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  • SOLAR PHYSICS  (1,193)
  • Deutschland
  • 1975-1979  (1,196)
  • 1
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    Malaria in Deutschland (1979)
    In:  Bundesgesundheitsblatt 22, 8-13
    Details
    Publication Date: 1979
    Description: einheimische Malaria als man-made-disease KATASTER-BESCHREIBUNG: KATASTER-DETAIL:
    Keywords: Deutschland ; Umweltmedizin ; Infektionskrankheiten
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    BIBLIOGRAPHY INKA BB
  • 2
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    Soviet short-term forecasts of active region evolution and flare activity (1979)
    In:  CASI
    Details
    Publication Date: 2009-11-16
    Description: The structure and strength of the magnetic fields of the Sun's active regions were studied to obtain information for short term forecasting. Intensity forecasts were then made using the information obtained on the gradients of the magnetic fields between sunspots of opposite polarity. A comparison of flare forecasting methods is presented.
    Keywords: SOLAR PHYSICS
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 72-88
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  • 3
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    MSFC solar activity predictions for satellite orbital lifetime estimation (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The procedure to predict solar activity indexes for use in upper atmosphere density models is given together with an example of the performance. The prediction procedure employs a least square linear regression model to generate the predicted smoothed vinculum R sub 13 and geomagnetic vinculum A sub p(13) values. Linear regression equations are then employed to compute corresponding vinculum F sub 10.7(13) solar flux values from the predicted vinculum R sub 13 values. The output is issued principally for satellite orbital lifetime estimations.
    Keywords: SOLAR PHYSICS
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 378-384
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  • 4
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    Coronal holes inferred from the Fleurs East-West solar scans (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: East-West solar scans produced daily on 692 and 1415 MHz are analyzed for the period 1968 to 1973. The analysis confirms that coronal holes are stable features displaying significantly reduced electromagnetic emission which can persist for many solar rotations. The coronal hole observations are summarized in a series of tables.
    Keywords: SOLAR PHYSICS
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 288-311
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  • 5
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    A review of short-term flare forecasting activities at Toyokawa (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Short-term forecasting of solar activity conducted at Toyokawa is briefly reviewed. The forecasts are based on microwave observations of the slowly varying component of solar radiation associated with active regions. It was found that for proton flares which take place in intense active regions, it is possible to predict their occurrence with certain accuracy, but for a certain class of proton flares which occur in a small active region or which are associated with an active region, which evolves very rapidly, or for whose which occur behind the limb, it is almost impossible to forecast their occurrence.
    Keywords: SOLAR PHYSICS
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 205-211
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  • 6
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    Solar activity predictions at Peking Observatory (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: Solar activity prediction procedures used at the Peking Observatory are briefly reviewed. Methods for short term prediction of solar proton events and the results for proton events of importance greater than 1 during the period 1974-1977 are given in detail. The characteristic values of solar cycle 21 are predicted.
    Keywords: SOLAR PHYSICS
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 154-162
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  • 7
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    Forecasting of solar energetic radiation at the forecast center of the Institute of Applied Geophysics (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: Solar energetic radiation forecasting techniques are described. The factors that are used as the basis for the forecasts are discussed.
    Keywords: SOLAR PHYSICS
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 89-103
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  • 8
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    Solar forecast and real-time monitoring needs of the Study of Energy Release in Flares (SERF) (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: Complementary, simultaneous observations of flares from as many observatories, both ground based and orbiting, as possible planned for the Solar Maximum Year are considered. The need for forecasts of solar activity on long term, one week, and two day intervals is described. Real time reporting is not needed, but daily summaries of activity and permanent records are important.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 331-339
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  • 9
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    The variability of the solar ultraviolet spectral irradiances (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: Available data on the solar spectral irradiances at wavelengths below 3100 A are extremely limited and there are major uncertainties in many of the measurements. In particular, there is major disagreement on the magnitude of the variability of the spectral irradiances over the solar cycle. The effects of different solar features on the ultraviolet spectral irradiances over both the 28 day solar rotation period and over the solar cycle are discussed. It is proposed that any attempt to predict the magnitudes of the ultraviolet spectral irradiances must take into account a long term variability of emission from quiet regions of the solar disk over the solar cycle. The need for direct long term monitoring of the ultraviolet spectral irradiances is emphasized.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 280-321
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  • 10
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    A new method of very long-term prediction of solar activity (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: A method of solar activity prediction based on the statistical relationship between the minimum value of geomagnetic activity in each 11 year cycle and the height of the next sunspot cycle is proposed. The method is applied to predict sunspot cycle 21.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 258-263
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  • 11
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    The needs for prediction and real-time monitoring for the flare build-up study (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: Similarities between plasma instabilities occurring in the magnetospheric tail and in active regions on the Sun are discussed. Intense observations of the flare build-up processes on the Sun planned for May and June 1980 as a part of the Solar Maximum Year are described.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 322-330
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  • 12
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    New methods for predicting the magnitude of sunspot maximum (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: Three new and independent methods of predicting the magnitude of a forthcoming sunspot maximum are suggested. The longest lead time is given by the first method, which is based on a terrestrial parameter measured during the declining phase of the preceding cycle. The second method, with only a slightly shorter foreknowledge, is based on an interplanetary parameter derived around the commencement of the cycle in question (sunspot minimum). The third method, giving the shortest prediction lead-time, is based entirely on solar parameters measured during the initial progress of the cycle in question. Application of all three methods to forecast the magnitude of the next maximum (Cycle 21) agree in predicting that it is likely to be very similar to that of Cycle 18.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 264-279
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  • 13
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    Long-term solar activity predictions (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: The need for long term solar activity predictions is addressed. The spatial organization of solar activity is described including applications for predictions, and ancient evidence for solar variability. Methods of predicting sunspot numbers are discussed. The inherent accuracy of the methods varies considerably, but a typical error bar 20%. The accuracy of sunspot cycle predictions is considered along with long term predictions of great solar events.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 246-257
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  • 14
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    Very large geomagnetic disturbance during sunspot cycle 21: A prediction (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: Evidence is presented which suggests that very large geomagnetic disturbances (350 gammas or greater at an invariant magnetic latitude of 50 degrees) occur once or twice per sunspot cycle, on the average. There is also some tendency for these disturbances to group in large odd numbered sunspot cycles similar to the current cycle, cycle 21. No such disturbance was noted during the past cycle although a series of major solar flares was observed in August 1972. At least one very large geomagnetic disturbance is expected during the current cycle; a prediction with perhaps serious consequences for electric power companies.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 193-197
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  • 15
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    PPS76: A computerized event mode solar proton forecasting technique (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: A procedure was developed to generate a computerized time intensity profile of the solar proton intensity expected at the Earth after the occurrence of a significant solar flares on the Sun. A combination of many pieces of independent research and theoretical results are included. A construction of selected experimental and theoretical results from the entire domain of solar terrestrial physics is given.
    Keywords: SOLAR PHYSICS
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 406-427
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  • 16
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    Short-term solar activity forecasting (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: A method of forecasting the level of activity of every active region on the surface of the Sun within one to three days is proposed in order to estimate the possibility of the occurrence of ionospheric disturbances and proton events. The forecasting method is a probability process based on statistics. In many of the cases, the accuracy in predicting the short term solar activity was in the range of 70%, although there were many false alarms.
