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  • Other Sources  (390)
  • SOLAR PHYSICS  (390)
  • 1985-1989  (390)
  • 1985  (390)
  • 1
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    Solar monochromatic images in magneto-sensitive spectral lines and maps of vector magnetic fields (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A new method which allows by use of the monochromatic images in some magneto-sensitive spectra line to derive both the magnetic field strength as well as the angle between magnetic field lines and line of sight for various places in solar active regions is described. In this way two dimensional maps of vector magnetic fields may be constructed. This method was applied to some observational material and reasonable results were obtained. In addition, a project for constructing the three dimensional maps of vector magnetic fields was worked out.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Meas. of Solar Vector Magnetic Fields; p 368-374
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  • 2
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    Contribution functions for Zeeman-split lines, and line formation in photospheric faculae (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The transfer of polarized light in an inhomogeneous stellar atmosphere, and the formation of magnetically sensitive spectral lines, are discussed. A new method for the solution of the transfer equations is proposed. The method gives a natural definition of the contribution functions for Stokes' parameters, i.e., functions describing the contributions from different parts along the line-of-sight (LOS). The formalism includes all magneto-optical effects, and allows for an arbitrary variation of magnetic field, velocity field, temperature, density, etc., along the LOS. The formation of FeI lambda 5250.2 in photospheric faculae is described. A potential-field model of a facular element is presented, and spectra profiles and contribution functions are computed for the Stokes parameters I, Q, and V.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Meas. of Solar Vector Magnetic Fields; p 322-334
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  • 3
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    Generation and transfer of polarized radiation in the solar atmosphere: Physical mechanisms and magnetic-field diagnostics (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The main physical mechanisms responsible for the generation and transfer of polarized radiation in the solar atmosphere can be classified in a suitable bidimensional diagram with an indicator of the magnetic field strength on its vertical axis and an indicator of the radiation field anisotropy on its horizontal axis. The various polarimetric observations performed on solar spectral lines are interpreted with different theoretical schemes according to their classification in the diagram and to the optical depths involved. These theoretical schemes, and the associated diagnostic tools for inferring the magnetic field vector from observations are reviewed. In particular, the role of magneto-optical effects in determining the direction of the observed linear polarization in active regions is discussed in some detail.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Meas. of Solar Vector Magnetic Fields; p 279-299
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  • 4
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    Theoretical approach to evolution of solar magnetic field (1985)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Theoretical approaches to the evolution of solar atmosphere magnetic field are briefly reviewed from the standpoint of the physical significance. A new direction of analysis based on the possible manners of generation of electric current is considered, and its physical implications are discussed.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Meas. of Solar Vector Magnetic Fields; p 78-85
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  • 5
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    The vector structure of active magnetic fields (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Observations are needed to show the form of the strains introduced into the fields above the surface of the Sun. The longitudinal component alone does not provide the basic information, so that it has been necessary in the past to use the filamentary structure observed in H sub alpha to supplement the longitudinal information. Vector measurements provide the additional essential information to determine the strains, with the filamentary structure available as a check for consistency. It is to be expected, then, that vector measurements will permit a direct mapping of the strains imposed on the magnetic fields of active regions. It will be interesting to study the relation of those strains to the emergence of magnetic flux, flares, eruptive prominences, etc. In particular we may hope to study the relaxation of the strains via the dynamical nonequilibrium.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Meas. of Solar Vector Magnetic Fields; p 7-16
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  • 6
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    Comparisons of simultaneous vector magnetograms (1985)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Simultaneous vector magnetograms were obtained with the different magnetographs of the Okayama Astrophysical Observatory and the Sayan Mountain Observatory in October 1983. The data obtained show a good correspondence in general. The comparison makes clear something on the measuring accuracy of each magnetograph. Good correspondence is shown in circular and linear polarizations, and, in and near sunspots, of the velocity field. The azimuth of the magnetic fields show good agreement.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Meas. of Solar Vector Magnetic Fields; p 399-402
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  • 7
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    Inferred flows of electric currents in solar active regions (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Techniques to identify sources of major current systems in active regions and their channels of flow are explored. Measured photospheric vector magnetic fields together with high resolution white light and H-alpha photographs provide the data base to derive the current systems in the photosphere and chromosphere of a solar active region. Simple mathematical constructions of active region fields and currents are used to interpret these data under the assumptions that the fields in the lower atmosphere (below 200 km) may not be force free but those in the chromosphere and higher are. The results obtained for the complex active region AR 2372 are: (1) Spots exhibiting significant spiral structure in the penumbral filaments were the source of vertical currents at the photospheric surface; (2) Magnetic neutral lines where the transverse magnetic field was strongly sheared were channels along which a strong current system flowed; (3) The inferred current systems produced a neutral sheet and oppositely-flowing currents in the area of the magnetic delta configuration that was the site of flaring.
    Keywords: SOLAR PHYSICS
    Type: Meas. of Solar Vector Magnetic Fields; p 379-398
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  • 8
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    The effect of line damping, magneto-optics and parasitic light on the derivation of sunspot vector magnetic fields (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The least square fitting of Stokes observations of sunspots using a Milne-Eddington-Unno model appears to lead, in many circumstances, to various inconsistencies such as anomalously large doppler widths and, hence, small magnetic fields which are significantly below those inferred solely from the Zeeman splitting in the intensity profile. It is found that the introduction of additional physics into the model such as the inclusion of damping wings and magneto-optic birefrigence significantly improves the fit to Stokes parameters. Model fits excluding the intensity profile, i.e., of both magnitude as well as spectral shape of the polarization parameters alone, suggest that parasitic light in the intensity profile may also be a source of inconsistencies. The consequences of the physical changes on the vector properties of the field derived from the Fe I lambda 6173 line for the 17 November 1975 spot as well as on the thermodynamic state are discussed. A Doppler width delta lambda (D) - 25mA is bound to be consistent with a low spot temperature and microturbulence, and a damping constant of a = 0.2.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Meas. of Solar Vector Magnetic Fields; p 341
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  • 9
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    Trends in measurement of solar vector magnetic fields using the Zeeman effect (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Trends in spectropolarimetry as applied to the problem of Zeeman effect measurement are discussed. The use of detector arrays to improve observing efficiency is obtained. Which required new polarization modulation schemes that match the time required to read detector arrays. Another significant trend is narrowband filters, to improve angular and temporal coverage, and to Fourier transform spectrometers, to improve spectral coverage and precision. Low-polarization designs and improved methods for compensating instrumental polarization were developed. A requirement for high angular resolution suggests using adaptive optical devices to subdue the effects of bad seeing. The ultimate strategy to beat the seeing is to loft the telescope above the atmosphere such as is planned with a 30-cm telescope in 1985 and a 1250-cm telescope in 1990.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Meas. of Solar Vector Magnetic Fields; p 109-120
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  • 10
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    Modeling solar magnetic structures (1985)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Some ideas in the theoretical study of force-free magnetic fields and magnetostatic fields, which are relevant to the effort of using magnetograph data as inputs to model the quasi-static, large-scale magnetic structures in the solar atmosphere are discussed. Basic physical principles will be emphasized. An attempt will be made to assess what we may learn, physically, from the models based on these ideas. There is prospect for learning useful physics and this ought to be an incentive for intensifying the efforts to improve vector magnetograph technology and to solve the basic radiative-transfer problems encountered in the interpretation of magnetograph raw data.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Meas. of Solar Vector Magnetic Fields; p 49-65
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  • 11
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    Evidence for submergencew of magnetic flux in a growing active region (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: In NOAA Active Region 2372 (April 1980), 4 x 10 to the 20th power maxwell of magnetic flux concentrated within a 30" circular area disappeared overnight. Vector magnetograms show that all components of the magnetic field weakened together. If the field had weakened through diffusion or fluid flow, 80% of the original flux would still have been detected by the magnetograph within a suitably enlarged area. In fact there was at least a threefold decrease in detected flux. Evidently, magnetic field was removed from the photosphere. Since the disappearing flux was located in a region of low magnetic shear and low activity, it is unlikely that the field dissipated through reconnection. The most likely possibility is that flux submerged. Observations suggest that even in the growth phase of active regions, submergence is a strong process comparable in magnitude to emergence.
