geometrical hydromagnetics, Alfven wave pressure, rugged invariants, and the kinetic theory of collisionless processes.
    Keywords: SOLAR PHYSICS
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  • 52
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    Behavior of transition-region lines during impulsive solar flares (1983)
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    Publication Date: 2011-08-18
    Description: The emissions observed in lines originating in the transition-region plasma, particularly during impulsive flares, are investigated using data collected by the Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission. Data concerning lines from ions such as Si II, C IV, Si IV, O V, and Fe XXI are analyzed. Topics examined include the transition region away from sunspots, oscillatory motions above sunspots, the shape of the transition region, the transition region during flares, and O V and Fe XXI during flare flash phases.
    Keywords: SOLAR PHYSICS
    Type: (ISSN 0038-0938)
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  • 53
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    Gamma-ray lines and neutrons from solar flares (1983)
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    Publication Date: 2011-08-18
    Description: The energy spectrum of accelerated protons and nuclei at the site of a limb flare was derived by a technique, using observations of the time dependent flux of high energy neutrons at the earth. This energy spectrum is very similar to the energy spectra of 7 disk flares for which the accelerated particle spectra was previously derived using observations of 4 to 7 MeV to 2.223 MeV fluence ratios. The implied spectra for all of these flares are too steep to produce any significant amount of radiation from pi meson decay. It is suggested that the observed 10 MeV gamma rays from the flare are bremsstrahlung of relativistic electrons. Previously announced in STAR as N83-19695
    Keywords: SOLAR PHYSICS
    Type: (ISSN 0038-0938)
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  • 54
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    A comparison of coronal and interplanetary current sheet inclinations (1983)
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    Publication Date: 2011-08-18
    Description: The HAO white light K-coronameter observations show that the inclination of the heliospheric current sheet at the base of the corona can be both large (nearly vertical with respect to the solar equator) or small during Cararington rotations 1660 - 1666 and even on a single solar rotation. Voyager 1 and 2 magnetic field observations of crossing of the heliospheric current sheet at distances from the sun of 1.4 and 2.8 AU. Two cases are considered, one in which the corresponding coronameter data indicate a nearly vertical (north-south) current sheet and another in which a nearly horizontal, near equatorial current sheet is indicated. For the crossings of the vertical current sheet, a variance analysis based on hour averages of the magnetic field data gave a minimum variance direction consistent with a steep inclination. The horizontal current sheet was observed by Voyager as a region of mixed polarity and low speeds lasting several days, consistent with multiple crossings of a horizontal but irregular and fluctuating current sheet at 1.4 AU. However, variance analysis of individual current sheet crossings in this interval using 1.92 see averages did not give minimum variance directions consistent with a horizontal current sheet. Previously announced in STAR as N83-31566
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; Oct. 1
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  • 55
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    The solar O III spectrum. II - Longer wavelengths, line widths, and the He II Lyman alpha radiation field (1983)
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    Publication Date: 2011-08-18
    Description: The solar O III spectrum above 900 A is analyzed, including several visible and infrared lines which are important in nebular studies. The dependence of the line intensities on the rate of photoexcitation by He Ly-alpha is determined, and the observability of these lines in the solar spectrum is studied. The impact approximation is employed to calculate the expected line widths of the stronger solar O III lines. The photoexciting field at 304 A calculated from the observed intensities of the O III lines below 900 A (Bhatia et al., 1982) is compared with the field predicted by a recent model (Avrett et al., 1976). It is shown that additional radiation trapping must be present beyond that given by this model.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 53; Sept
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  • 56
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    Measurements on a shock wave generated by a solar flare (1983)
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    Publication Date: 2011-08-18
    Description: It is shown that path-integrated radio-scattering measurements of the solar wind velocity yield higher estimates than those of point measurements. The post-shock speed is determined from radio scattering measurements by selection of the maximum of the radio-scattering deduced from the velocity-time curve, whereas velocity points on the rising edge of the shock underestimate the post-shock gas velocity, and therefore the shock speed. However, it is suggested that large uncertainties reside in using radio techniques for measurements of parameters of the shock wave, and the uncertainties may be large enough to encompass the lower velocity values calculated by a point method of measurement.
    Keywords: SOLAR PHYSICS
    Type: Nature (ISSN 0028-0836); 304; Aug. 25
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  • 57
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    Solar radius change between 1925 and 1979 (1983)
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    Publication Date: 2011-08-18
    Description: From an analysis of numerous reports from different locations on the duration of totality of the solar eclipses on January 24, 1925, and February 26, 1979, it is found that the solar radius at the earlier date was 0.5 arcsec (or 375 km) larger than at the later date. The correction to the standard solar radius found for each eclipse is different when different subsets of the observations are used (for example, edge of path of totality timings compared with central timings). This is seen as suggesting the existence of systematic inaccuracies in our knowledge of the lunar figure. The differences between the corrections for both eclipses, however, are very similar for all subsets considered, indicating that changes of the solar size may be reliably inferred despite the existence of the lunar figure errors so long as there is proper consideration of the distribution of the observations. These results are regarded as strong evidence in support of the occurrence of solar radius changes on shorter than evolutionary time scales.