    Keywords: SOLAR PHYSICS
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 176-181
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  • 17
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    Spiral sunspots and solar activity forecasts (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: The definition of a spiral sunspot is given. Three examples are described which illustrate the processes of the occurrence of spiral sunspots and the roles played by them in prominence and flare activities. A method for solar activity forecasts is then proposed making use of parameters such as spiral sunspots, prominences and neutral lines.
    Keywords: SOLAR PHYSICS
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 140-153
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  • 18
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    Long-term forecasting of solar activity (1979)
    In:  CASI
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    Publication Date: 2006-01-16
    Description: Corrections to the forecast of the basic parameters of the 21st cycle are described. Estimates about the level of solar activity in the 22nd cycle are presented.
    Keywords: SOLAR PHYSICS
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 163-175
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  • 19
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    New atomic data of O/2+/ (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: New atomic data are tabulated for the ion O(2+). Collision strengths are calculated for several energies of the exciting electron. The populations of the levels of O(2+) are calculated as a function of electron density under conditions appropriate for the solar atmosphere. The available solar data are compared with theoretical predictions of relative line intensities.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 76; 3, Ju; July 197
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  • 20
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    Magnetic dips in the solar wind (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Using magnetic data from the Helios-1 fluxgate magnetometer, with a 0.2 s resolution, we have investigated the structure of several interplanetary discontinuities involving magnetic dips and rotations of the magnetic field vector. A minimum variance analysis illustrates the behaviour of the magnetic field through the transition. Using this analysis, quite different structures have been isolated and, in particular, narrow transitions resembling almost one dimensional reconnected neutral sheets. For the thinner cases (scale lengths of the magnetic rotation of the order or smaller than 1000 km), we find that the observed structures can be the nonlinear effect of a resistive tearing mode instability having developed on an originally one dimensional neutral sheet at the solar corona.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 62; May 1979
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  • 21
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    Solar wind heavy ions from flare-heated coronal plasma (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Information concerning the coronal expansion is carried by solar-wind heavy ions. Distinctly different energy-per-charge ion spectra are found in two classes of solar wind having the low kinetic temperatures necessary for E/q resolution of the ion species. Heavy-ion spectra which can be resolved are most frequently observed in the low-speed interstream (IS) plasma found between high speed streams; the streams are thought to originate from coronal holes. Although the sources of the IS plasma are uncertain, the heavy-ion spectra found there contain identifiable peaks of O, Si, and Fe ions. Such spectra indicate that the IS ionization state of O is established in coronal gas at a temperature of approximately 1.6 million K, while that of Fe is frozen in farther out at about 1.5 million K. On occasion anomalous spectra are found outside IS flows in solar wind with abnormally depressed local kinetic temperatures. The anomalous spectra contain Fe(16+) ions, not usually found in IS flows, and the derived coronal freezing-in temperatures are significantly higher. The coronal sources of some of these ionizationally hot flows are identified as solar flares.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 62; May 1979
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  • 22
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    Hydromagnetic waves and turbulence in the solar wind (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The paper presents a state-of-the-art review of interplanetary fluctuations, their origins, and their effects on the solar wind. Typical values of parameters to waves and turbulence in the solar wind are examined, along with a classification of large-amplitude waves. Cases where description by the MHD theory is qualitatively correct and where it can be misleading are noted. An attempt is made to state rigorously the essential points of hydromagnetic-wave theory and to identify areas in which theoretical research needs to be extended. The review covers the observed hydromagnetic fluctuations, their interpretation in terms of current theory, and the degree of closure between observation and theory. The spatial distribution and origins of waves in the solar wind are discussed.
    Keywords: SOLAR PHYSICS
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  • 23
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    Coronal hole boundary brightness in lambda 284 of Fe XV (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 62; June 197
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  • 24
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    NASA's search for the solar connection. I (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: NASA's solar research, which leans toward the study of the sun as a star, is surveyed. The Orbiting Solar Observatory (OSO) program is covered, which yielded data such as spectras of 140-400 A wavelength of the entire solar disk. Attention is also given to the results obtained by Skylab, such as data showing that whenever a large coronal hole exists near the sun's equator, a stream of high-speed solar wind will be observed at the earth. Finally areas of future research, such as a concerted study of flare phenomenon, are discussed.
    Keywords: SOLAR PHYSICS
    Type: Sky and Telescope; 58; Aug. 197
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  • 25
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    The source of electrostatic fluctuations in the solar-wind (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Solar wind electron and ion distribution functions measured simultaneously with or close to times of intense electrostatic fluctuations are subjected to a linear Vlasov stability analysis. Although all distributions tested were found to be stable, the analysis suggests that the ion beam instability is the most likely source of the fluctuations.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 84; May 1
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  • 26
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    A graphical summary of solar wind electron content observations by Pioneer 6, 8, and 9 (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Between 1965 and 1972, solar wind density measurements were obtained by Mariner 5 and Pioneer 6, 7, 8, and 9 using a radio science method called the 'dual-frequency experiment'. The measurements and data processing are now terminated. A graphical summary is presented of the best of the resulting data, showing the average electron number density of the solar wind across radio paths that vary in length up to 1.8 AU and that lie broadside to the flow direction. These graphs summarize 3.4 years of observations with a time resolution of 1 hour; the measurements provided 1-min resolution and spanned 7 years. Because the orientation and length of the paths change continually and have a major influence on the interpretation of these data, a spacecraft trajectory chart and a plot of the corotation interval are provided.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 84; Feb. 1
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  • 27
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    The N III and O IV intersystem multiplets as density indicators for solar plasmas (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The usefulness of the relative intensities of lines within the N III intersystem multiplet near 1750 A as an electron density indicator for solar plasmas is discussed. Although the relative intensities of lines in the multiplet are density sensitive, the intensity ratios should at present be used with caution. Errors of the order of 20% in transition probabilities and excitation rate coefficients can lead to order of magnitude errors in density determinations. It is demonstrated that the intensity ratio of one of the N III intersystem lines and an allowed line from a different ion may also be used as a density indicator in the 10 to the 9th to 10 to the 11th per cu cm regime.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 79; 3, No; Nov. 197
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  • 28
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    Long-term solar wind electron variations between 1971 and 1978 (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Imp solar wind electron data measured between 1971 and 1978 were studied with the aim of determining long-term variations near the earth. Two separate sets of parameter variations were observed: (1) in 1976-1977 the solar wind density, the electron temperature, and the interplanetary electrostatic potential were all enhanced, and (2) the halo density and associated electron parameters were all depressed during a 1 1/2-year period centered on the last 6 months of 1976. Although interpretation of these results in terms of corresponding coronal and interplanetary variations is not unique, it may be significant that measured solar wind parameters near the minimum of solar cycle 20 agree better with the Hartle-Sturrock model of the coronal expansion than they do during other epochs.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 84; Dec. 1
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  • 29
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    The Fe XXI lambda1354 line in solar flares observed from Skylab and its implications on ionization equilibrium calculations (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 233
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  • 30