    Keywords: SOLAR PHYSICS
    Type: Meas. of Solar Vector Magnetic Fields; p 437
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  • 12
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    Effect of polarized radiative transfer on the Hanle magnetic field determination in prominences: Analysis of hydrogen H alpha line observations at Pic-du-Midi (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The linear polarization of the Hydrogen H alpha line of prominences has been computed, taking into account the effect of a magnetic field (Hanle effect), of the radiative transfer in the prominence, and of the depolarization due to collisions with the surrounding electrons and protons. The corresponding formalisms are developed in a forthcoming series of papers. In this paper, the main features of the computation method are summarized. The results of computation have been used for interpretation in terms of magnetic field vector measurements from H alpha polarimetric observations in prominences performed at Pic-du-Midi coronagraph-polarimeter. Simultaneous observations in one optically thin line (He I D(3)) and one optically thick line (H alpha) give an opportunity for solving the ambiguity on the field vector determination.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Meas. of Solar Vector Magnetic Fields; p 335-340
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  • 13
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    Diagnostics of vector magnetic fields (1985)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: It is shown that the vector magnetic fields derived from observations with a filter magnetograph will be severely distorted if the spatially unresolved magnetic structure is not properly accounted for. Thus the apparent vector field will appear much more horizontal than it really is, but this distortion is strongly dependent on the area factor and the temperature line weakenings. As the available fluxtube models are not sufficiently well determined, it is not possible to correct the filter magnetograph observations for these effects in a reliable way, although a crude correction is of course much better than no correction at all. The solution to this diagnostic problem is to observe simultaneously in suitable combinations of spectral lines, and/or use Stokes line profiles recorded with very high spectral resolution. The diagnostic power of using a Fourier transform spectrometer for polarimetry is shown and some results from I and V spectra are illustrated. The line asymmetries caused by mass motions inside the fluxtubes adds an extra complication to the diagnostic problem, in particular as there are indications that the motions are nonstationary in nature. The temperature structure appears to be a function of fluxtube diameter, as a clear difference between plage and network fluxtubes was revealed. The divergence of the magnetic field with height plays an essential role in the explanation of the Stokes V asymmetries (in combination with the mass motions). A self consistent treatment of the subarcsec field geometry may be required to allow an accurate derivation of the spatially averaged vector magnetic field from spectrally resolved data.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Meas. of Solar Vector Magnetic Fields; p 263-278
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  • 14
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    The global structure of magnetic fields which support quiescent prominences (1985)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Magnetic fields in quiescent prominences were observed, but only recently has it become possible to measure the full magnetic field vector. The component of the field along the line of sight, B (parallel) can be uniquely determined, whereas for the component perpendicular to the line of sight B (perpendicular) and -B (perpendicular) are indistinguishable. An ambiguity remains in the actual magnetic field vector, in particular with respect to its orientation relative to the prominence axis. A sample of more than 100 prominences were studied. A more detailed analysis of 10 prominences are presented, and then set these prominence fields into relation to the underlying photospheric fields. It is found from statistical analysis of several hundred prominences that in 25% of the cases the field penetrates the prominence directly, whereas in 75% the field orientation in the prominence is reversed.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Meas. of Solar Vector Magnetic Fields; p 101-106
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  • 15
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    Dynamic models of flux tubes in the interpretation of polarization measurements (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Recent observations of Stokes parameter profiles indicate the presence of mass motions with large velocity gradients associated with small-scale magnetic elements. Dynamic models of flux tubes were used in order to interpret observations of unresolved elements. It is clear that the physical picture of the dynamic models will be quite different from the hydrostatic ones since there is a strong coupling between the magnetic and the velocity field. Polarization measurements have to be interpreted in terms of dynamic models. Two-D steady flow solutions in slender magnetic tubes have been worked out. It was found that the main properties of the intensity line profiles as well as the asymmetries of the V Stokes profiles can be explained best in terms of magnetic elements with moderate field strength.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Meas. of Solar Vector Magnetic Fields; p 300-305
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  • 16
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    The Hanle effect applied to magnetic field measurements (1985)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: The Hanle effect is the modification by a local magnetic field of the polarization due to coherent scattering in spectral lines. It results from the precession of a classical oscillator about the magnetic field direction. The sophisticated quantum-mechanical treatment, which is required to compute the polarization parameters of scattered light, was developed. The main features of the Hanle effect concerning magnetic field measurements are: (1) a good sensitivity within the approximate range 0.1 B gamma rho to 10 B gamma rho where B gamma rho is the field strength yielding a Larmor period equal to the radiative lifetime, (2) there is no Hanle effect for field vectors parallel to the excitating beam, (3) the Hanle effect refers essentially to the linear polarization in a spectral line, (4) various points in the line profile are affected in the same way by change of linear polarization so that polarization parameters can be measured on the integrated line profile.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Meas. of Solar Vector Magnetic Fields; p 121-140
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  • 17
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    On the formation of coronal cavities (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The formation of a coronal cavity and its relation to a quiescent prominence is studied theoretically. The stability of condensation modes of a plasma in the coronal streamer model (Steinolfson et al., 1982) is considered using a two-dimensional time-dependent ideal MHD numerical simulation. It is found that a plasma with beta = 0.5 is unstable but one with beta = 4 is stable because the density enhancement of the plasma trapped by the closed fields increases with the strength of the magnetic field. The means by which condensation modes can produce a coronal cavity and/or initiate the formation of a prominence (depending on the field configuration) are discussed. It is argued that prominence and cavity material is all supplied from the chromospheric level in the form of spicules.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 102; 1-2,; 165-176
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  • 18
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    Mass fluxes and magnetic structures in the chromosphere and the transition region - Canopies (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Preliminary results of applying a model of canopy-type magnetic lines to account for observed mass fluxes in the chromosphere and transiton region are presented. A set of center-to-limb data obtained in H-alpha and C IV, and to which the model is applied, is reported. The C IV line is assumed to form everywhere at the same height, and the H-alpha formation height is derived by assuming that the absorption coefficient is proportional to the local density. The density ratio between H-alpha and C IV levels is taken to be 100. From the results, it is concluded that the model accounts for the low ratio of radial velocities C IV/H-alpha at r = 0, the increase of H-alpha velocity near the limb, and the general center-to-limb behavior in both lines.
    Keywords: SOLAR PHYSICS
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  • 19
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    Magnetic canopies and models of the solar chromosphere (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Magnetic canopies are the topologies formed by magnetic field lines as they spread from compact, nearly vertical concentrations of flux in the low photosphere into the large-scale organization of the corona and heliosphere. Analytical techniques for inferring the base-heights of canopies from magnetographic data are reviewed together with observational evidence that much of the sun is covered by canopies which lie two or more pressure scale heights below the level which is traditionally inferred from thin flux tube models. Implications of these results for modeling the structure and energetics of the chromosphere are discussed, and it is argued that future models should be based upon both spectroscopic and polarimetric data. Recent improvements in magnetostatic model atmospheres are reviewed, and new observational data, including C IV Doppler-grams from the Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission, are considered. Directions for future research in MHD modeling of canopies, in simulating spectrographic and polarimetric data from such models, and in observational programs are discussed.
    Keywords: SOLAR PHYSICS
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  • 20
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    Working group on chromospheric fields - Canopies (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Although there are many points of uncertainty and controversy, the working group on chromospheric fields focussed its discussion on the concept of canopies; i.e., no one disagreed that a central issue relating to magnetic fields and chromospheric models is to learn how the photospheric field spreads with height. However, it quickly became apparent that in the time available, there was little prospect of building new unified models of magnetic field phenomena in the chromosphere beyond the scope of the formal presentations. Thus, the discussion was devoted to formulating questions which seemed both possible to address in future work and important for advancing understanding of the chromosphere. It began by discussing unresolved physical issues (almost everything) and then proceeded to consider means, both observational and synthetic, to address them.
    Keywords: SOLAR PHYSICS
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  • 21
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    Recent studies of magnetic canopies (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Two current studies are described which stem from Giovanelli's seminal studies of the spreading of chromospheric fields near active regions and active-region network. First, improved observational techniques are described for obtaining magnetograms in the Ca II 8542 A, Fe I 8688 A, and C I 9111 A lines which at least in principle allow for more accurate treatment of instrumental noise and allow better inference of field orientation. Second, a generalized response function is developed for calculating theoretical magnetograph signals from arbitrary line-of-sight variations of magnetic field, and initial applications to two-dimensional, potential-field models of network fields are described. Preliminary indications are that potential-field models can better explain the presence of low-lying, diffuse horizontal fields than can thin flux-tube models, but fail to predict a differential response between the different lines.
    Keywords: SOLAR PHYSICS
    Type: Australian Journal of Physics (ISSN 0004-9506); 38; 919-928
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  • 22
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    Solar hard X-ray bursts (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The major results from the Solar Maximum Mission (SMM) are presented as they relate to our understanding of the energy release and particle transportation processes that lead to the high-energy X-ray aspects of solar flares. Evidence is reviewed for a 152-158 day periodicity in various aspects of solar activity, including the rate of occurence of hard X-ray and gamma-ray flares. The statistical properties of over 7000 hard X-ray flares detected with the Hard X-Ray Burst Spectrometer are presented, including the spectrum of peak rates and the distribution of the photon number spectrum. A flare classification scheme introduced by Tanaka is used, and characteristics of the different types (types A, B, and C) are noted. A model based on the association of type C flares and coronal mass ejections is presented to explain many of the characteristics of these gradual flares.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 100; 465-490
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  • 23
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    Observations of low-degree P-mode oscillations in 1984 (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Analysis of Stanford differential velocity observations has been extended through the 1984 observing season. Excellent quality observations were obtained in 1984 on 38 days in a 49 day interval from June 20th through August 7th. The power spectrum of this data has been examined and improved frequency determinations have been made for p-modes of degree 2 through 5 and order 5 through 34. Of special interest are the modes of the lower orders, n ranging from 5 to 10, which have not been identified previously.
    Keywords: SOLAR PHYSICS
    Type: Contributions to Proceedings from the NATO Advanced Research Workshop on the Seismology of the Sun and the Distant Stars; p 11-18
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  • 24
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    The detection of global convective wave flows on the Sun (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Global convective flows in the solar convection zone have been predicted by theoretical interpretations of the global-scale ordering of magnetic fields and activity centers and by theoretical analyses of rotating convection zones. Direct evidence of these flows in the photosphere has not previously been found despite several long-term efforts. The signatures of such flows have now been detected by analyzing the daily series of low-resolution Dopplergrams obtained at the Wilcox Solar Observatory at Stanford University. The signatures are patterns of alternating east and west flows with amplitudes on the order of 25 m/s and longitudinal extent of about 30 degrees. The patterns move across the disc at approximately the solar rotation rate and have lifetimes of at least several rotations. Boundaries of the fast and slow flows are often associated with large magnetic active regions.