    Keywords: SOLAR PHYSICS
    Type: Nature (ISSN 0028-0836); 304; Aug. 11
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  • 58
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    Solar oscillations with 13-day period (1983)
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    Publication Date: 2011-08-18
    Description: Reference is made to the solar observations made by Claverie et al. (1982) over a three-month period in the summer of 1981 which show oscillatory velocity with a period of 13.1 days and amplitude of 6.6 m/s. These investigators reject the possibility that they see the Doppler shift from a radial oscillation, because the amplitude is implausibly large. They also do not believe that their signal was induced by solar magnetic fields, since typical mean solar fields are too small. Photo-electric drift-scan measurements of the solar diameter and full-disk magnetograms taken at Kitt Peak National Observatory are examined here for evidence of variations corresponding to the velocity oscillations of the 13.1-day period. An upper limit on radius variations is reported which is a factor of six below the amplitude needed to explain the velocity observations as a radial oscillation. Attention is also given to the possible role of the rotation of large-scale surface magnetic features.
    Keywords: SOLAR PHYSICS
    Type: Nature (ISSN 0028-0836); 304; Aug. 11
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  • 59
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    Formation of the Cl I line at 1351 A in the solar chromosphere (1983)
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    Publication Date: 2011-08-18
    Description: The formation of the multiplet containing the Cl I 1351 A line is investigated due to the unusual brightness of this line. It is determined that this line is formed via a fluorescence effect driven by the 1335 A line of C II. Non-LTE calculations including this effect are found to agree with the observed line intensity. It is shown that the 1347 and 1363 A lines of Cl I do not benefit from this effect and they are predicted to be approximately 100 times weaker.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 266
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  • 60
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    Observations of solar oscillations of low and intermediate degree (1983)
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    Publication Date: 2011-08-18
    Description: Measurements are presented of solar velocity oscillations with spherical harmonic degree 1-139 and angular order approximately 0. With an amplitude sensitivity of approximately 2 cm/s, trapped acoustic wave modes of radial orders 2-26 are observed at frequencies between 1.7 and 5.5 mHz. The radial order identifications of low-degree modes previously inferred from theory are confirmed. Only marginal evidence of long-period, gravity-mode oscillations is found.
    Keywords: SOLAR PHYSICS
    Type: Nature; 302; Mar. 3
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  • 61
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    Magnetic canopies in unipolar regions (1983)
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    Publication Date: 2011-08-18
    Description: Base-height statistics are presented for magnetic canopies in six unipolar magnetic regions which were observed near the limb with the Kitt Peak Vacuum Telescope and Diode Array Magnetograph during the period 25 April-3 July, 1980. As in earlier studies, extensive areas are found to be covered by low-lying canopies.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 87; Aug. 198
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  • 62
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    Corotating pressure waves without fast streams in the solar wind (1983)
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    Publication Date: 2011-08-18
    Description: Voyager 1 and 2 magnetic field and plasma data are presented which demonstrate the existence of large scale, corotating, non-linear pressure waves between 2 AU and 4 AU that are not accompanied by fast streams. The pressure waves are presumed to be generated by corotating streams near the sun. For two of the three pressure waves that are discussed, the absence of a stream is probably a real, physical effect, viz., a consequence of deceleration of the stream by the associated compression wave. For the third pressure wave, the apparent absence of a stream may be a geometrical effect; it is likely that the stream was at latitudes just above those of the spacecraft, while the associated shocks and compression wave extended over a broader range of latitudes so that they could be observed by the spacecraft. It is suggested that the development of large-scale non-linear pressure waves at the expense of the kinetic energy of streams produces a qualitative change in the solar wind in the outer heliosphere. Within a few AU the quasi-stationary solar wind structure is determined by corotating streams whose structure is determined by the boundary conditions near the sun. Previously announced in STAR as N83-19694
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; Aug. 1
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  • 63
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    Microwave and hard X-ray observations of a solar flare with a time resolution better than 100 ms (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Simultaneous microwave and X-ray observations are presented for a solar flare detected on 1980 May 8 starting at 1937 UT. The X-ray observations were made with the Hard X-ray Burst Spectrometer on the Solar Maximum Mission and covered the energy range from 28-490 keV with a time resolution of 10 ms. The microwave observations were made with the 5 and 45 foot antennas at the Itapetinga Radio Obervatory at frequencies of 7 and 22 GHz, with time resolutions of 100 ms and 1 ms respectively. Detailed correlation analysis of the different time profiles of the event show that the major impulsive in the X-ray flux preceded the corresponding microwave peaks at 22 GHz by about 240 ms. For this particular burst the 22 GHz peaks preceded the 7 GHz by about 1.5s. Observed delays of the microwave peaks are too large for a simple electron beam model but they can be reconciled with the speeds of shock waves in a thermal model. Previously announced in STAR as N82-30215