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    EUV limb spectra of a surge observed from Skylab (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The EUV spectra of a surge observed at plus 8 in. and plus 20 in. above the white light limb from Skylab are examined. The shape of the differential emission measure determined at 8 in. and 20 in. is nearly the same as for a quiet Sun spectrum at 8 in., but the emission measure of the surge at 8 in. is about an order of magnitude greater than for the quiet Sun. At 20 in. the emission measure of the surge is initially close to the quiet Sun distribution, but decreases by a factor of 4 within 6 min. The optically thin lines formed near 10 to the 5th power K show nonthermal broadening at 8 in., and electron densities near this temperature are derived from intersystem to resonance ratios. The volume of the emitting plasma at 8 in. above the limb was determined, concluding that a continuous energy input is required to explain the observations.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 78; 3, Oc; Oct. 197
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  • 31
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    New atomic data for Si/6+/, S/8+/ and Ar/10+/ (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The paper gives new atomic data, populations of excited levels, and line intensity ratios for the ions Si VII, S IX, and Ar XI of the O I isoelectronic sequence. Ten levels are included in the calculations, i.e., the levels of the 2s/2/2p/4/ and 2s2p/5/ and 2p/6/ configurations. It is noted that the calculations are done for applications to solar plasmas. The line ratios (2s/2/2p/4/3P1 - 2s2p/5/3P0) / (2s/2/2p/4/3P1 - 2s2p/5/3P1) and (2s/2/2p/4/1D2 - 2s2p/5/1P/1/) / (2s/2/2p/4/3P/1/ - 2s1p/5/3P/1/) are two of the ratios useful for electron density determination. Finally, density sensitive line ratios of Ca XIII and Fe XIX are also discussed.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 80; 1, No; Nov. 197
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  • 32
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    Principal component analysis of solar flares in the soft X-ray flux (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The paper considers principal component analysis of solar flares in the soft X-ray flux, a technique for extracting the salient features from a mass of data. The method applies particularly to the analysis of nonstationary ensembles, and its computations require the evaluation of eigenvalues of matrices. The Eispack matrix eigen system routines were used to analyze full-disk proportional-counter data from the X-ray event analyzer which was part of the Skylab experiment. Empirical orthogonal functions were derived for events in the soft X-ray spectrum between 2.5 and 20 A during different time periods, indicating that about 90% of the cumulative power of each analyzed flare is contained in the largest eigenvector. The first two largest eigenvectors are sufficient for an empirical curve fit through the raw data and a characterization of solar flares in the soft X-ray flux, and power spectra of two largest eigenvectors reveal a reported periodicity of about 5 min.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 80; 2, De; Dec. 197
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  • 33
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    Nonlinear stability of solar type III radio bursts. II - Application to observations near 1 AU (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A set of rate equations including strong turbulence effects and anomalous resistivity are solved using parameters which model several solar type III bursts. Analysis of these bursts has led to quantitative comparisons between several of the observed phenomena and the theory. Through use of an analytic model for the time evolution of the energetic electron exciter, it is found that the exciter distributions observed at 1 AU are unstable to the excitation of the linear bump-in-tail instability, amplifying Langmuir waves above the threshold for the oscillating two-stream instability (OTSI). The OTSI and the attendant anomalous resistivity produce a rapid spectral transfer of Langmuir waves to short wavelengths, out of resonance with the electron exciter. In addition, the various parameters needed to model the bursts are extrapolated inside 1 AU with similar results. Finally, reabsorption of the Langmuir waves by the beam is shown to be unimportant in all cases, even at 0.1 AU.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 234
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  • 34
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    Solar cycle variations in IMF intensity (1979)
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    Publication Date: 2011-08-17
    Description: Annual averages of logarithms of hourly interplanetary magnetic field (IMF) intensities, obtained from geocentric spacecraft between November 1963 and December 1977, reveal the following solar cycle variation. For 2-3 years at each solar minimum period, the IMF intensity is depressed by 10-15% relative to its mean value realized during a broad 9-year period centered at solar maximum. No systematic variations occur during this 9-year period. The solar minimum decrease, although small in relation to variations in some other solar wind parameters, is both statistically and physically significant.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 84; Oct. 1
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  • 35
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    Solar variability and ozone (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Stratospheric temperature and concentration of ozone above 26 km, as measured by rocket-borne instruments, showed an increase from 1964 to 1969-70, and a decline between 1970 and 1975, closely following the solar cycle, which peaked in 1969 (+0.89 correlation at both 35 and 50 km). Similar correlations were found between the ozone density and the 10.7 cm solar radio flux (as measured by the Nimbus IV satellite), and between ozone column density and the Lyman-alpha flux, both observations being taken over the same 10 month period. A mechanism is hypothesized which would link solar flux variation with both changes in stratospheric temperature and concentration of ozone (which is produced by the photodissociation of stratospheric oxygen molecules by solar radiation in the ultraviolet wavelength region).
    Keywords: SOLAR PHYSICS
    Type: New Scientist; 84; Nov. 15
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  • 36
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    Nonlinear stability of solar type III radio bursts. I - Theory (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A theory of the excitation of solar type III bursts is presented. Electrons initially unstable to the linear bump-in-tail instability are shown to rapidly amplify Langmuir waves to energy densities characteristic of strong turbulence. The three-dimensional equations which describe the strong coupling (wave-wave) interactions are derived. For parameters characteristic of the interplanetary medium the equations reduce to one-dimension. In that case the oscillating two-stream instability (OTSI) is the dominant nonlinear instability. OTSI is stabilized through the production of nonlinear ion density fluctuations that efficiently scatter Langmuir waves out of resonance with the electron beam. An analytical model of the electron distribution function is also developed which is used to estimate the total energy losses suffered by the electron beam as it propagates from the solar corona to 1 AU and beyond.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 234
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  • 37
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    The core electron temperature profile between 0.5 and 1.0 AU in the steady-state high speed solar wind (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 84; Aug. 1
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  • 38
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    NASA's search for the solar connection. II (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A survey of future space missions planned to investigate the sun and how its events affect the earth is presented. The International Solar-Polar mission, scheduled for 1983, is designed to investigate the three-dimensional structure of the solar-wind flow and to study the corona from above the sun's poles. The Spacelab mission will make major contributions to solar study by employing a 1.25 m telescope for observations from the near violet to the near infrared wavelengths with an angular resolution of 0.1 arc sec, and will be capable of resolving features on the sun 72 km across. Other missions, including the International Sun-Earth Explorer and the solar cycle and dynamic mission, which is designed to study the global oscillations of the sun, are also discussed.
    Keywords: SOLAR PHYSICS
    Type: Sky and Telescope; 58; Sept
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  • 39
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    Variations of the sun's radius and temperature due to magnetic buoyancy (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Nature; 280; Aug. 23
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  • 40
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    Solar activity cycle during classical antiquity (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Early accounts of phenomena that may be identified as auroral displays have been abstracted from reports of unusual celestial prodigies in the classical literature. An extensive catalog of ancient aurorae and a new mathematical method of analyzing fragmentary time series of observations have been used to demonstrate, provisionally, that an auroral cycle actually existed in antiquity, at least during the 2nd century BC, and that it had an average length and amplitude comparable with those of the modern auroral cycle. On the reasonable supposition that solar activity has always been the factor responsible for aurorae, it can be concluded that the solar cycle two millennia ago was very similar to what it is today.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 77; 1-2,; Aug. 197
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  • 41
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    Solar radio spectrum extended to 10 km wavelength (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Solar radio spectra for quiet times and radio bursts in the wavelength range from 1 mm to 10 km are presented. Solar nonthermal emission in the range of 100 m to 10 km was monitored by means of long wire antennas connected to multi-channel radiometers in the frequency range 25 kHz to 10 MHz on board the IMP-6 and RAE-1 satellites. Flux densities for very intense type III bursts with intensities ranging from 10 to the -18th to 10 to the -14th W/sq m per Hz with maxima at 330 to 1500 m are shown, and a power-law wavelength distribution function of maximum burst intensities is derived. Intensities of a large type III noise storm are shown to increase with increasing wavelength to a peak near 500 m. The flux densities of both types of burst emission are observed to greatly exceed quiet sun intensities at long wavelengths.