    Keywords: SOLAR PHYSICS
    Type: Contributions to Proceedings from the NATO Advanced Research Workshop on the Seismology of the Sun and the Distant Stars; p 1-10
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  • 25
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    Coulomb collisions in the solar wind (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A major improvement of the present investigation over previous studies of the subject is related to the use of helium temperatures obtained from helium ion measurements uncontaminated by the high-velocity tail of the proton distribution. More observations, covering a large parameter range, were employed, and the effects of interspecies drift were taken into account. It is shown in a more definite way than has been done previously, that Coulomb collisions provide the most important mechanism bringing about equilibrium between helium and protons in the solar wind. Other mechanisms may play some part in restricted regions, but Coulomb collisions are dominant on the macroscale.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 7389-739
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  • 26
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    Stream dynamics between 1 AU and 2 AU - A comparison of observations and theory (1985)
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    Publication Date: 2011-08-19
    Description: A radial alignment of three solar wind stream structures observed by IMP-7 and -8 (at 1.0 AU) and Voyager 1 and 2 (in the range 1.4 to 1.8 AU) in late 1977 is presented. It is demonstrated that several important aspects of the observed dynamical evolution can be both qualitatively and quantitatively described with a single-fluid 2-D MHD numerical model of quasi-steady corotating flow, including accurate prediction of: (1) the formation of a corotating shock pair at 1.75 AU in the case of a simple, quasi-steady stream; (2) the coalescence of the thermodynamic and magnetic structures associated with the compression regions of two neighboring, interacting, corotating streams; and (3) the dynamical destruction of a small (i.e., low velocity-amplitude, short spatial-scale) stream by its overtaking of a slower moving, high-density region associated with a preceding transient flow. The evolution of these flow systems is discussed in terms of the concepts of filtering and entrainment.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 7377-738
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  • 27
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    Speed of sound in the solar interior (1985)
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    Publication Date: 2011-08-19
    Description: The sound speed of the solar interior is directly determinable on the basis of the frequencies of solar 5-min oscillations, irrespective of solar model, and relying only on a simple asymptotic description of the oscillations in terms of trapped acoustic waves. It is plausible that, by using this asymptotic determination as an initial trial in a more accurate inversion, and imposing constraints of smoothness on the solution resulting from the iteration, a good model representing the large scale structure of the sun which satisfies the observed frequencies may be determined.
    Keywords: SOLAR PHYSICS
    Type: Nature (ISSN 0028-0836); 315; 378-382
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  • 28
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    Radiative and reconnection instabilities - Compressible and viscous effects (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Filaments and flares are prominent indicators of the magnetic fields of solar activity. These instability phenomena arise from the influence of weak transport effects (radiation and resistivity, respectively) on coronal magnetodynamics and energy flow. It has been shown that the filament and flare (tearing or reconnection) mechanisms are resistively coupled in sheared magnetic fields of the kind existing in active regions. The present paper expands this treatment to include the effects of compressibility and viscosity, which are most prominent at short wavelengths. The results show that compressibility affects the radiative mode, including a modest increase of its growth rate, and that viscosity modifies the tearing mode, partially through a decrease of its growth rate. A comprehensive discussion of the mode structures and flows is presented. The strongest effect found is a reversal, at very long wavelengths, of the radiative cooling of the resistive interior layer of the tearing mode, caused by compressional heating.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 95; 119-140
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    Propagation of energetic electron streams in solar flares (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The microscopic stability of an electron stream flowing down to the photosphere from the corona is examined. It is found that, while a power-law distribution is stable in the low-density corona, it is unstable against the generation of magnetized electron plasma waves in the high-density photosphere. The scattering of these energetic electrons may alter their radiation signatures.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 95; 181-188
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    Nuclear processes and neutrino production in solar flares (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The determination of flare neutrino flux is approached from the standpoint of recent observations and theoretical results on the nuclear processes in solar flares. Attention is given to the energy spectra and total numbers of accelerated particles in flares, as well as their resulting production of beta(+)-emitting radionuclei and pions; these should be the primary sources of neutrinos. The observed 0.511 MeV line flux for the June 21, 1980 flare is compared with the expected from the number and spectrum of accelerated particles.
    Keywords: SOLAR PHYSICS
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    The physics of thermal instability in two dimensions (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Previous studies of a thermal (radiative) instability in a sheared magnetic field have shown that, under solar coronal conditions, cool condensations can form in a small neighborhood about the shear layer. Such results have served to model the formation of solar filaments (or prominences) observed to occur above photospheric magnetic polarity-inversion lines. A surprising conclusion of these studies is that the width of the condensation does not depend on the thermal conductivity. By examining the mass-flow patterns of two-dimensional condensations in the absence of thermal conduction, it is demonstrated that local plasma dynamics and the constraints imposed by boundary conditions are together sufficient to explain the size of the condensation width. In addition the results of a series of numerical calculations are presented which illustrate the characteristic mode structure of sheared-field condensations.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 97; 283-307
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    Bremsstrahlung spectra from thick-target electron beams with noncollisional energy losses (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A generalization of the Brown's (1971) formulation of the relationship between bremsstrahlung spectrum and mean electron spectrum (electrons in the range 10-100 keV) is presented with an objective of demonstrating the information content of bremsstrahlung spectra from a thick target. It is shown that the observed photon spectrum can be inverted to yield an integral functional of the electron spectrum and the effective energy loss rate. Furthermore, if observational or theoretical electron injection spectrum is known, an effective 'phenomenological' energy loss function can be obtained.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 292; L31-L34
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    High-resolution X-ray spectra of solar flares. VII - A long-duration X-ray flare associated with a coronal mass ejection (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It has been recognized that very long duration X-ray events (lasting several hours) are frequently associated with coronal mass ejection. Thus, Sheeley et al. (1983) found that the probability of the occurrence of a coronal mass ejection (CME) increases monotonically with the X-ray event duration time. It is pointed out that the association of long-duration, or long-decay, X-ray events (LDEs) with CMEs was first recognized from analysis of solar images obtained by the X-ray telescopes on Skylab and the Naval Research Laboratory (NRL) slitless spectroheliograph. Recently high-resolution Bragg crystal X-ray spectrometers have been flown on three spacecraft, including the Department of Defense P78-1 spacecraft, the NASA Solar Maximum Mission (SMM), and the Japanese Hinotori spacecraft. In the present paper, P78-1 X-ray spectra of an LDE which had its origin behind the solar west limb on November 14, 1980 is presented. The obtained data make it possible to estimate temperatures of the hottest portion of the magnetic loops in which the emission arises.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 292; 309-318
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    Persistence of shocks to large distances in the solar wind (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Present hydrodynamic models of solar wind streams predict that interactions will cause interplanetary shocks to decay and large-scale structures to coalesce and smooth out, with a decay length of 10-15 AU for moderate or small-amplitude shocks. The Pioneer 10 plasma data, extending 1-30 AU, are examined in the light of such predictions. It is found that coalescence of streams into a single stream per solar rotation does occur, in general, but that considerable structure remains by 30 AU. The leading edge of a stream often exhibits a velocity jump of greater than 20 km/s; many of these may be shocks. There is a characteristic velocity-density-temperature signature of these distant streams which differs from the close-in double-shock signature. A unique transient was seen in July 1982, at 28 AU, with a velocity jump of about 235 km/s.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 3967-397
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    Magnetic shear. II - Hale region 17244 (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A B-gamma(delta) sunspot group with growing delta-spots of trailing polarity shows evidence in H-alpha filament structure of a transition from a state of weak magnetic shear to a state of strong shear. The shear develops in the chromosphere and transition region to the corona overlying the photospheric magnetic neutral line separating the delta-spots from the leading polarity at a time when the delta-spots are undergoing rapid growth. Several major flares occur along the sheared portion of the neutral line following the shear development. Other segments of the neutral line far removed from the delta-spots show similar evidence of shear in the H-alpha filament structure and in C IV velocity patterns as well. These 'quiescent' regions of shear are relatively steady or decaying with time and show very little related activity.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 291; 344-355
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    A leaky magnetohydrodynamic waveguide model for the acceleration of high-speed solar wind streams in coronal holes (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It is now reasonably well established that there is a correlation between high-speed solar wind streams and coronal holes. It has been concluded that a significant addition of momentum and/or energy in the region of supersonic flow is needed to explain the observed particle flux and flow speed observed in the high-speed streams. The most likely source of this additional momentum appears to be magnetohydrodynamic (MHD) waves propagating up from the solar surface. The present investigation is concerned with the propagation of MHD waves in a structure of finite transverse size, taking into account the consequences for the acceleration of high-speed solar wind streams. A waveguide solution for a model coronal hole is described, giving attention to a geometric or ray analysis of the slab waveguide, a wave mode analysis, an analytic solution of the dispersion relation for high-frequency waves, and the calculation of the time-averaged wave force.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 291; 328-338
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    Changes of solar luminosity and radius following secular perturbations in the convective envelope (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The effect on solar models of several types of slow, spherically symmetric perturbations, acting at various depths within the convective envelope, are calculated. Results are presented on perturbations of the efficiency of convective energy transport (alpha perturbations) and on changes in the nongas component of pressure (beta perturbations). The effects of magnetic fields concentrated near the interface between the radiative core and the convective envelope are explored. It is found that the response and relaxation diagnostics depend both on the type of perturbation and on the depth at which the perturbation is applied. In addition to the general depth dependence, model behavior is sensitive to the presence of major ionization zones near the perturbed layer. The time dependence of the solar model behavior is characterized by an initial hydrostatic reaction followed by a thermal readjustment on a time scale of about 100 years, and finally relaxation to a new thermal equilibrium on a Kelvin time scale.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 290; 748-757
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    New identifications of Fe XVII spectral lines in solar flares (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The identifications of Fe XVII transitions between the 2s(2)2p(5)3s, 3p, and 3d configurations published by Jupen (1984) are reviewed. The review is based on examining spectroheliograms of solar flares obtained by a Naval Research Laboratory instrument on Skylab (S082-A). Agreement is obtained with the majority of identifications given by Jupen, but different wavelengths are found for a few of the lines. The relative intensities of the lines are qualitatively in agreement with calculations. A broad line at 1153.20 A is identified with the 2p(5)3s(3)P(0)-2p(5)3s(3)P1 forbidden transition of Fe XVII. This line was found in flare spectra obtained by the NRL slit spectrograph on Skylab (S082-B).