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 84; April 19
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  • 64
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    The isotopic composition of solar flare noble gases (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The relative elemental and isotopic abundances of noble gases provide insights into a number of topics related to the solar system. Neon is in many ways the most diagnostic of the noble gases. The diagnostic character is mainly related to the variation in the relative abundance of the two most abundant neon isotopes, Ne-20 and Ne-22. The available evidence suggests that trapped neon found in meteorites and in lunar samples consists of as many as five isotopically distinct components, including neon A, B, C, D, and E. Neon B has been shown to be due to solar wind neon which has been directly implanted into the material found in a meteorite. It appears that neon E is extrasolar in origin. There exist ambiguities regarding the origins of the remaining three components. The present investigation is concerned with a reexamination of the existing data in an effort to eliminate or at least clarify these ambiguities. It is found that neon C is apparently due to directly implanted, low-energy solar flare neon nuclei.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 266
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  • 65
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    Electron densities in solar flares from line ratios of Ca XVII (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 60; 2, Se; Sept
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  • 66
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    Measuring solar wind velocity with spacecraft phase scintillations (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The measurement of spacecraft phase scintillations with a coherent dual-frequency radio system permits solar-wind velocity measurements based on multiple-station phase scintillations. Advantages of measuring solar-wind velocity on the basis of multiple-station phase scintillations are discussed with respect to amplitude scintillations. These advantages include the ability to carry out observations closer to the sun, a much wider range of possible baselines, a lower S/N ratio for long-baseline phase measurements, and a wider range of antenna sizes and receiver noise temperatures. NASA antennas particularly suitable for these measurements are identified, and observations with the coherent S/X radio system aboard various NASA spacecraft intended for deep-space missions are proposed.
    Keywords: SOLAR PHYSICS
    Type: Nature; 266; Apr. 7
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  • 67
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    Planetary tides during the Maunder Sunspot Minimum (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: In order to test the tidal theory of sunspots, sun-centered planetary conjunctions and tidal potentials are reconstructed for the period of the Maunder Minimum (1645 to 1715). These are found to be effectively indistinguishable from patterns of conjunctions and power spectra of tidal potential in the modern era of a well-established 11-yr sunspot cycle. The pattern of planetary tidal forces during the Maunder Minimum is then reconstructed to investigate the possibility that multiple-planet forces were somehow fortuituously cancelled at that time; i.e., the positions of the slower moving planets in the late 17th and early 18th centuries were such that conjunctions and tidal potentials were reduced in number and force. Calculations of daily positions for Mercury, Venus, earth, and Jupiter as well as daily values of the tidal potential for the period from 1450 to 2000 indicate no striking dissimilarities between the time of the Maunder Minimum and any other period considered.
    Keywords: SOLAR PHYSICS
    Type: Nature; 266; Mar. 31
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  • 68
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    Interplanetary baseline observations of type III solar radio bursts (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Simultaneous observations of type III radio bursts from spacecraft separated by 0.43 AU have been made using the solar orbiters Helios-A and Helios-B. The burst beginning at 19:22 UT on March 28, 1976, has been located from the intersection of the source directions measured at each spacecraft and from burst arrival-time differences. The source positions range from 0.03 AU from the sun at 3000 kHz to 0.08 AU at 585 kHz. The electron density along the burst trajectory and the exciter velocity (0.13c) were determined directly without the need to assume a density model, as has been done with single-spacecraft observations. The separation of Helios-A and -B has also provided measurements of burst directivity at low frequencies. For the March 28 burst the intensity observed from near the source longitude (Helios-B) was 3-10dB greater than that from 60 deg west of the source (Helios-A)
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 54; Oct. 197
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  • 69
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    Solar-generated quasi-biennial geomagnetic variation (1977)
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    Publication Date: 2011-08-17
    Description: The existence of highly correlated quasi-biennial variations in the geomagnetic field and in solar activity is demonstrated. The analysis uses a numerical filter technique applied to monthly averages of the geomagnetic horizontal component and of the Zurich relative sunspot number. Striking correlations are found between the quasi-biennial geomagnetic variations determined from several magnetic observatories located at widely different longitudes, indicating the worldwide nature of the obtained variation. The correlation coefficient between the filtered Dst index and the filtered relative sunspot number is found to be -0.79 at confidence level greater than 99% with a time lag of 4 months, solar activity preceding the Dst variation. The correlation between the unfiltered data of Dst and those of the sunspot number is also high with a similar time lag. Such a time lag has not been discussed in the literature, and a further study is required to establish the mode of sun-earth relationship that gives this time delay.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; Dec. 1