    Keywords: SOLAR PHYSICS
    Type: Nature; 280; Aug. 16
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  • 42
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    On solar cosmic rays (1979)
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    Publication Date: 2011-08-17
    Description: The report summarizes the major results obtained over the last four years in the following areas: (1) transport in interplanetary space which includes solar particle observations combined with theoretical efforts to develop models which simulate the dynamics of the event; (2) transport in the solar corona and release of particles in the interplanetary medium; and (3) characteristics of source spectra and acceleration models. Modelling the propagation of solar cosmic rays through interplanetary space and establishing the magnitude and the radial and energy dependence of the diffusion coefficient K are considered. An important result due to statistical observation is that the coronal propagation must be independent of or weakly dependent on both rigidity and energy. Increasing evidence is found for prolonged injection at the sun.
    Keywords: SOLAR PHYSICS
    Type: Reviews of Geophysics and Space Physics; 17; June 197
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  • 43
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    Dielectronic recombination rates, ionization equilibrium, and radiative energy-loss rates for neon, magnesium, and sulfur ions in low-density plasmas (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Results of detailed and systematic calculations are presented for the total dielectronic recombination rate coefficients for the ions of Ne, Mg, and S in a low-density predominantly hydrogen plasma. The new recombination rates are used to calculate solar corona ionization-equilibrium distributions of the ions. The most important effect of dielectronic recombination for ions in corona equilibrium is found to be a shift in the maximum-abundance temperatures toward higher temperatures, which are in some cases reduced from those predicted on the basis of the simple Burgess formula.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 230
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  • 44
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    Proton-driven electromagnetic instabilities in high-speed solar wind streams (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Electromagnetic instabilities of the field-aligned, right-hand circularly polarized magnetosonic wave and the left-hand circularly polarized Alfven wave driven by two drifted proton components are analyzed for model parameters determined from Imp 7 solar wind proton data measured during high-speed flow conditions. Growth rates calculated using bi-Lorentzian forms for the main and beam proton as well as core and halo electron velocity distributions do not differ significantly from those calculated using bi-Maxwellian forms. Using distribution parameters determined from 17 measured proton spectra, we show that considering the uncertainties the magnetosonic wave may be linearly stable and the Alfven wave is linearly unstable. Because proton velocity distribution function shapes are observed to persist for times long compared to the proton gyroperiod, the latter result suggests that linear stability theory fails for proton-driven ion cyclotron waves in the high-speed solar wind.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 84; Feb. 1
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  • 45
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    Approximations for proton excitation - Erratum and extension (1979)
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    Publication Date: 2011-08-17
    Description: Kastner (1977) proposed relatively simple approximations for proton excitation in coronal ions, which yield both excitation rate coefficients and excitation cross sections. An error in Kastner's expression for one of the partial excitation rate coefficients is corrected. The expression for excitation cross section is extended to higher energies, and the resulting expression for the other partial rate coefficient is given. Results obtained with the corrected and extended total excitation rate coefficient are presented for several representative transitions in Ca XIII, Ca XV, Fe X, Fe XIII, Fe XIV, Fe XVIII, and S X. The corrected and extended approximation is expected to yield excitation rates reliably within 50%.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 71; 1-2,; Jan. 197
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  • 46
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    Physics of the solar wind for the 1975-1978 IUUG Quadrennial Report (1979)
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    Publication Date: 2011-08-17
    Description: The paper surveys topics related to the origin, expansion, and acceleration of the solar wind and the plasma physics of the interplanetary medium. The study of the relationship between coronal holes and solar-wind streams, and the associated revision of ideas about solar wind acceleration and heating are reviewed. In addition, topics of hydromagnetic waves and turbulence, and interplanetary electrons, as items of particular importance during the past quadrennium, are discussed. While the research discussed was concerned with data taken near solar minimum, further solar-wind studies will concentrate on observations from the rising and maximum phases of the solar cycle.
    Keywords: SOLAR PHYSICS
    Type: Reviews of Geophysics and Space Physics; 17; June 197
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  • 47
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    XUV electron density diagnostics for solar flares (1979)
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    Publication Date: 2011-08-17
    Description: Potential electron-density diagnostics for the high-temperature component of solar flares are studied with reference to the wavelength region from 171 to 630 A. The specific ions discussed include Fe IX through Fe XV, Ni XI through Ni XVII, and ions in the beryllium, boron, carbon, and nitrogen isoelectronic sequences. Line ratios that could be useful as density indicators under solar-flare conditions are indicated, available data for the ions considered are reviewed, and several theoretical intensity ratios are plotted. The results are employed to determine the electron-density distribution as a function of electron temperature for several spectra from two flares. For these flares it is found that the electron density increases from 10 billion to 500 billion per cu cm for a temperature increase from 1 million to 10 million K.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal Supplement Series; 40; June 197
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  • 48
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    Magnetic fields, plasmas, and coronal holes - The inner solar system (1979)
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    Publication Date: 2011-08-17
    Description: Recent results concerning streams and magnetic fields in the inner solar system are reviewed. Observations have shown that MHD streams are bounded by thin shear layers within 1 AU, probably because they originate in coronal holes which have sharp boundaries. The properties of Alfvenic fluctuations in streams cannot be fully explained on the basis of the hypothesis that they are plane, transverse Alfven waves. A more complete and accurate description might be that they represent nonplanar general Alfven waves weakly coupled to a compressive mode and moving through a medium containing tangential discontinuities and other convected inhomogeneities.
    Keywords: SOLAR PHYSICS
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  • 49
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    A theory of local and global processes which affect solar wind electrons. I - The origin of typical 1 AU velocity distribution functions - Steady state theory (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A kinetic theory for the velocity distribution of solar wind electrons which illustrates the global and local properties of the solar wind expansion is proposed. By means of the Boltzmann equation with the Krook collision operator accounting for Coulomb collisions, it is found that Coulomb collisions determine the population and shape of the electron distribution function in both the thermal and suprathermal energy regimes. For suprathermal electrons, the cumulative effects of Coulomb interactions are shown to take place on the scale of the heliosphere itself, whereas the Coulomb interactions of thermal electrons occur on a local scale near the point of observation (1 AU). The bifurcation of the electron distribution between thermal and suprathermal electrons is localized to the deep solar corona (1 to 10 solar radii).