    Keywords: SOLAR PHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 212; 41P-45P
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    Solar burst with millimetre-wave emission at high frequency only (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The first high sensitivity and high time-resolution observations of a solar burst taken simultaneously at 90 GHz and at 30 GHz are presented. These identify a unique impulsive burst on May 21, 1984 with fast pulsed emission that was considerably more intense at 90 GHz than at lower frequencies. Hard X-ray time structures at energies above 25 keV were almost identical to the 90 GHz structures to better than 1 s. The structure of the onset of the major 90 GHz burst coincided with the hard X-ray structure to within 128 ms. All 90 GHz major time structures consisted of trains of multiple subsecond pulses with rise times as short as 0.03 s and amplitudes that were large compared with the mean flux. When detectable, the 30 GHz subsecond pulses had smaller relative amplitude and were in phase with the corresponding 90 GHz pulses.
    Keywords: SOLAR PHYSICS
    Type: Nature (ISSN 0028-0836); 313; 380-382
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  • 40
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    Microwave and X-ray observations of delayed brightenings at sites remote from the primary flare locations (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Five examples of solar flares observed with the 17-GHz interferometer at Nobeyama in which a secondary microwave burst occurred at a distance of 100,000 km to 1,000,000 km from the primary flare site are presented. The secondary microwave burst in all five cases had a similar time profile to the primary burst with a delay of 2 to 25 s. The velocity of a triggering agent inferred from this delay and spatial separation is 10,000 km to 100,000 km/s. The intensity of the secondary burst was a factor of 3 to 25 smaller than that of the primary burst in all events except for one case in which it was a factor of 2 larger. The polarization degree of the secondary burst at 17 GHz was 35 percent, significantly higher than the average value for typical impulsive bursts. Two of the events were accompanied by meterwave type III/V bursts located high in the corona between the primary and secondary sites. For two of the other events, X-ray images of the secondary source were obtained with the hard-X-ray imaging spectrometer on the Solar Maximum Mission. These observations strongly suggest that the distant microwave bursts were produced by electrons with energies of 10 keV to 100 keV which were channeled along a huge loop from the main flare site to the remote location.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 288; 806-819
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    The modelling of latitudinal gradients in the solar wind in the outer solar system (1985)
    In:  Other Sources
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    Publication Date: 2016-06-07
    Description: A steady, axisymmetric, quasi-radial, global model is developed for thermally driven stellar winds with embedded magnetic fields. The asymptotic, linear results are presented for 0(1) latitudinal variations in the radial magnetic field, mass-loss rate, and radial velocity of the wind. The MHD equations are solved for the latitudinal dependence of the rotational velocity and magnetic field. They are driven by the meridional flows that develop naturally from internal magnetic stresses. Most flows open flux tubes in the stars equatorial plane, redistributing mass and magnetic flux as a function of stellar latitude. The plasma spins up to conserve angular momentum in fields and plasma.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ. Res. Rept.: 1984 NASA/ASEE Summer Faculty Fellowship Program (NASA-CR; 22p
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    Overheated Open Coronal Regions (1985)
    In:  CASI
    Details
    Publication Date: 2014-09-16
    Description: The physics of compact, hydrostatic coronal shells formed from the collapse of overheated coronae is addressed. A large number of hydrostatic shells was computed for the usual exponential heating law with constant damping length. The boundary conditions were that on both sides of a shell the conductive flux at chromospheric temperatures is small. The boundary value problem was solved with a shooting technique. The main goal of the calculations was to determine the dependence of the shells on coronal heating flux (F sub Mo) and damping length (L); and in particular, to localize the boundary line in the parameter space (F sub Mo, L) that separates normal extended coronae from coronal shells.
    Keywords: SOLAR PHYSICS
    Type: NASA. Goddard Space Flight Center The Origin of Nonradiative Heating(Momentum in Hot Stars; p 125-129
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    Heating in the Solar Mantle (1985)
    In:  CASI
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    Publication Date: 2014-09-16
    Description: In the case of the solar chromosphere and corona (the solar mantle) the primary energy source is the mechanical energy from photospheric motions. Plenty of energy is available; the problem is to transfer the needed amount of energy to the proper place to account for the observations. The global problem is reviewed from the point of view of the generation and transmission of energy, the intermediate storage of energy, and the release of energy in such a way that the observed features are generated.
    Keywords: SOLAR PHYSICS
    Type: NASA. Goddard Space Flight Center The Origin of Nonradiative Heating(Momentum in Hot Stars; p 101-105
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    The Effects of Seeing on Noise (1985)
    In:  CASI
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    Publication Date: 2014-08-21
    Description: The effect of the supergranulation velocity field combined with seeing smearing of the solar image on the measurement of solar oscillations is discussed. Depending on the nature of the observational velocity determination scheme, the image motions can shift the background velocity pattern and produce a source of noise that reduces the quality of the observations. The magnitude of this effect is estimated and observational results which are consistent with this estimate are presented.
    Keywords: SOLAR PHYSICS
    Type: Solar Seismology from Space.; p 263-270
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    Broadening of looplike solar coronal transients (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The broadening of the tops of nine outwardly expanding looplike coronal mass-ejection transients observed during 1973-1974 and 1980 has been examined. Five of the nine transients exhibit increased breadth with time (height); although the rates vary widely, no event shows an increase which can be fitted by a power-law form with a greater-than-linear increase with height. The breadth of four events decreases with height. When all nine events are considered together, the transient breadth with height is fitted with an expression h varies as R exp 0.48 with large scatter. In addition, measurements of the total observed loop length of the nine transients show that this length L varies as R exp 1.30. Both of these results are contrary to the predictions of one model of loop expulsion as a result of an assumed azimuthal magnetic field gradient. Finally, when combined with the facts that looplike mass ejections are usually associated with the occurrence of eruptive prominences, and that such mass ejections are generally accelerated through the corona, it is found that the observed variation of transient breadth with height contradicts some characteristics of self-similar fluid flow which have been ascribed to mass-ejection transients.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 299; 526-535
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  • 46
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    Quantitative analysis of hard X-ray 'footpoint' flares observed by the solar maximum mission (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Amplifier gain and collimator hole size variations across the field of view, amplifier/filter efficiency, variations in effective collimator hole size and angular response with photon energy, dead-time, and hard X-ray plate transmission, are among the factors for which instrumental corrections have to be incorporated to effect reliable correction and deconvolution of images from the SMM satellite's Hard X-ray Imaging Spectrometer (HXIS). Attention is given to the substantial Poisson noise in these energy bands. The maximum entropy deconvolution/correction routine developed for establishing the spatial structure reliably inferrable from HXIS data is presented, together with the results of the application of this routine to the three impulsive flares reported by Duijemian et al. (1982) from April 10, May 21, and November 5, 1980.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 99; 231-262
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    Multiwavelength analysis of a well observed flare from SMM (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Observations of an M 1.4 flare which began at 17:00 UT on November 12, 1980, are presented and analyzed. Ground based H-alpha and magnetogram data have been combined with EUV, soft and hard X-ray observations made with instruments on-board the Solar Maximum Mission satellite. The preflare phase was marked by a gradual brightening of the flare site in O v and the disappearance of an H-alpha filament. Filament ejecta were seen in O v moving southward at a speed of about 60 km/s, before the impulsive phase. The flare loop footpoints brightened in H-alpha and the Ca XIX resonance line broadened dramatically 2 min before the impulsive phase. Nonthermal hard X-ray emission was detected from the loop footpoints during the impulsive phase, while during the same period blue-shifts corresponding to upflows of 200-250 km/s were seen in Ca XIX. Evidence was found for energy deposition in both the chromosphere and corona at a number of stages during the flare. Two widely studied mechanisms for the production of the high temperature soft X-ray flare plasma in the corona are considered, i.e. chromospheric evaporation, and a model in which the heating and transfer of material occurs between flux tubes during reconnection.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 99; 167-188
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    White-light and radio sounding observations of coronal transients (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A concerted search for coronal transients was conducted with the 'Solwind' coronagraph during the solar occultations of the two Helios spacecraft in October/November 1979. The polarization angle and bandwidth of the linearly polarized S-band downlink signal were monitored at the three 64-m tracking stations of the NASA Deep Space Network to determine coronal Faraday rotation and spectral broadening. A one-to-one correspondence could be established between abrupt disturbances in the two signal parameters and the passage of a white-light transient through the signal ray path from spacecraft to earth. The white-light morphology and the additional information provided by the radio sounding coverage are presented for each of the five distinct events recorded. Although no specific example could be observed in sufficient detail in both white light and Faraday rotation to derive the small-scale magnetic structure, some qualitative descriptions of the orientation and rough estimates of the magnitude of the transient magnetic field could be made.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 98; 341-368
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    Dynamics of solar filaments. IV - Structure and mass flow of an active region filament (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An active region filament near the center of the solar disk was observed on September 29-30, 1980, with the Multichannel Subtractive Double Pass Spectrograph of the Meudon solar tower and the UV Spectrograph and Polarimeter aboard the SMM satellite. H-alpha and C IV measurements are presently used to study brightness and material velocity in the 10,000 and 100,000 K temperature ranges, and photospheric magnetograms are used to investigate the underlying magnetic field. Attention is given to the constraints imposed on possible filament structures by observations, as well as the expected MHD relationships.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 153; 1, De