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  • 70
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    On the alignment of plasma anisotropies and the magnetic field direction in the solar wind (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: One year's Imp 6 solar wind plasma and magnetic field data are examined to determine whether anisotropies in particle velocity distributions are aligned with the measured interplanetary magnetic field vector. Alignment of components in the analysis plane was generally found to be excellent whenever plasma parameter magnitudes were larger than determination uncertainties, although some spread exists (typical rms approximately equal to 10 deg). By assuming cylindrical symmetry about the simultaneously measured magnetic field vector during the 1-year interval under study, three-dimensional values of selected solar wind plasma thermal parameters were constructed from the two-dimensional plasma measurements, and the statistical properties of their distributions have been tabulated.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 82; Dec. 1
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  • 71
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    Solar oscillations (1977)
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    Publication Date: 2011-08-17
    Description: The main observational results and related theoretical investigations concerning solar oscillations are reviewed. The normal modes of oscillation of the sun are classified according to their angular eigenvalues and the number of their radial nodes. Observations of excited normal modes are discussed, particularly in relation to five-minute oscillations, nonlinearly coupled unstable g-modes, oscillations of the sun's apparent diameter, and reported oscillations of the solar surface with a period of 2 hr 40 min. Linear stability calculations are briefly examined, and stochastic excitation of p-modes by turbulent convection is considered. The five-minute oscillations are described as the superposition of many excited nonradial p-modes.
    Keywords: SOLAR PHYSICS
    Type: Comments on Modern Physics; vol. 7
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  • 72
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    Investigation of coronal holes in the radio and far-ultraviolet ranges (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Results of coronal-hole observations carried out in the far-UV with a spectro-heliometer aboard Skylab are compared with corresponding results of ground-based radioheliograph measurements performed at frequencies of 80 and 160 MHz. It is found that the electron density derived from the far-UV observations for the transition region and lower corona is nearly three times greater than the value computed on the basis of the radio data. Unsuccessful attempts are made to eliminate this discrepancy by recalibrating the radio data and by recalculating the ionization equilibrium. A substantial local enhancement of the heavy-element abundance in certain parts of the transition region and inner chromosphere is considered as a possible cause of the discrepancy.
    Keywords: SOLAR PHYSICS
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  • 73
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    Helios-1 Faraday rotation experiment - Results and interpretations of the solar occultations in 1975 (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The first of two solar occultations of the satellite Helios-1 in 1975 occurred in April when the satellite's ray path approached the west limb of the sun to a minimum distance of 1.63 solar radii. The second occultation took place in late August/early September when Helios-1 was totally eclipsed by the photosphere. Measurements of the polarization angle of the linearly polarized telemetry signal were performed with automatic tracking polarimeters at the 64 m Goldstone Tracking Station in California and also at the 100 m radio telescope in Effelsberg, West Germany. The coronal Faraday rotation as a function of the solar offset for both occultations is shown in graphs. The theoretical significance of the observations is investigated.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysics - Zeitschrift fuer Geophysik; 42; 6, 19; 1977
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  • 74
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    Time delay occultation data of the Helios spacecrafts and preliminary analysis for probing the solar corona (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: S-band time delay measurements were collected from the spacecrafts Helios A and B during three solar occultations in 1975/76 within heliocentric distances of about 3 and 215 solar radii in terms of range, Doppler frequency shift, and electron content. A description is given concerning some characteristic features of the methods of measurement and data processing. 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 3 parameters of an average coronal electron density profile are derived in a preliminary analysis to yield electron densities of about 130 billion; 100 million; 7 million/cu m at r?3; 65; 215 solar radii. Transient phenomena are discussed and a velocity of propagation v approximately 900 km/s for plasma ejecta from a solar flare is determined from an extraordinary set of Helios B electron content measurements on April 30/May 1, 1976.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysics - Zeitschrift fuer Geophysik; 42; 6, 19; 1977
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  • 75
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    RMS electron density fluctuation at 1 AU (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Analytic expressions at 1 AU for the average RMS Electron Density Fluctuation and the ratio of RMS Electron Density Fluctuation to Electron Density, both as functions of the observational time scale, are constructed from average spacecraft in situ density measurements at approximately 1 AU and columnar phase fluctuation measurements over a wide variety of signal closet approach points. Additionally, the (one-dimensional) Electron Density Fluctuation spectrum and the Doppler phase fluctuation scale are derived, and various extrapolations to the region interior to 1 AU are made.