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 84; June 1
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  • 50
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    The high-temperature corona associated with a loop prominence system (1979)
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    Publication Date: 2011-08-17
    Description: Flare-associated coronal loops were observed on the SE limb of the sun of 1972 February 9 by the Goddard X-ray and EUV spectroheliograph on board OSO 7. The loop structure is clearly visible in the lines of Mg VIII and Mg IX, whereas little or no detail is observed in Fe XV and Fe XVI. A looplike structure with a cloud of emission at the top is observed in soft X-rays. The temperature structure in the region has been calculated from the ratio Fe XVI/Fe XV. The isothermal contour plot is strikingly similar to the isointensity contour plots of the soft X-ray spectroheliograms. With these temperatures and the Fe XV intensity calculated from a calibration scheme developed by Chapman and Neupert, the emission measure has been estimated in the loops. Calculated energy losses suggest that continued deposition of energy is required over the observing period.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 229
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  • 51
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    Solar gamma rays above 8 MeV (1979)
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    Publication Date: 2011-08-17
    Description: Processes that lead to the production of gamma rays with energy greater than 8 MeV in solar flares are reviewed and evaluated. Excited states that can be produced by inelastic scattering, charge exchange, and spallation reactions in the abundant nuclear species are considered in order to identify nuclear lines that may contribute to the gamma-ray spectrum of solar flares. The flux of 15.11-MeV gamma rays relative to the flux of 4.44-MeV gamma rays from the deexcitation of the corresponding states in C-12 is calculated for a number of assumed distributions of exciting particles. This flux ratio is shown to be a sensitive diagnostic of accelerated particle spectra. Other high-energy nuclear levels are not so isolated as the 15.11-MeV state and are not expected to be so strong. The spectrum of gamma rays from the decay of neutral pions is shown to be sensitive to the energy distribution of particles accelerated to energies greater than 100 MeV.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 229
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  • 52
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    Nonthermal broadening of extreme ultraviolet emission lines near the solar limb (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 73; 3, Ma; Mar. 197
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  • 53
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    On the nonthermal excitation and polarization of X-ray lines during solar flares (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The energy distributions of nonthermal electrons are derived from hard X-ray spectra taken during the impulsive phase of two 2B flares in February 1969. They are used to calculate the fluxes of nonthermally excited X-ray lines of hydrogen-like and helium-like ions. These fluxes are compared to the total line fluxes observed at the same time with crystal spectrometers. The nonthermal excitation is found to give only small contributions to the total line intensities. This implies that the impact polarization which is to be expected for anisotropic velocity distributions of the energetic electrons, will be low. Nevertheless it should be feasible to detect line polarization during the impulsive phase of strong X-ray flares.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 61; Feb. 197
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  • 54
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    The coronal atmosphere above solar active regions - Comparison of high spatial resolution soft X-ray and centimetric observations (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: High spatial resolution observations of solar active regions in soft X-rays and centimetric wavelengths are compared using X-ray and radio data obtained during the 1973 Skylab mission. An overall correspondence in position and size between regions of enhanced X-ray emission and regions of enhanced microwave emission was noticed. However, a closer analysis of the findings suggested that substantial differences exist between the emission properties of the atmosphere over sunspots and that over plages, with the difference probably related to the average intensity of the magnetic field, which was found to be higher over sunspot umbrae than over plage areas.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 229
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  • 55
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    On the structure of the solar transition zone and lower corona (1979)
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    Publication Date: 2011-08-17
    Description: Recent observations of the solar transition zone and corona obtained primarily from NRL spectrographs on Skylab are summarized and used to examine the structure of the transition zone. The transition zone is revealed to be more inhomogeneous than is apparent from spectroheliograms with spatial resolution of about 3 arcsec. Transition-zone emission appears to arise in spicularlike structures. The effective area covered by the emitting structures at lower transition-zone temperatures (about 100,000 K) is only about 1% of the total surface area of the sun. The transition zone is highly inhomogeneous even over cell interior regions, where fluctuations in brightness by factors of 25 can occur. It is shown that homogeneous coronal models are not valid for the inner corona. Most of the higher-density inner corona is concentrated into looplike structures that extend down to the white-light limb. These structures are unrelated to the spicular-type structures that produce most of the transition-zone emission.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 229
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  • 56
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    Fe XXI as an electron density diagnostic in solar flares (1979)
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    Publication Date: 2011-08-17
    Description: Atomic data have been calculated for Fe XXI, and the theoretical intensity ratios for many transitions are tabulated. Fe XXI lines in wavelength regions 1-25 A, 90-200 A, and 300-2500 A are discussed with reference to presently available solar and laboratory spectra. It is found that Fe XXI is an excellent density diagnostic for solar-flare and tokamak plasmas, when densities are in the range from 10 to the 11th to 10 to the 15th per cu cm. The theoretical calculations are applied to flare spectra obtained from OSO 5, and an electron density of less than 10 to the 13th per cu cm is deduced for a temperature of 10,000,000 K. The results are somewhat ambiguous in several cases because of the limited spectral and temporal resolution of these earlier spectrometers. However, the calculations will be important for forthcoming solar projects, such as the Solar Maximum Mission.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 73; 1-2,; Mar. 197
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  • 57
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    Spectral evolution of multiply impulsive solar bursts (1979)
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    Publication Date: 2019-06-27
    Description: Some results from the analysis of a set of multiply impulsive hard X-ray and microwave solar bursts are presented, showing that some bursts can exhibit widely different magnetic-field strengths at different times. Two categories of microwave spectral behavior are identified: those events during which the microwave turnover frequency (MTF) and spectral shape (SS) remain the same from peak to peak, and those during which the MTF and SS change significantly. These categories correspond to two classes of multiply impulsive bursts: those for which the emission can be characterized by a constant magnetic field and therefore a single source region, and those in which groups of component spikes appear to originate in regions of different magnetic-field strengths, corresponding to separate source regions which flare sequentially. With regard to the latter type, examples are presented, the discrete flaring regions are examined, and their spatial separations are estimated.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 234
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  • 58
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    A study of solar flare electron events from October 1972 through December 1974 from Imp 7 and 8 (1979)
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    Publication Date: 2019-06-27
    Description: Data from the Johns Hopkins University Applied Physics Laboratory Charged Particle Measurement Experiment aboard Imp H and J were searched for solar flare produced intensity increases in greater than 0.2-MeV electrons during the 26-month period from October 1972 through December 1974. Of the 44 solar electron events found during this period, 31 were isolated for a detailed statistical study. Systematics among the characteristics of the electron profiles (e.g., peak intensity times and count rates) and those of the associated flares (e.g., H-alpha onset times, H-alpha importance class, heliocentric coordinates, etc.) were examined, and the significant results are presented in several scatter plots. The results reveal that the time delay between the flare onset and the arrival of the peak electron intensity at 1 AU (time to maximum) is a function of the flare's deviation in heliolongitude from the solar region which was well connected to the earth via a magnetic flux tube; the well-connected flares produced electron intensity maxima in the least time.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 84; Dec. 1
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  • 59
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    The gyrosynchrotron emission from quasi-thermal electrons and applications to solar flares (1979)
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    Publication Date: 2019-06-27
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 234