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    Temporal behaviour of the thermal model of hard X-ray bursts (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A simple, analytic model is presented of a hot, thermal hard X-ray source, continuously heated, bounded by ion-acoustic conduction fronts, and expanding in a loop. The model is used to investigate the assumption that the 'rise time' of the X-ray emission is approximately given by the loop length divided by the ion-sound speed appropriate to the peak temperature. It is found that a freely-expanding source does not behave in this way; instead, the rise time is symptomatic of the timescale for primary energy release. If the energy release rate does not fall significantly before the source fills the loop, however, then this assumption may be approximately satisfied, if a condition on the temporal behavior of the energy release is satisfied. Finally, some remarks on the relative timing of temperature and emission measure peaks are made, and possible further applications mentioned of the results presented herein.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 98; 293-304
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    Fundamental and harmonic emission in interplanetary type II radio bursts (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Three interplanetary type II radio bursts which show two prominent and long duration bands in their dynamic spectra were analyzed in detail and compared to similar bands in meter wavelength type II events. These bands, which differ by a factor of about two in frequency, were interpreted in terms of fundamental and harmonic emission. The fundamental component has a greater average intensity than the harmonic, due largely to short intense brightenings. The fundamental spectral profile is more narrow than that of the harmonic, with harmonic band typically exhibiting a larger bandwidth to frequency ratio than the fundamental by a factor of two. The fundamental has a larger source size than the harmonic, 160 degrees versus 110 degrees, on average, as viewed from the sun. Two of the events have source positions which correlate well with the associated flare positions.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 151; 2, Oc; 215-221
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    Sunspots (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It is pointed out that the sun provides a close-up view of many astrophysically important phenomena, nearly all connected with the causes and effects of solar magnetic fields. The present article provides a review of the role of sunspots in a number of new areas of research. Connections with other solar phenomena are examined, taking into account flares, the solar magnetic cycle, global flows, luminosity variation, and global oscillations. A selective review of the structure and dynamic phenomena observed within sunspots is also presented. It is found that sunspots are usually contorted during the growth phase of an active region as magnetic field rapidly emerges and sunspots form, coalesce, and move past or even through each other. Attention is given to structure and flows, oscillations and waves, and plans for future studies.
    Keywords: SOLAR PHYSICS
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    Great microwave bursts and hard X-rays from solar flares (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In the present study of the microwave and hard X-ray characteristics of 13 solar flares emitting microwave fluxes greater than 500 solar flux units, simultaneous 3-35 GHz and hard X-ray observations were conducted in the 30-500 keV energy range. An analysis is conducted to determine whether the same distribution of energetic electrons can explain both emissions; tests for any correlations between them yield results suggesting that optically thick microwave emission, near the peak frequency, originates in the same electron population that produces the hard X-rays. A single temperature model and a multitemperature model were tested for consistency with the coincident X-ray and microwave spectra at microwave burst maximum; neither model, however, attempts to explain the high frequency component of the microwave spectrum.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 96; 339-356
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    Observations of steady anomalous magnetic heating in thin current sheets (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The Hard X-ray Imaging Spectrometer of the Solar Maximum Mission has yielded observations of a faint, steadily emitting loop-like structure, which have allowed the thermal evolution of this loop over a period of about 15 hr to be followed. Only 0.1 percent of the volume of the loop appears to be steadily heated, at the large rate of 0.6 erg/cu cm sec; this suggests that the heating represents the dissipation of magnetic fields in thin current sheets. Ion-kinetic tearing, as proposed by Galeev et al. (1981), is noted to be especially consonant with these observations. The source of the present X-ray emission is identified with the H-alpha filament in the same region. The present findings are held to constitute the first direct evidence for the steady dissipation of coronal magnetic fields via enhanced thin current sheet resistivity.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 96; 253-275
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    Alignment of velocity and field changes across tangential discontinuities in the solar wind (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Three-dimensional IMP 8 and Voyager 2 plasma and field data are used to investigate the relative changes in direction of the velocity and magnetic field vectors across tangential discontinuities in the solar wind. It is found that Delta-v and Delta-B/rho exp 1/2 are closely aligned either parallel or antiparallel to each other in the sense associated with the propagation of Alfven waves or rotational discontinuities outward from the sun. This alignment is observed at all solar distances betwen 1 and 2.2 AU and is independent of the solar wind stream structure. Several possible causes of the effect are briefly discussed, including interplanetary turbulence, the propagation of large-amplitude Alfvenic fluctuations traveling independently through the solar wind on both sides of the discontinuities, and the propagation of surface waves on tangential discontinuities.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 6627-663
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    Temporal characteristics of the solar UV flux and He I line at 1083 nm (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It is pointed out that the solar UV flux in the 170- to 210-nm range is important because it photodissociates O2 in the terrestrial atmosphere and thereby initiates the production of ozone and other odd-oxygen chemistry in the stratosphere. The 210- to 290-nm solar UV flux heats the stratosphere. There is consequently a great interest in the temporal variations of the solar UV flux and its relation to ground-based measures of solar activity which may be useful in estimating the UV flux variations. The present investigation is concerned with daily values of 205-nm solar UV flux data measured with the aid of the Nimbus 7 satellite during the period from November 1978 to November 1982, taking into account also measurements of the equivalent width of the He I solar absorption line at 1083 at the National Solar Observatory. Attention is given to an analysis of the data, episodes of activity, and long-term variations.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 6267-627
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  • 57
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    Coronal heating by resonant (A.C.) and nonresonant (D.C.) mechanisms (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The solar coronal heating studies of Ionson (1984) and Heyvaerts and Priest (1984) invoke categorically different mechanisms involving the generation of ac currents, in the case of resonant mechanisms, and dc currents, in the case of nonresonant ones. Attention is presently given to Heyvaerts and Priest's finding that dc heating mechanisms are represented by the m = 0 harmonic of Ionson's unified theory of coronal heating, which is here extended to include all excitation harmonics, including m = 0. The efficiency of dc mechanisms is severely limited by the constraint that the dissipation time be comparable to the correlation time of the convective driver and smaller than the magnetic flux leakage time, suggesting for the solar case that dc processes dominate heating in young, active region loops, while ac ones dominate heating in both active region and large scale loops.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 146; 2, Ma
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  • 58
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    Initial phase of chromospheric evaporation in a solar flare (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Attention is given to the initial phase of chromospheric evaporation in the solar flare observed by the Solar Maximum Mission's Hard X-ray Imaging Spectrometer, on May 21, 1980. Images of the flaring region in the 3.5-8.0 and 16-30 keV energy bands indicate that both the soft and hard X-ray emissions are localized near the footpoints early in the event, while they are weaker from the rest of the flaring loop system; this implies that there is no heating taking place at the top of the loops, while energy is primarily deposited at their base. Observations of the energy deposition in the chromosphere by electrons accelerated in the flare region to energies above 25 keV furnish further support for an interpretation of plasma upflows as the mechanism responsible for the formation of the soft X-ray flare, identified with chromospheric evaporation.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 96; 129-142
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  • 59
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    Evidence for systematic flows in the transition region around prominences (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The solar transition region in the neighborhood of prominences has been studied from observations with the Ultraviolet Spectrometer and Polarimeter of NASA's Solar Maximum Mission satellite. Dopplergrams from observations of the transition-region lines C IV 1548 A and Si IV 1393 A, which are formed at about 100,000 K, give velocity amplitudes typically in the range + or - 15 km/s. Prominences are found to be located very close to dividing lines between areas of up- and down-drafts in the transition-region. The observed pattern suggests that the 100,000 K gas flows take place within arcades of magnetic loops, which most likely are part of the supporting magnetic structure for the prominence matter. An additional band of blue-ward Doppler shifts is frequently seen close to quiescent prominences. This may be the source of outward flowing matter along the helmet streamers above filament channels.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 96; 35-51
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  • 60
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    Expected intensities of solar neon-like ions (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A study of the expected intensities of the stronger solar neon-like ion emission lines, some not yet observed, is carried out to compare with the observational situation. The potential usefulness of the 2p5 3s(3P2) - 2p6 forbidden line as a density diagnostic is discussed, and new electric quadrupole lines in the soft X-ray range are noted. 'Observability diagrams' are presented as a convenient overview of the known and unobserved lines. The S VII resonance lines appear to have anomalous intensities.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 96; 11-26
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  • 61
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    Population mechanisms for the He(+) n = 3 levels determined from measurements of the solar 1640 A emission (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The 1640 A line profile is analyzed using solar data obtained by the NRL slit spectrograph on Skylab. Data from coronal hole regions, quiet sun regions, active regions, prominence regions, and flare regions are presented. The relative densities of 3s, 3p, and 3d levels are determined from the data, and the dominant population mechanisms for these levels are inferred using a rate equation model for the He(+) ion. The relative importance of collisional excitation, radiative recombination, and photoexcitation is determined for each of the solar regions.