    Keywords: SOLAR PHYSICS
    Type: The Deep Space Network; p 135-140
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  • 76
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    The rotational spectrum of g-modes in the sun (1983)
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    Publication Date: 2011-08-18
    Description: Observations and calculations are presented which strongly suggest that the unique sequence of rotation rates due to g-modes is active in the sun. It is found that all angular harmonics from 1 = 2-11 appear to be resolved, while higher harmonics up to at least 1 = 20 also seem to be active. The extreme narrowness of many of the spectral lines indicates that the g-modes are locked in sets of constant 1 by a local mechanism which excites the modes and possibly regulates the long-term precision of their rotation. These sets act as a system of resonant, or nearly resonant, clocks which impose a degree of periodicity upon solar activity and measure the mean solar interior rotation
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 264
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  • 77
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    Observation of chromospheric evaporation during the Solar Maximum Mission (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A study is presented of the upward motions of part of the soft X-ray emitting plasma using data for flares collected in 1980 by the Bent Crystal Spectrometer and the Hard X-ray Burst Spectrometer on the Solar Maximum Mission satellite. Results show that upward motions of the soft X-ray plasma are temporally associated with the build up of the thermal phase of flares and with the period of energy deposition as indicated by the hard X-ray emission. In addition, it is found that the hardness of the hard X-ray spectrum, the evaporation velocity, and the rate of increase of the gradual phase are correlated. It is also possible that the total electron energy deposited in the chromosphere, the peak emission measure of the evaporating plasma, and the peak emission measure of the thermal coronal plasma may also be correlated.
    Keywords: SOLAR PHYSICS
    Type: (ISSN 0038-0938)
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  • 78
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    Conductive flux in the chromosphere derived from line linear polarization observation (1983)
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    Publication Date: 2011-08-18
    Description: It is shown that quantitative information on the mechanisms of energy transport which take place in solar flares can be obtained by measurement of impact line polarization. Linear polarization in two chromospheric lines (H-alpha and SI 1437 A) observed in the gradual phase of solar flares was investigated. The polarized electric vector is shown to be directed towards the center of the disk. The relationship between conductive heat flux and linear line polarization is determined using a function which represents the velocity distribution of electrons carrying heat flux. The relationship between linear polarization and heat flux is applied to the observed degree of polarization, which yields the conductive heat flux in the high chromosphere. It is determined that this conductive flux is of the order of magnitude of the total radiation loss in the chromosphere and below, which is also of the order of magnitude of the conductive flux in the transition zone.
    Keywords: SOLAR PHYSICS
    Type: (ISSN 0038-0938)
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  • 79
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    Radio blips and hard X-rays in solar flares (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The properties of short, narrow-band spikes occurring in groups at decimetric wavelengths have been extensively analyzed. The bursts, termed blips in the literature, have been found to appear in the impulsive phase of flares. They are associated with hard X-ray emission in 40 percent of all cases with simultaneous coverage. The correspondence between blips and X-ray spikes is generally not one-to-one, blips being more numerous than X-ray spikes. In some cases, however, close correlations between single events have been found. Blips have been discovered to drift in frequency and to decay in time similarly to type III bursts at lower frequency. They also resemble type III bursts in polarization. An analysis of starting frequencies, however, clearly shows that blips and type III bursts belong to different statistical populations. The narrow bandwidth of blips, the major qualitative difference with respect to type III bursts, suggests that blips are the signature of electron beams which either decay rapidly or have a locally enhanced emission due to the presence of some low-frequency wave. Blips have been shown to be an impulsive phase phenomenon occurring at densities of one to three billion per cu cm in the low corona.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 271; Aug. 1
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  • 80
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    Physical conditions in a quiescent prominence derived from UV spectra obtained with the UVSP instrument on the SMM (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A quiescent prominence observed above the north-west limb on November 20, 1980, is analyzed using data obtained with the UV spectrometer and polarimeter (UVSP) on the Solar Maximum Mission (SMM). The spectral data include the lines 1215 A of H1, 1401 A of OIV, 1402 A of SIIV, 1548 A of CIV, 1640 A of HeI, and 1655 A of CI. From an analysis of these lines and their emission patterns, the physical characteristics of the prominence plasma are deduced, and it is suggested that the prominence consisted of flux tubes at various temperatures. In the hotter parts of the plasma the number density reached values of about 3 x 10 to the 11th/cu cm.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 84; April 19
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  • 81
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    Vertical gradients of sunspot magnetic fields (1983)
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    Publication Date: 2011-08-18
    Description: The results of a Solar Maximum Mission (SMM) guest investigation to determine the vertical gradients of sunspot magnetic fields for the first time from coordinated observations of photospheric and transition-region fields are described. Descriptions are given of both the photospheric vector field of a sunspot, derived from observations using the NASA Marshall Space Flight Center vector magnetograph, and of the line-of-sight component in the transition region, obtained from the SMM Ultraviolet Spectrometer and Polarimeter instrument. On the basis of these data, vertical gradients of the line-of-sight magnetic field component are calculated using three methods. It is found that the vertical gradient of Bz is lower than values from previous studies and that the transition-region field occurs at a height of approximately 4000-6000 km above the photosphere.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 84; April 19
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  • 82
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    Dynamics and spectroscopy of asymmetrically heated coronal loops (1983)
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    Publication Date: 2011-08-18