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  • 60
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    High-resolution observations of the quiet sun at 6 centimeters using the Westerbork Synthesis Radio Telescope (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 234
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  • 61
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    Thermal instabilities in magnetically confined plasmas - Solar coronal loops (1979)
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    Publication Date: 2019-06-27
    Description: The thermal stability of confined solar coronal structures ('loops') is investigated, following both normal mode and a new, global instability analysis. It is demonstrated that: (1) normal mode analysis shows modes with size scales comparable to that of loops to be unstable, but to be strongly affected by the loop boundary conditions; (2) a global analysis, based upon variation of the total loop energy losses and gains, yields loop stability conditions for global modes dependent upon the coronal loop heating process, with magnetically coupled heating processes giving marginal stability. The connection between the present analysis and the minimum flux corona of Hearn is also discussed.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 234
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  • 62
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    A Doppler measurement with low scattered light of the higher rotation rate of sunspot magnetic fields at the photosphere (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 234
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  • 63
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    The effect of magnetic fields on solar luminosity (1979)
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    Publication Date: 2019-06-27
    Description: The paper presents an investigation into the influence of magnetic fields in sunspots and faculae on solar luminosity, using measurements of the solar constant from ground level and from space. Attention is given to an analysis that shows that it is difficult to devise an atmospheric mechanism that would rapidly lower visible and infrared transmission in response to sunspots, increase it in response to faculae, and anticipate the magnetic development of these features by about one day. It is shown that the phase shift of the luminosity variation provides a promising new technique to determine the depth at which the magnetic fields of sunspots and faculae redistribute the flow of convective energy.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 234
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  • 64
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    Relationship between hard X-ray and EUV sources in solar flares (1979)
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    Publication Date: 2019-06-27
    Description: The high time resolution hard X-ray (not less than 15 keV) observations of medium and large impulsive solar flares made with the OSO 5 satellite are compared with the simultaneous ground-based observations of 10-1030 A EUV flux made via sudden frequency deviations (SFD) at Boulder. For most flares the agreement between the times of maxima of the impulsive hard X-ray and EUV emissions is found to be consistent with earlier studies (not less than 1 s). The rise and decay times of the EUV emission are larger than the corresponding times for X-rays not less than 30 keV. When OSO 5 hard X-ray measurements are combined with those made by OGO1, OGO 3, OGO 5, and TD 1A satellites, it is found that there is a nearly linear relationship between the energy fluxes of impulsive EUV emission and X-rays not less than 10 keV over a wide range of flare magnitudes. A model involving only a 'partial precipitation' of energetic electrons and consisting of both thick and thin target hard X-ray sources is examined.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 234
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  • 65
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    Solar energetic particles - From the corona to the magnetotail (1979)
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    Publication Date: 2019-06-27
    Description: Some new results concerning coronal and interplanetary propagation of energetic particles are discussed in the context of previous and current observations and interpretations. Evidence is presented that the bulk of protons of approximately 1 MeV can be preferentially injected onto interplanetary field lines at coronal longitudes and latitudes well-removed (approximately 60 deg) from the site of the associated active region. For these protons, interplanetary propagation parallel and transverse to the interplanetary field evidently involves little scattering near 1 AU, so that parallel propagation is approximately 'scatter free' and transverse propagation is primarily that due to the E x B drift. Upstream of the earth's bow shock, both intensities and anisotropies of approximately 1-MeV protons and electrons are significantly modified by the magnetosphere, and these effects may provide a probe of the structure of the bow shock and magnetosheath in regions not readily accessible to spacecraft.
    Keywords: SOLAR PHYSICS
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  • 66
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    Radio interferometric observations of solar bursts at 3.7 and 11.1 cm wavelengths (1979)
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    Publication Date: 2019-06-27
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 64; Nov. 197
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  • 67
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    The height structure of solar active regions at X-ray wavelengths as deduced from OSO-8 limb crossing observations (1979)
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    Publication Date: 2019-06-27
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 64; Nov. 197
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  • 68
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    The heating of the temperature minimum region in solar flares - A reassessment (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The paper discusses and evaluates the suggestions made by Machado et al. (1978) on how to reconcile the observed temperature enhancements at temperature-minimum levels in solar flares with some theoretical heating mechanism. The objective is to gain deeper insight into the nature of the photospheric flare. The discussion focuses on the validity of the assumption of H(-) LTE at temperature-minimum levels, as well as on EUV irradiation and Joule heating by steady currents as heating mechanisms. It is found that, unless there are strong inhomogeneities associated with either heating mechanism, neither can reasonably be reconciled with observations. It is concluded that detailed high-resolution (both spatial and temporal) measurements are necessary to further the present understanding of the flare process at temperature-minimum levels.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 64; Nov. 197
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  • 69
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    Echelle observations of C III lambda 1909 and Si III lambda 1892 (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Profiles of C III 1909 and Si III 1892 obtained on and near the limb during the 1976 flight of the University of Hawaii echelle rocket spectrograph were reduced and analyzed to determine electron densities and mass motions. The electron pressure derived agrees well with that determined by Cook and Nicolas (1979) from ATM data. Nonthermal velocities in the region of formation of Si III 1892 on the disk were found to be 10-12 km/s, somewhat lower than the values obtained by Doschek et al. (1976), also from ATM spectra. However, velocities derived at and above the limb were in closer agreement, about 17 km/s.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 64; Nov. 197
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  • 70
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    Skylab observations of the coronal structure overlying a type III producing active region (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 63; Sept
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  • 71
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    Radiation transfer through a model sunspot (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A cylindrically symmetric model for a sunspot atmosphere using the similarity principle of Schlueter and Temesvary for the magnetic field configuration is presented. The equations of magnetostatic equilibrium are used, augmented by a radial Evershed flow. The LTE radiative transfer equations for the Stokes vector were solved under a variety of conditions for a ray emerging from a typical penumbral point. The contribution from isolated lines to the broadband circular polarization in sunspot penumbrae is evaluated using a more realistic model sunspot atmosphere than has hitherto been considered. Results indicate that the inclusion of a velocity field along the magnetic field vector is unable to give a net circular polarization of sufficient magnitude, although the variation with the angle between the line-of-sight and the magnetic field vector is in qualitative agreement with observations. The corresponding results for the net linear polarization are satisfactory.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 63; Sept
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  • 72
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    Analysis of X-ray and EUV spectra of solar active regions (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Data acquired by two flights of an array of six Bragg crystal spectrometers on an Aerobee rocket to obtain high spatial and spectral resolution observations of various coronal features at soft X-ray wavelengths (9-23A) were analyzed. The various aspects of the analysis of the X-ray data are described. These observations were coordinated with observations from the experiments on the Apollo Telescope Mount and the various data sets were related to one another. The Appendices contain the published results, abstracts of papers, computer code descriptions and preprints of papers, all produced as a result of this research project.