    Keywords: SOLAR PHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 213; 417-434
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  • 62
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    The evolution of interplanetary shocks (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Unambiguous identification of the solar events associated with 48 interplanetary (IP) shocks has been facilitated by the observation of radio emission generated by the shocks. This identification makes possible an investigation of the way in which these shocks evolve and of the relationship between solar event 'strength' and shock velocity. All but two of the 48 solar events associated with IP type II radio emission included long-duration soft X-ray events (LDE's). In addition, it is shown that all intense LDE's are associated with IP shocks. A weak correlation between the integral flux of soft X-rays and the average velocity of the associated shock is suggested. However, for two events all of the usual flare signatures were absent, and the events are associated with the disappearance of solar filaments. It is shown that the shocks propagate isotropically over about 50 deg from the source site. Beyond 50 deg the shocks weaken particularly on their eastern flanks. As a consequence, shocks originating on the west limb cannot reach the earth. IP type II radio emission is dependent on shock velocity with faster shocks producing more intense emission. The study shows that radio intensities provide information about the evolution of IP shocks.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 191-197
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  • 63
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    Doppler scintillation observations of interplanetary shocks within 0.3 AU (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It is pointed out that more definitive shock velocity observations near the sun are needed for an improved determination of the extent of shock deceleration from the sun to earth. Woo and Armstrong (1981) have demonstrated the use of radio scattering and scintillation observations, using spacecraft signals, for measuring interplanetary shock waves near the sun. Woo and Armstrong provided the first near-sun profiles of solar wind speed and electron density fluctuation for a shock wave produced by a solar flare. The present investigation has the objective to demonstrate the use of Doppler or phase scintillations for monitoring and observing interplanetary shocks. It is also shown that Doppler noise, a parameter which is routinely observed and recorded by the NASA Deep Space Network, is essentially a measure of Doppler scintillations.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 154-162
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  • 64
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    Distant heliospheric results on interplanetary shock propagation (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Solar wind plasma data from Pioneers 10 and 11 and the Pioneer Venus Orbiter for 1978 to mid-1981 have been examined for forward shock signatures, and associations have been made with solar flares. (IMP 8 shocks from early 1978 have similarly been included for completeness). The numbers of flare-associated shocks observed at the various heliocentric distances of the spacecraft (ranging from 0.7 to 24 AU) are deduced, and the shock strengths and energies are given. Significantly fewer shocks associated with flares are observed at the greater distances, presumably because more cases have decreased below the threshold for inclusion. Three cases in which the same shock was probably detected by spacecraft at different heliocentric distances indicate deceleration and weakening at the greater distances.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 210-216
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  • 65
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    Analysis of O(7+)/O(6+) observations in the solar wind (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The ratio of O(7+)/O(6+) in the solar wind can be used to deduce the temperature at the point in the corona where the charge states become 'frozen' in the flow, and its determination therefore depends both upon the characteristics of the instrument and those of the source. The apparent increase of the ratio O(7+)/O(6+) observed in the solar wind by Ogilvie and Vogt (1980) at speeds above 450 km/s has been reevaluated using a greatly expanded data set. The ratio observed for solar wind speeds less than 450 km/s corresponds to an electron temperature of (1.7 + or - 0.2) x 10 to the 6th K in the region of 'freezing in' of the flow, as was previously reported. At higher speeds, when the kinetic temperature of the solar wind often exceeds (2-3) x 10 to the 5th K, instrumental effects become large and corrections difficult to determine.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 9881-988
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  • 66
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    The relation between hard X-ray and transition-region line emission in solar flares (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Observational evidence suggests that both the hard X-ray and ultraviolet emission from the impulsive phase of flares result from an electron beam. The results of model calculations that are consistent with this theory are presented. The impulsive phase is envisioned as occurring in many small magnetically confined loops, each of which maintains an electron beam for only a few seconds. This model successfully matches several observed aspects of the impulsive phase. The corona is heated to less than 2 million K, maximum enhanced emission occurs in lines formed near 100,000 K, and there is only slight enhancement between 100,000 and 2 million K. The slope of the observed relationship between hard X-ray and Ov 1371 A emission is also matched, but the relative emission is not. The calculations indicate that UV emission lines formed below a temperature of about 100,000 K will arise predominantly from the chromospheric region heated by the electron beam to transition region temperatures. Emission lines formed at higher temperatures will be produced in the transition region. This should be detectable in density-sensitive line ratios. To account successfully for the impulsive UV emission, the peak temperature in the impulsively heated loops must remain below about 2 million K. Thus the model implies that the impulsive heating takes place in different loops from the hotter gradual phase emission.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 96; 317-330
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  • 67
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    On the maintenance of sunspots - An ion hurricane mechanism (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Inward and downflow motions below the photosphere are considered to be a means of cooling and powering sunspot dynamics. Parker's superadiabatic effect is examined with attention focused on the energetics involved in ionization advection. The current analysis enhances Parker's mechanism by allowing for a 2 m/s downflow velocity at 2000 km depth to significantly reduce the photospheric irradiance to near umbral intensities. Similarities between sunspots and terrestrial hurricanes are noted, and it was found that ionization energy plays the same role in sunspots as latent energy plays in terrestrial weather systems. Based on the hypothesis that magnetic fields are important in organizing the motions on the sun, some understanding is provided of: (1) the instability which drives the cooling mechanism for sunspots, (2) the low latitude appearance of sunspots, (3) active region development with faculae following sunspot growth, (4) the role of the fluid in maintaining the magnetic field and the role of the field as a focal point for the fluid downflow, (5) the heating mechanism and structure of faculae, (6) energy balance in active regions, and (7) the behavior difference of pores and ephemeral active regions in relation to ordinary sunspots and active regions.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 299; 1051-106
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  • 68
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    Collisionless shocks in the heliosphere: A tutorial review (1985)
    In:  Other Sources
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    Publication Date: 2016-03-09
    Description: An update is presented on current knowledge of collisionless shocks in the heliosphere. The individual papers address: a quarter century of collisionless shock research, some macroscopic properties of shock waves in the heliosphere, microinstabilities and anomalous transport, and acceleration of energetic particles.
    Keywords: SOLAR PHYSICS
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  • 69
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    Collisionless shocks in the heliosphere: Reviews of current research (1985)
    In:  Other Sources
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    Publication Date: 2016-03-09
    Description: The present conference on heliospheric collisionless shocks considers such macrostructure-, microstructure-, and particle acceleration-related topics as interplanetary shock phenomena near and within 1 AU, as well as beyond, planetary bow shocks, shock formation and evolution in the solar atmosphere, MHD and gasdynamic theories for planetary bow waves, and subcritical collisionless shock waves. Also discussed are ion reflection, gyration, and dissipation at supercritical shocks, the numerical simulation of quasi-perpendicular collisionless shocks, electron distributions near collisionless shocks, the microtheory of collisionless shock current layers, plasma waves and instabilities, the electron foreshock, upstream suprathermal ions, and both diffusive and shock drift acceleration.
    Keywords: SOLAR PHYSICS
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  • 70
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    Ayres' bifurcated solar model (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The assumptions of Ayres' model of the upper solar atmosphere are examined. It is found that the bistable character of his model is postulated - through the assumptions concerning the opacity sources and the effect of mechanical waves, which are allowed to destroy the CO molecules but not to heat the gas. The neglect of cooling by metal lines is based on their reduced local cooling rate, but it ignores the increased depth over which this cooling occurs. Thus, the bifurcated model of the upper solar atmosphere consists of two models, one cold at the temperature minimum, with a kinetic temperature of 2900 K, and the other hot, with a temperature of 4900 K.
    Keywords: SOLAR PHYSICS
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  • 71
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    Dynamical behavior of a theoretical chromosphere model (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Time dependent calculations of a solar chromosphere model perturbed by a spectrum of short period acoustic waves superimposed on the observed power spectrum of five minute oscillations are presented. The resulting data is analyzed by Fourier techniques and discussed in terms of nonlinear interaction of various modes.
    Keywords: SOLAR PHYSICS
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  • 72
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    The excitation of helium resonance lines in solar flares (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Helium resonance line intensities are calculated for a set of six flare models corresponding to two rates of heating and three widely varying incident fluxes of soft X-rays. The differing ionization and excitation equilibria produced by these models, the processes which dominate the various cases, and the predicted helium line spectra are examined. The line intensities and their ratios are compared with values derived from Skylab NRL spectroheliograms for a class M flare, thus determining which of these models most nearly represents the density vs temperature structure and soft X-ray flux in the flaring solar transition region, and the temperature and dominant mechanaism of formation of the helium line spectrum during a flare.
    Keywords: SOLAR PHYSICS
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  • 73
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    Deduction of coronal magnetic fields using microwave spectroscopy (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Gyroresonance opacity renders the solar corona optically thick at frequencies which are low integral multiples of the local gyrofrequency. This causes the microwave spectrum of sunspots to be sensitive to the strength of coronal magnetic fields. The concept is illustrated by high spectral resolution observations of a sunspot acquired with the Owens Valley frequency-agile interferometer. The observed spectrum is compared to the results of three-dimensional atmospheric model calculations in which the sunspot field is represented by the potential field of a dipole located beneath the photosphere. The comparison enables the depth, orientation and magnetic moment of the dipole that best fits the observations to be determined. Since such observations require that the microwave emission be resolved spectrally, not spatially, the technique may be applicable to the study of stellar coronal fields.