    Description: Numerical models of steady flows along coronal magnetic flux tubes of varying cross sectional areas are investigated. The flows are induced by altering the spatial symmetry of the heating. In two cases the flux tube geometry is symmetric about the top of the loop, but the spatial dependence of the heating rate is changed from a symmetric deposition which supports a stationary equilibrium to a time-independent asymmetric deposition. In a third case the volumetric heating rate is uniform, but one half of the loop is larger in volume than the other. The resulting velocity structure varies significantly with changes in the flux tube geometry. Calculations of the ionization balance and line emission for a number of ionization stages of oxygen suggest that heating induced flows may be responsible for the redshifts seen in spectral lines formed in the network at transition region temperatures.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 267
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  • 83
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    Microwave signatures from a reconnecting plasma pinch, with application to loop flares (1983)
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    Publication Date: 2011-08-18
    Description: A calculation is made of microwave signature of a cylindrical plasma pinch undergoing magnetic reconnection, a process which occurs in many astrophysical situations, such as solar flares. Depending on the viewing angle and the average energy of the accelerated electrons, the microwaves from this betatron-like source show various amounts of circular polarization. The degree of polarization is shown to be frequency dependent, and the sense of polarization is sometimes reversed. The power spectrum is predicted to have several interesting properties, which can be compared with high-resolution measurements.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 275; 901-915
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  • 84
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    Effects of core perturbations on the structure of the sun (1983)
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    Publication Date: 2011-08-18
    Description: The effects of perturbing the inner part of the solar core where the hydrogen abundance has been partially depleted by nuclear burning are investigated. Small regions are mixed within the core and the evolution of the resulting luminosity and radius perturbations is followed. The sensitivity of the solar luminosity and radius to mixing events of different sizes and at different locations in the core is determined and several relationships between the luminosity and radius perturbations are examined to see if the value of one of these perturbations can be inferred from a measurement of the other. It is found that any core perturbation which alters the hydrostatic structures will immediately affect the solar luminosity and radius. The behavior of these perturbations depends on the location of the mixing event within the core. Mixing events cannot produce the decrease in the solar radius without leading to a homogeneous evolution of the solar core and/or to a prohibitively large change in the solar luminosity.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 273; 795-804
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  • 85
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    Si III line ratios in the sun (1983)
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    Publication Date: 2011-08-18
    Description: New atomic data for Si III have been used to predict level populations and emission-line intensity ratios for electron densities and temperatures appropriate to the solar transition region. The electron impact collision rates used here are substantially larger than those previously published owing to delineation of the complex resonance structures in the low-energy collision strengths. This together with small changes in the spontaneous radiative rates produces significant changes in the calculated intensity ratios. Generally good agreement is found with observations obtained using the Naval Research Laboratory slit spectrograph aboard Skylab, electron densities from three Si III ratios and from other methods normally agreeing to 0.2 dex or better for a wide variety of solar features. For a fourth ratio, incorporating lines with a wide wavelength separation, the agreement is less satisfactory, possibly owing to uncertainties in the observational data.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 274; 420-428
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  • 86
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    Lines of Fe XII sensitive to coronal electron density (1983)
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    Publication Date: 2011-08-18
    Description: Lines of Fe XII sensitive to coronal electron density are discussed. The lines appear in solar spectra obtained by the Naval Research Laboratory (NRL) slit spectograph flown on Skylab. These lines are due to transitions between levels of the 3s 2 3p 3 configuration and fall at the wavelengths 1242.03 A, 1349.38 A, 2169.03 A, 2405.71 A, and 2565.99 A. It is shown that the line at 2169.03 A is severely blended by a line of Ni II at heights less than 12 arcsec outside the solar limb. Above 12 arcsec the lines at 2169.03 and 2405.71 A are apparently unblended and can be used to derive electron densities. An average coronal electron pressure of 6 x 10 to the 14th/cu cm K is obtained. However, the emitting path lengths of the Fe XII lines, deduced using the electron densities and absolute intensities, are unrealistically large. The reason for this difficulty is unclear.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 273; 822-828
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  • 87
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    Determination of solar wind elemental abundances from M/Q observations during three periods in 1980 (1983)
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    Publication Date: 2011-08-18
    Description: Mass spectra in the M/Q range from 2 to 3, provided by a high-resolution mode of the ISEE-3 Plasma Composition Experiment, were evaluated for three selected periods during early 1980. The observed Ne/O ratios are compatible with estimated solar abundance ratios. In two of the three periods, the He/Ne-ratios agree with the Apollo foil results. Freezing-in temperatures for oxygen are similar to those obtained by other groups. Possible reasons for an unexpectedly high flux at M/Q = 2.4 are discussed.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 88; 359-376
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  • 88
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    Solar flare X-ray spectra from the P78-1 spacecraft (1983)
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    Publication Date: 2011-08-18
    Description: Results from the high resolution solar X-ray spectrometer experiments on the P78-1 spacecraft are discussed. These results concern physical quantities such as electron temperature and density, turbulence, mass motions, and state of ionization equilibrium, characteristic of the thermal soft X-ray emitting flare plasma, and the time behavior of these quantities during flares. In addition, a brief description of the instruments is given, the plasma diagnostics used in interpreting the spectra are summarized, and the origin of the thermal soft X-ray emitting plasma is discussed in light of the P78-1 results, earlier data, and numerical simulations of magnetic flux tubes heated to solar flare temperatures.