    Keywords: SOLAR PHYSICS
    Type: NASA-CR-161364
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  • 73
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    Sunspots and the physics of magnetic flux tubes. IX - Umbral dots and longitudinal overstability (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The dynamical properties of the sunspot field and of a column of hot gas confined by such a vertical magnetic field are examined in order to understand the umbral dot within the context of the magnetic sunspot structure. Attention is given to the conditions necessary for gas intrusion, longitudinal as well as convective overstability, the growing modes, and the even mode. With the hypothesis that the subsurface magnetic field of a sunspot splits into many separate flux tubes with field-free gas between, it is suggested that the field-free columns occasionally punch their way up through the overlying magnetic field to the surface, appearing there as the bright, field-free umbral dots. Effects fostering the phenomenon are also discussed, that is, the enhanced temperature of a column of rising gas, the strongly reduced overhead magnetic pressure, and the initiated upward intrusion; these effects are illustrated with examples.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 234
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  • 74
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    A comparison of high-temperature flare models with observations and implications for the low-temperature flare (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: EUV data from the Harvard College Observatory and Naval Research Laboratory instruments on board the Skylab Apollo telescope mount, together with SOLRAD 9 X-ray data, are analyzed in order to empirically deduce the variation of emission measure with temperature in the atmosphere of a number of solar flares. A 'mean' differential emission measure profile Q(T) for a flare is constructed which is then compared with the profile predicted by a number of theoretical models. It is found that realistic flare models must include both conductive and radiative terms in the energy equation, and that hydrodynamic terms may be important at low temperatures. The implications of the results obtained are discussed for flare models in general and it is shown that the inclusion of the conductive term into models which have hitherto neglected it can perhaps resolve some of the observational difficulties with such models.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 232
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  • 75
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    Transient brightenings of interconnecting loops - Morphology of the sudden brightenings (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Sudden brightenings of coronal loops that interconnect active regions are studied. Such brightenings often occur within one or two days after the birth of a new interconnecting loop, as well as in some old interconnections. The brightenings of young loops are obviously associated with the emergence of new magnetic flux near their footpoints, whereas some enhancements of old loops may be triggered by slowly moving disturbances propagating from other centers of activity. A few loop brightenings are associated with flares, but the loop does not brighten in consequence of the energy supply from the flare. Both the flare and the loop brightening are independent consequences of one common agent, presumably newly emerging flux. Temperatures in brightened loops are between 3 and 4 x 10 to the 6th K and densities are less than 2 x 10 to the 9th/cu cm, probably less than 5 x 10 to the 8th/cu cm in some old loops. The top part of a loop is the site of the most intense brightening in the initial phase of a loop enhancement. The most frequent lifetime of these brightenings is 6 to 7 hr.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 63; Sept
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  • 76
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    Collective plasma effects associated with the continuous injection model of solar flare particle streams (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A modified continuous injection model for impulsive solar flares that includes self-consistent plasma nonlinearities based on the concept of marginal stability is presented. A quasi-stationary state is established, composed of a hot truncated electron Maxwellian distribution confined by acoustic turbulence on the top of the loop and energetic electron beams precipitating in the chromosphere. It is shown that the radiation properties of the model are in accordance with observations.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 233
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  • 77
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    Examples of problem flares or situations in past solar-terrestrial observations (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: Instances of solar activity are discussed in terms of their relative interference with making solar terrestrial observations. Unexpected flares of significance are reported and the geophysical effects of these flares are noted.
    Keywords: SOLAR PHYSICS
    Type: NOAA Solar-Terrest. Predictions Proc., Vol. 1; p 385-397
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  • 78
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    Observation of an impulsive solar X-ray burst from a coronal source (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Observations of the spatial, spectral, and temporal structure of an impulsive hard X-ray source in a behind-the-limb solar flare have been made with high-time-resolution hard X-ray detectors aboard two spacecraft, the International Sun Earth Explorer 3 (ISEE 3) and the Pioneer Venus Orbiter (PVO), which were separated in heliographic longitude by about 12.5 deg. The principal findings are that (1) the coronal part of the X-ray source is about 600 times less intense than the lower-altitude part of the source; and (2) the coronal X-ray observations are consistent with a power-law electron spectrum which extends down to about 5 keV.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 233
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  • 79
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    Sunspots and the physics of magnetic flux tubes. VIII - Overstability in a magnetic field in a downdraft (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The dynamical properties of convective overstability in a vertical magnetic field with a downdraft are considered. A variety of effects is illustrated. The overstability produces Alfven waves propagating both upward or downward along the magnetic field. The favored direction of emission may be upward or downward depending upon the magnitude of the heat transport coefficient. The largest asymmetry is produced by a difference in reflectivity between the upper and lower boundaries. It is shown that a very modest reflection coefficient of the upper boundary, with no reflection at the lower boundary, causes most of the waves to be emitted downward, and vice versa. Applying these results to the flux tubes extending up through the convective zone of the Sun, it follows that those flux tubes are dynamically active beneath the surface, as suggested earlier by ourselves and others, but there is no reason to expect any significant wave flux to appear in the field above the surface. The waves propagate downward into the Sun and are presumably dispersed there by the nonlinear interaction with the turbulent convection, etc.
    Keywords: SOLAR PHYSICS
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  • 80
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    Numerical modeling of quasi-static coronal loops. I - Uniform energy input (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A quasi-static numerical model for coronal loops is considered for the case of a uniform energy input per unit volume into the loops. A line dipole model is used to represent the loop magnetic field, and the variations in loop cross section observed in X-ray photographs are parameterized by the ratio between the cross-sectional areas at the loop apex and base. The results of numerical modeling indicate that for an area ratio greater than unity, increases in the area ratio of a loop with a given length and apex area cause a general rise in electron density and a fall in the temperature gradient, leading to large increases in the differential emission factor at high temperatures. The differential function obtained is significantly different from that predicted by analytical models; however, analytical predictions for the temperature-electron density relations are comparable to numerical results. It is also concluded that even a symmetrical loop may have a maximum temperature away from the apex.
    Keywords: SOLAR PHYSICS
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  • 81
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    Stochastic acceleration of solar flare protons (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The acceleration of solar flare protons by the cyclotron damping of intense Alfven wave turbulence in a magnetic trap is considered. The energy diffusion coefficient is computed for a near-isotropic distribution of super-Alfvenic protons, and a steady-state solution for the particle spectrum is found for both transit-time and diffusive losses out of the ends of the trap. The acceleration time to a characteristic energy of about 20 MeV per nucleon can be as short as 10 sec. On the basis of phenomenological arguments, it is inferred that the Alfven wave spectrum typically has an inverse square frequency dependence and that the correlation time of the turbulence lies in the range between 0.5 and 50 msec.
    Keywords: SOLAR PHYSICS
    Type: AD-A081336 , Astrophysical Journal; vol. 233
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  • 82
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    The energy balance and pressure in the solar transition zone for network and active region features (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The electron pressure and energy balance in the solar transition zone are determined for about 125 network and active region features on the basis of high spectral and spatial resolution extreme ultraviolet spectra. Si III line intensity ratios obtained from the Naval Research Laboratory high-resolution telescope and spectrograph during a rocket flight are used as diagnostics of electron density and pressure for solar features near 3.5 x 10 to the 4th K. Observed ratios are compared with the calculated dependence of the 1301 A/1312 A and 1301 A/1296 A line intensity ratios on electron density, temperature and pressure. Electron densities ranging from 2 x 10 to the 10th/cu cm to 10 to the 12th/cu cm and active region pressures from 3 x 10 to the 15th to 10 to the 16th/cu cm K are obtained. Energy balance calculations reveal the balance of the divergence of the conductive flux and turbulent energy dissipation by radiative energy losses in a plane-parallel homogeneous transition zone (fill factor of 1), and an energy source requirement for a cylindrical zone geometry (fill factor less than 0.04).