    Keywords: SOLAR PHYSICS
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  • 74
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    Numerically-simulated formation and propagation of interplanetary shocks (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The present numerical method for simulating the formation and propagation of interplanetary shocks is based on the shock-capturing finite difference scheme of Lax (1950) and Lax and Wendroff (1960), as well as the recent method of NEAR characteristics of Nakagawa (1980, 1981). Attention is given to examples which strongly suggest that all the shocked solar wind plasma parameters due to given physical perturbations, such as flare-generated shocks, can be predicted through the use of this method; the method is, however, limited to the supersonic and super-Alfvenic flow.
    Keywords: SOLAR PHYSICS
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  • 75
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    Solar-geophysical data number 493, September 1985. Part 1: (Prompt reports). Data for August 1985, July 1985 and late data (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Topics covered include: detailed index for 1985; data for August 1985--(IUWDS alert periods (Advanced and Worldwide), solar activity indices, solar flares, solar radio emission, Stanford mean solar magnetic field); (solar active regions, sudden ionospheric disturbances, solar radio spectral observations, cosmic ray measurements by neutron monitor, geomagnetic indices, radio propagation indices); and late data--calcium plage data.
    Keywords: SOLAR PHYSICS
    Type: NASA-CR-176705 , NAS 1.26:176705 , PB86-125457
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    Solar-geophysical data number 489, May 1985. Part 2: (Comprehensive reports). Data for December 1984, March-May 1983 and miscellanea (1985)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Contents include: detailed index for 1984 to 1985; data for December 1984--(Meudon Carte Synoptique, solar radio bursts at fixed frequencies, solar X-ray radiation from GOES satellite graphs, mass ejections from the sun, active prominences and filaments, solar irradiance); and data for March, April and May 1983--(solar flares March 1983, solar flares April 1983, solar flares May 1983, number of flares August 1966 to May 1983).
    Keywords: SOLAR PHYSICS
    Type: NASA-CR-176704 , NAS 1.26:176704 , PB86-121993 , SGD-490-PT-2
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  • 77
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    Solar-geophysical data number 490, June 1985. Part 1: (Prompt reports). Data for May 1985, April 1985 and late data (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Contents include: detailed index for 1984 to 1985; data for May 1985--(IUWDS alert periods (Advance and Worldwide) solar activity indices, solar flares, solar radio emission, Stanford mean solar magnetic field); data for April 1985--(solar active regions, sudden ionospheric disturbances, solar radio spectral observations, cosmic ray measurements by neutron monitor, geomagnetic indices, radio propagation indices); and late data--(geomagnetic indices, cosmic rays, calcium plage data).
    Keywords: SOLAR PHYSICS
    Type: NASA-CR-176703 , NAS 1.26:176703 , PB86-121985 , SGD-490-PT-1
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  • 78
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    Chromosphere flare models (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Further calculated results based on the F1 and F2 chromospheric models of Machado et al. (1980) are presented in addition to results from a model with enhanced temperatures relative to the weak-flare model F1 in the upper photosphere and low chromosphere, and from a model with enhanced temperatures relative to the strong flare model F2 in the upper chromosphere. The coupled equations of statistical equilibrium and radiative transfer for H, H(-), He I-II, C I-IV, Si I-II, Mg I-II, Fe, Al, O I-II, Na, and Ca II are solved, and the overall absorption and emission of radiation by lines throughout the spectrum are determined by means of a reduced set of opacities taken from a compilation of over 10 million lines. Semiempirical models show that the white light flare continuum may arise by extreme chromospheric overheating, as well as by an enhancement of the minimum temperature region.
    Keywords: SOLAR PHYSICS
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  • 79
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    Alfvenic heating of the chromosphere and corona (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The behavior in the chromosphere of Alfven waves propagating on closed magnetic field lines (e.g. coronal loops) is considered. It is found that the observed chromospheric nonthermal velocities are consistent with the predicted behavior of Alfven waves. If they are indeed Alfven waves, then the observed motions imply energy fluxes which are sufficient to heat the corona and chromosphere. It is further shown that the observed motions can reproduce the observed chromospheric heating, if the heating occurs via a Kolmogoroff cascade. But a definitive analysis will require a self-consistent treatment of nonlinear effects.
    Keywords: SOLAR PHYSICS
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  • 80
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    A spectral analysis of the low temperature material in spicules (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The resonance lines of Na, Sr(+), and the Mg triplet system, together with the middle H Balmer lines, are used to determine the plasma parameters in the low temperature parts of spicules. Results are presented for heights of 2100 and 2500 km according to the chromospheric line emission data reported by Dunn, et al. (1968) for the 1962 eclipse. In addition to obtaining values for the electron density, this method is unique in yielding direct results for the degree of hydrogen ionization, the hydrogen density, and the line-of-sight thickness of emitting material. Temperature, microturbulence, and vertical flow velocity are more loosely determined in ranges corresponding to allowed combinations of these quantities.
    Keywords: SOLAR PHYSICS
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  • 81
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    Recent thermal models of the chromosphere (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The paper describes recent research on the calculation of solar chromospheric models. The models included here are based on the observed spectrum, and on the assumption of hydrostatic equilibrium. The calculations depend on realistic solutions of the radiative transfer and statistical equilibrium equations for optically thick lines and continua, and on including the effects of large numbers of lines throughout the spectrum. Although spectroheliograms show that the structure of the chromosphere is highly complex, one-dimensional models of particular features are reasonably successful in matching observed spectra. There has been considerable recent progress in applying such models to the interpretation of chromospheric observations.
    Keywords: SOLAR PHYSICS
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  • 82
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    Mechanisms for chromospheric heating (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A nonthermal energy source is required to heat the solar chromosphere and corona. A survey is made of the properties of waves that propagate along magnetic flux tubes, which may transport the needed energy from the convection zone to the chromosphere. It is next explored how convective motions can generate those waves. Finally, various mechanisms by which these waves may develop small scale structures and dissipate via viscosity and resistivity are discussed.
    Keywords: SOLAR PHYSICS
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  • 83
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    A simulation study of two major events in the heliosphere during the present sunspot cycle (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The two major disturbances in the heliosphere during the present sunspot cycle, the event of June to August, 1982, and the event of April to June, 1978, are simulated by the method developed by Hakamada and Akasofu (1982). Specifically, an attempt was made to simulate the effects of six major flares from three active regions in June and July, 1982, and April and May, 1978. A comparison of the results with the solar wind observations at Pioneer 12 (approximately 0.8 au), ISEE-3 (approximately 1 au), Pioneer 11 (approximately 7 to 13 au) and Pioneer 10 (approximately 16 to 28 au) suggests that some major flares occurred behind the disk of the sun during the two periods. The method provides qualitatively some information as to how such a series of intense solar flares can greatly disturb both the inner and outer heliospheres. A long lasting effect on cosmic rays is discussed in conjunction with the disturbed heliosphere.
    Keywords: SOLAR PHYSICS
    Type: NASA-CR-176943 , NAS 1.26:176943
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  • 84
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    The hard X-ray burst spectrometer event listing, 1980 - 1985 (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: This event listing is a comprehensive reference for the hard X-ray bursts detected with the Hard X-Ray Burst Spectrometer on the Solar Maximum Mission from the time of launch on February 14, 1980 to September 1985. Over 8000 X-ray events were detected in the energy range from 30 to approx. 500 keV with the vast majority being solar flares. The listing includes the start time, peak time, duration and peak rate of each event.
    Keywords: SOLAR PHYSICS
    Type: NASA-TM-86236 , REPT-86B0023 , NAS 1.15:86236
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  • 85
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    Contributions to Proceedings from the NATO Advanced Research Workshop on the Seismology of the Sun and the Distant Stars (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Advanced research results on the seismology of the Sun and distant stars is presented. Topics presented include: (1) detection of global convective wave flows; (2) observation of low degree p-mode oscillations; and (3) techniques for spectral deconvolution.
    Keywords: SOLAR PHYSICS
    Type: NASA-CR-176470 , NAS 1.26:176470 , SU-CSSA-ASTRO-85-23
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  • 86
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    The heavy ion compositional signature in 3He-rich solar particle events (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A survey of the approx. 1 MeV/nucleon heavy ion abundances in 66 He3-rich solar particle events was performed using the Max-Planck-Institut/University of Maryland and Goddard Space Flight Center instruments on the ISEE-3 spacecraft. The observations were carried out in interplanetary space over the period 1978 October through 1982 June. Earlier observations were confirmed which show an enrichment of heavy ions in HE3-rich events, relative to the average solar energetic particle composition in large particle events. For the survey near 1.5 MeV/nucleon the enrichments compared to large solar particle events are approximately He4:C:O:Ne:Mg:Si:Fe = 0.44:0.66:1.:3.4:3.5:4.1:9.6. Surprising new results emerging from the present broad survey are that the heavy ion enrichment pattern is the same within a factor of approx. 2 for almost all cases, and the degree of heavy ion enrichment is uncorrelated with the He3 enrichment. Overall, the features established appear to be best explained by an acceleration mechanism in which the He3 enrichment process is not responsible for the heavy ion enrichment, but rather the heavy ion enrichment is a measure of the ambient coronal composition at the sites where the He3-rich events occur.