    Keywords: SOLAR PHYSICS
    Type: (ISSN 0038-0938)
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  • 89
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    Purely coronal flare-like variations (1983)
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    Publication Date: 2011-08-18
    Description: Quasiperiodic X-ray, UV, microwave, and metric-wave variations after a solar flare on November 6, 1980 are reported and analyzed, based on observational data from SMM (HXRBS, UVSP, HXIS), GOES-2, the 100-m radiotelescope at Bonn, and the Nancay radioheliograph. The maxima of the 13 brightenings observed are listed and characterized; a comparison is made with a 'normal' flare at 17:26 UT on the same day. The HXIS and UVSP data are discussed in terms of the physical properties, X-ray flux, O V flux, and H-alpha flux. The variations are found to be mainly thermal and purely coronal, with no chromospheric (H-alpha) participation (in contrast to the 17:26 flare). Since strong X-ray emissions were observed which should have involved the chromosphere through magnetic-field-line heat conduction, it is proposed that the variations wre produced ina coronal plasmoid magnetically separate from the chromosphere. A mechanism for the evolution of such a plasmoid from the upper loops of a giant X-ray arch is discussed. An iterative HXIS-image-deconvolution process is presented in an appendix.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 85; June 198
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  • 90
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    Expected intensities of solar forbidden lines emitted from 2p(k) (k = 2, 3, 4) configurations (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Predicted intensities of all significant transitions within the ground configurations of six-, seven-, and eight-electron ions are tabulated for solar conditions, on a common scale. Some applications of the table entries to line identification and emission measure analysis are presented, including proposed Mg VI classifications for the coronal lines 3488.5 A and 3502.5 A.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 85; May 1983
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  • 91
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    Heliospheric magnetic fields and plasmas (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A survey of the existing literature on heliospheric physics, covering the period 1972-1982, is presented. Attention is given to observations and theories germane to the examination of the heliosphere as a large-scale astrophysical system that is part of the earth's environment. The literature includes data and models for magnetic sectors and the large-scale magnetic field, the large-scale plasma structure, and models and observed variations in the solar wind. Consideration is also devoted to the transient and corotating streams and shocks, the composition of the solar wind, and to MHD turbulence, waves, and discontinuities. More intensive investigations of the region near 1 AU are recommended, particularly to characterize the coronal source of the solar wind. The solar polar mission will be the first to provide radial measurements for comparisons with previous exclusively ecliptic measurements of solar activities.
    Keywords: SOLAR PHYSICS
    Type: (ISSN 0034-6853)
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  • 92
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    Evidence for inhomogeneous thermal sources of two similar solar spike events of 1978 May 5 and December 4 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Two short duration single spike solar events of 1978 May 5 and December 4 exhibit similar time profiles in the microwave and hard X-ray ranges, indicating emission from compact sources. Microwave spectral observations exhibit inhomogeneities present in the source parameters. The existence of fine time structures in the microwave time profiles at 10.4 GHz from Berne are interpreted as a signature of the dynamics of a disturbance traveling through the source at the ion-sound speed. Stereoscopic observations with the hard X-ray detector on the solar orbiter, Helios-2, and the Berne microwave antenna do not indicate any time lag or differences in the time profiles during the impulsive phase. This is taken as evidence for the absence of directionality of emission making beam models unlikely for short duration single spike events. Previously announced in STAR as N83-13047
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 270; July 1
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  • 93
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    Fluid motions in the solar chromosphere-corona transition region. III - Active region flows from wide slit Dopplergrams (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Large-scale velocity patterns observed in C IV in active regions show close correspondence with photospheric magnetic field patterns. In a large majority of cases, magnetic neutral lines show blueshift on their sun center side and redshift on their limbward side. The large-scale flow is consistent with widespread loop structure having downflow in both legs of the loops. Studies of individual bright loops, confirm that the flow is downward in most cases. However, an important subset of loops show flow from one end of the loop to the other.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 269; June 15
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  • 94
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    Atomic calculations for the Fe XX X-ray lines (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The atomic data presented here and in Bhatia and Mason (1980) allow the calculation of theoretical intensity ratios for all the EUV, UV, and X-ray lines from Fe XX. Tabulations are presently given for the transitions between levels in the 2s2 2p3, 2s2 2p2 3s, and 2s2 2p2 3d configurations of Fe(19+), and electron collision strengths are calculated by means of the 'distorted wave' approximation. In addition to the theoretical X-ray line intensity ratios, new spectral line identifications from a solar flare are presented.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics Supplement Series (ISSN 0365-0138); 52; April 19
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  • 95
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    Atomic calculations for Ca XVII - UV and X-ray lines (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Doschek et al. (1977) have pointed out the importance of the Ca XVII UV lines as an electron density diagnostic. Energy levels, transition probabilities, and collision strengths, are presently obtained for the 2s2, 2s 2p, 2p2, 2s 3s, 2s 3p, and 2s 3d configurations of Ca XVII, and the theoretical intensity ratios for the UV and X-ray lines are compared with observed intensities in solar flare spectra. Inconsistencies are indicated in the analysis of UV data, and discrepancies between observed and theoretical intensity ratios indicate that further studies are required. New identifications are suggested in the X-ray wavelength region.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics Supplement Series (ISSN 0365-0138); 52; April 19
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  • 96
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    Conductive flux in flaring solar chromospheres deduced from the linear polarization observations (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 119; 2, Ma; Mar. 198
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  • 97
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    Models of the formation of the solar nebula (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Protostellar cloud collapse and solar nebula formation models indicate that the size of the nebula produced will be larger in terms of both gas centrifugal balance R(CF) and collapse time diffusion length R(V). From this, it can be deduced that low mass nebulas are produced if (R(V)/R(CF))-squared is much greater than unity, while nebulas result for values lower than approximately unity. The total angular momentum value distinguishes most current models of the solar nebula. Analytic expressions for the surface density, nebular mass flux and photospheric temperature distributions during the formation stage are presented for simple modes illustrating and general properties of growing protostellar disks.
    Keywords: SOLAR PHYSICS
    Type: Icarus; 53; Jan. 198
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  • 98
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    Multiple transonic solutions with a new class of shock transitions in steady isothermal solar and stellar winds (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: It is shown that a new class of shock transitions arises in the transonic solutions of the steady isothermal solar wind equations when momentum deposition and/or nonradial flow tube divergence give rise to multiple critical points in the flow. These shock transitions between critical solutions occur for a certain range of the parameters which characterize the momentum deposition function. The isothermal wind equations allow multiple transonic solutions in the presence of such shock transitions, yielding a continuous solution passing through an inner critical point and solutions involving a shock transition between critical solutions. It is determined that these multiple transonic solutions have the same flow speed at the base but different supersonic flow speeds at infinity. It is found that the nonradial flow tube divergence and momentum addition are equivalent, which gives rise to multiple critical points and hence to multiple transonic solutions with shock transitions. In addition, the physical relevance of these properties are examined for astrophysical systems such as the inner solar wind, flows in extragalactic jets, and accretion discs.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 88; Mar. 1
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  • 99
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    Facular influences on the apparent solar shape (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The problem of the influence of faculae on apparent solar shape is examined in light of general facular contrast models. The diagonal components of the oblateness signal from the faculae observed are calculated, and it is found that the faculae can contribute a signal whose time dependence is similar to that of the Dicke and Goldenberg (1967) oblateness signal, allowing an acceptable fit to the oblateness measurements for a facular contrast within the range of acceptable values.
    Keywords: SOLAR PHYSICS
    Type: Nature; 301; Jan. 13
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  • 100
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    Numerical simulations of loops heated to solar flare temperatures. I - Gasdynamics. II - X-ray and UV spectroscopy (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The NRL's Dynamic Flux Tube Model is used to numerically simulate the dynamic response of a coronal magnetic loop to an energy input of the order encountered in solar flares. The coronal plasma is heated by the deposition of flare energy at the top of the loop to more than 10 million K, yielding a conduction front that moves toward the chromosphere, where the plasma is heated by the large downward conductive flux and ablates upward to the coronal part of the loop at velocities of a few hundred km/sec. The conduction front simultaneously produces chromospheric ablation and compresses the material ahead of it. With the aid of compressional instabilities, the compressed plasma grows throughout the flare heating phase, presenting a possible source of the flare optical continuum emission which is correlated with soft X-ray radiation. The observational consequences of rapidly heated loop gas dynamic processes are discussed. In the second part of this presentation, the dynamical calculation results previously obtained are used to predict the spectral line intensities, profiles and wavelengths of several X-ray lines and the UV line of Fe XXI at 1354.1 A. Three different viewing orientations of the loop are considered.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 265
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