    Keywords: SOLAR PHYSICS
    Type: NASA-CR-177831 , NAS 1.26:177831 , PP-86-59
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  • 87
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    Active Phenomena in the Pre-main Sequence Star AB AUR (1985)
    In:  CASI
    Details
    Publication Date: 2014-09-16
    Description: The Herbig Ae star AB Aur presents short time scale variability in the Mg II and Ca II resonance lines. A qualitative model of the expanding envelope, involving fast and slow streams in a co-rotating structure, is proposed to explain the Mg II spectral variability.
    Keywords: SOLAR PHYSICS
    Type: NASA. Goddard Space Flight Center The Origin of Nonradiative Heating(Momentum in Hot Stars; p 81-85
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  • 88
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    Magnetic Field-Vector Measurements in Quiescent Prominences via the Hanle Effect: Analysis of Prominences Observed at Pic-Du-Midi and at Sacramento Peak (1985)
    In:  CASI
    Details
    Publication Date: 2016-03-01
    Description: The Hanle effect method for magnetic field vector diagnostics has now provided results on the magnetic field strength and direction in quiescent prominences, from linear polarization measurements in the He I E sub 3 line, performed at the Pic-du-Midi and at Sacramento Peak. However, there is an inescapable ambiguity in the field vector determination: each polarization measurement provides two field vector solutions symmetrical with respect to the line-of-sight. A statistical analysis capable of solving this ambiguity was applied to the large sample of prominences observed at the Pic-du-Midi (Leroy, et al., 1984); the same method of analysis applied to the prominences observed at Sacramento Peak (Athay, et al., 1983) provides results in agreement on the most probable magnetic structure of prominences; these results are detailed. The statistical results were confirmed on favorable individual cases: for 15 prominences observed at Pic-du-Midi, the two-field vectors are pointing on the same side of the prominence, and the alpha angles are large enough with respect to the measurements and interpretation inaccuracies, so that the field polarity is derived without any ambiguity.
    Keywords: SOLAR PHYSICS
    Type: Meas. of Solar Vector Magnetic Fields; p 375-378
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  • 89
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    Correlation between solar neutrino flux and other solar phenomena (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-11
    Description: A study was made of the solar neutrino data with a tank of CC14 located 4800 mwe underground for the period 1970 to 83. These observations are on the production rates of Ar37 atoms via the reaction upsilon sub e + Cl37 yields Ar37 plus e(-) in the tank caused presumably by a flux of neutrinos from the Sun. The idea of possible time variations in the data shown is discussed and an attempt is made to correlate the variations to two other phenomena of solar origin-the sunspot number and the geomagnetic Ap index.
    Keywords: SOLAR PHYSICS
    Type: 19th Intern. Cosmic Ray Conf - Vol. 5; p 426-429; NASA-CP-2376-VOL-5
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  • 90
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    Physics of the sun (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Keywords: SOLAR PHYSICS
    Type: NASA-CR-183323 , NAS 1.26:183323 , PB88-224886
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  • 91
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    Coronal mass ejections - 1979-1981 (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: An overview of observations of coronal mass ejections (CMEs) during the interval March 28, 1979 through December 31, 1981 is presented. An introduction is first provided to the instrument used in the observations, the method of identifying CMEs, the concepts of CME structural classes, CME importance categories, and the distribution of mass ejections among these classes and categories. The properties of CMEs are given for all mass ejections regardless of their structural classes or importance categories, and then for each class and category. After a brief discussion of the instrument duty cycle, the occurrence rate is presented for all CMEs and for major CMEs, for fast CMEs only, and finally for equatorial CMEs only. The results are compared to those obtained previously.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 8173-819
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  • 92
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    White-light coronal transients observed from Skylab May 1973 to February 1974 - A classification by apparent morphology (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 97; 191-201
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  • 93
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    Correlation of solar decimetric radio bursts with X-ray flares (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Several hundred radio bursts in the decimetric wavelength range (300-1000 MHz) have been compared with simultaneous soft and hard X-ray (HXR) emission. Long lasting (type IV) radio events have been excluded. The association of decimetric emission with hard X-rays has been found to be surprisingly high (48 percent). The association rate increases with bandwidth, duration, number of structural elements, and maximum frequency. Type III-like bursts are observed up to the upper limit of the observed band. This demonstrates that the corona is transparent up to densities of about 10 to the 10th/cu cm, contrary to previous assumptions. This can only be explained in an inhomogeneous corona with the radio source being located in a dense structure. The short decimetric bursts generally occur during the impulsive phase, i.e., simultaneously with hard X-rays. The times of maximum flux are well correlated (within 2 s). The HXR emission lasts 4 times longer than the radio emission in the average. This work finds a close relationship between decimetric and HXR emission, with sufficient statistics offering additional information on the flare process.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 97; 159-172
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  • 94
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    Emerging flux in active regions (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The rates at which flux emerges in active and quiet solar regions within the sunspot belts are compared. The emerging flux regions (EFRs) were identified by the appearance of arch filament structures in H-alpha. All EFRs in high resolution films of active regions made at Big Bear in 1978 were counted. The comparable rate of flux emergence in quiet regions was obtained from SGD data and independently from EFRs detected outside the active region perimeter on the same films. The rate of flux emergence is 10 times higher in active regions than in quiet regions. A sample of all active regions in 31 days of 1983 gave a ratio of 7.5. Possible mechanisms which might funnel new magnetic flux to regions of strong magnetic field are discussed.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 97; 51-58
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  • 95
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    Application of the MHD energy principle to magnetostatic atmospheres (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The MHD energy principle is applied to the stability of a magnetized atmosphere which is bounded below by much denser fluid, as is the solar corona. The two fluids are treated as ideal; the approximation is consistent with the energy principle, and the dynamical conditions that must hold at a fluid-fluid interface are used to show that if vertical displacements of the lower boundary are permitted, then the lower atmosphere must be perturbed as well. However, displacements which do not perturb the coronal boundary can be properly treated as isolated perturbations of the corona alone.
    Keywords: SOLAR PHYSICS
    Type: Geophysical and Astrophysical Fluid Dynamics (ISSN 0309-1929); 32; 3-4; 317-331
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  • 96
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    Interplanetary conditions during 3-kHz radio-wave detections in the outer heliosphere (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Plasma waves detected by the Voyager 1 and 2 spacecraft beyond about 12 AU that may be associated with the turbulence expected at the heliopause are interpreted in terms of the characteristics of the interplanetary medium at large heliocentric distances. The low-energy charged-particle environment in the outer heliosphere during the observations of the unusual plasma-wave signals is addressed. The particle data suggest that the outer heliosphere was unusually stable and free of transient shock and particle events for the roughly eight months during the wave observations.
    Keywords: SOLAR PHYSICS
    Type: Nature (ISSN 0028-0836); 316; 243
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  • 97
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    Ly-alpha and H-alpha emission by superthermal proton beams (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Simnett and Harrison (1984) have presented a model in which 100-1000 keV protons are an energy transfer agent linking coronal mass ejections and solar flares. Orrall and Zirker (1976) suggested that such protons, incident upon the chromosphere, would produce nonthermal Ly-alpha emission after charge exchange with ambient chromospheric hydrogen atoms. The present investigation is concerned with a study of the charge-exchange mechanism proposed by Orral and Zirker. The physical theory of the formation of nonthermal Ly-alpha (and H-alpha) emission is considered, taking into account photon emission, atomic transitions, atomic equilibrium, the dominant atomic processes, and the stopping of superthermal protons. Computational results presented by Orrall and Zirker are extended.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 295; 275-284
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  • 98
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    A new property of the small-scale nonthermal motions in quiescent prominences (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Small-scale nonthermal motions are a characteristic feature of astrophysical atmospheres, which have been studied on the basis of an interpretation of high-dispersion spectral line observations. The present paper is concerned with a study based on the close-lying lines Mg double-lambda 5173, 5167 and Fe(+) lambda 5169, in quiescent prominences. A summary of Mg b2, b4, and Fe(+) b3 prominence measurements and derived model profile parameters is presented in a table, while another table contains a summary of derived temperature and microvelocity parameter values. The most important result of the reported study is the finding that the Fe(+) b3 profiles in quiescent prominences are systematically narrower than one would expect from the Mg b2 profile widths and the assumption that both lines arise in regions of common T and v.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 295; 220-232
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  • 99
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    Evidence for collisionless conduction fronts in impulsive solar flares (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The present paper is concerned with an analysis of new observations of impulsive hard X-ray and microwave bursts. The results are compared with predictions of a thermal flare model. A description is presented of the thermal model with conduction-front confinement, taking into account the development and previous applications of the model, the high-energy limit of confinement and its implications for microwave emission, the formation of a test based on the revised predictions of the model, and derived parameters. The observations and the test of the model are discussed, giving attention to instrumentation, event selection, selection of a homogeneous sample of impulsive rises,. observed and derived parameters for each rise, a correlation analysis of observed and predicted rise times, uncertainties in the measurements, consistency checks, and a comparison with results of Crannell et al. (1978).
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 295; 258-264
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  • 100
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    Directionality of bremsstrahlung from relativistic electrons in solar flares (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Angular and energy spectra of bremsstrahlung have been calculated from anisotropic electron distributions in solar flares. Results have been compared to observations of gamma-ray limb-brightening and to data on the variation of the gamma-ray spectrum with flare position on the sun.
    Keywords: SOLAR PHYSICS
    Type: NASA-TM-87509 , NAS 1.15:87509
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