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 233
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  • 83
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    The magnetospheric electric field and convective processes as diagnostics of the IMF and solar wind (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: Indirect measurements of the convection field as well as direct of the ionospheric electric field provide a means to at least monitor quanitatively solar wind processes. For instance, asymmetries in the ionospheric electric field and ionospheric Hall currents over the polar cap reflect the solar wind sector polarity. A stronger electric field, and thus convective flow, is found on the side of the polar cap where the y component of the IMF is parallel to the y component of the geomagnetic field. Additionally, the magnitude of the electric field and convective southward B sub Z and/or solar wind velocity, and thus may indicate the arrival at Earth of an interaction region in the solar wind. It is apparent that processes associated with the convention electric field may be used to predict large scale features in the solar wind; however, with present empirical knowledge it is not possible to make quantitative predictions of individual solar wind or IMF parameters.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Solar-Terrest. Predictions Proc., Vol. 2; p 375-384
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  • 84
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    Ion sound turbulence in the solar wind (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A stability analysis for ion sound is carried out in order to contribute to clarifying the mechanism of some observed fluctuations, which directly uses detailed measured particle distributions rather than model distributions. Correlation with measured wave activity is satisfactory. Valuable information about the instability mechanism, transport processes, and the accuracy of measured distributions can be obtained by this method. An illustration from Helios 1 data is presented.
    Keywords: SOLAR PHYSICS
    Type: Contrib. to the 4th Solar Wind Conf.; p 1-6
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  • 85
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    The solar wind interaction with Venus (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The Pioneer Venus orbiter reveals that Venus has a well developed bow shock like the Earth's but on that is significantly weaker than the Earth's shock. The location of the bow shock is highly variable, more so than would have been expected for an obstacle of essentially fixed size. The altitude of the ionopause is also highly variable in response to changes in the solar wind. In the ionosphere, the field is often low. However, on some orbits, very large fields are seen as low as 150 km, and on most dayside orbits, thin magnetic structures of flux ropes are observed. At night, large fields are often observed which vary from orbit to orbit. Venus has a much smaller intrinsic magnetic moment than expected from scaling the terrestrial moment.
    Keywords: SOLAR PHYSICS
    Type: ESA Magnetospheric Boundary Layers; p 231-239
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  • 86
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    An empirical polytrope law for solar wind thermal electrons between 0.45 and 4.76 AU: Voyager 2 and Mariner 10 (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Empirical evidence is presented that solar wind thermal electrons obey a polytrope law with polytrope index gamma = 1.175 plus or minus 0.03. The Voyager 2 and Mariner 10 data used as evidence are compared and discussed. The theoretical predictions that solar wind thermal electrons in the asymptotic solar wind should obey a polytrope law with polytrope index gamma = 1.16 plus or minus. The widespread impressions in the literature that solar wind electrons behave more like an isothermal than adiabatic gas, and the arguments that Coulomb collisions are the dominant stochastic process shaping observed electron distribution functions in the solar wind are reexamined, reviewed and evaluated. The assignment of the interplanetary potential as equal to approximately seven times the temperature of the thermal electrons is discussed.
    Keywords: SOLAR PHYSICS
    Type: NASA-TM-80594
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  • 87
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    An interpretation of the polarization of microwave bursts (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: High-spatial-resolution (a few seconds of arc) observations of microwave bursts have demonstrated that only the impulsive phase of the burst is polarized; one observes only one polarity in the burst source if it is weak (Alissandrakis and Kundu) and both polarities if it is intense (Enome et al.). These results are interpreted in terms of an asymmetrical bipolar field structure of the loop in which the energetic electrons responsible for the radiation are contained. The role of unequal field strengths at the feet of the loop on the number of electrons trapped and their pitch angle distribution are discussed in a specific model. Computations of the polarized intensity originating from each foot of the loop seem to be consistent with the observations at present available.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 232
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  • 88
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    Sunspots and the physics of magnetic flux tubes. VI - Convective propulsion. VII - Heat flow in a convective downdraft (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The effect of negative aerodynamic drag in an ideal fluid subject to convective instability is considered. It is shown that a cylinder moving in such a fluid is propelled forward in its motion by the convective forces and that the characteristic acceleration time is comparable to the onset time of convective motions in the fluid. It is suggested that convective propulsion plays an important role in the dynamics of flux tubes extending through the surface of the sun. The suppression of the upward heat flow in a Boussinesq convective cell with free upper and lower boundaries by a downdraft is then analyzed. Application to the solar convection zone indicates that downdrafts of 1 to 2 km/s at depths of 1000 to 4000 km beneath the visible surface of the sun are sufficient to reduce the upward heat flux to a small fraction of the ambient value.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 232
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  • 89
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    EUV observations of quiescent prominences from Skylab (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Measurements of line intensities and line widths for three quiescent prominences observed with Naval Research Laboratory slit spectrograph on ATM/Skylab are reported. The wavelengths of the observed lines cover the range 1175 A to 1960 A. The measured intensities have been calibrated to within approximately a factor 2 and are average intensities over a 2 arcsec by 60 arcsec slit. Nonthermal velocities from the measured line widths are derived. The nonthermal velocity is found to increase with temperature in the prominence transition zone. Electron densities and pressures are derived from density sensitive line ratios. Electron pressures for two of the prominences are found to lie in the range 0.04-0.08 dyn/sq cm, while values for the third and most intense and active of the three prominences are in the range 0.07-0.22 dyn/sq cm.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 61; Mar
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  • 90
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    Average photospheric poloidal and toroidal magnetic field components near solar minimum (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Average (over longitude and time) photospheric magnetic field components are derived from 3-min Stanford magnetograms made near the solar minimum of cycle 21. The average magnetograph signal is found to behave as the projection of a vector for measurements made across the disk. The poloidal field exhibits the familiar dipolar structure near the poles, with a measured signal in the line Fe I 5250 A of about 1 G. At low latitudes the poloidal field has the polarity of the poles, but is of reduced magnitude (about 0.1 G). A net photospheric toroidal field with a broad latitudinal extent is found. The polarity of the toroidal field is opposite in the northern and southern hemispheres and has the same sense as subsurface flux tubes giving rise to active regions of solar cycle 21. These observations are used to discuss large-scale electric currents crossing the photosphere and angular momentum loss to the solar wind.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 61; Mar. 197
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  • 91
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    Sunspots and the physics of magnetic flux tubes. I - The general nature of the sunspot. II - Aerodynamic drag (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Analysis of the dynamical stability of a large flux tube suggests that the field of a sunspot must divide into many separate tubes within the first 1000 km below the surface. Buoyancy of the Wilson depression at the visible surface and probably also a downdraft beneath the sunspot hold the separate tubes in a loose cluster. Convective generation of Alfven waves, which are emitted preferentially downward, cools the tubes. Aerodynamic drag on a slender flux tube stretched vertically across a convective cell is also studied. Since the drag is approximately proportional to the local kinetic energy density, the density stratification weights the drag in favor of the upper layers. Horizontal motions concentrated in the bottom of the convective cell may reverse this density effect. A downdraft of about two km/sec through the flux tubes beneath the sunspot is hypothesized.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 230
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  • 92
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    Solar constant - Constraints on possible variations derived from solar diameter measurements (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Climatically significant variation of the solar constant (the energy output of the sun) implies measurable change in the solar radius. The available data limit variations of the solar radius between 1850 and 1937 to about 0.25 arc second; modeling of the sun indicates that the solar constant did not vary by more than 0.3 percent during that time.
    Keywords: SOLAR PHYSICS
    Type: Science; 204; June 22
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  • 93
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    Activity in the quiet sun. I - Observations of macrospicules in H-alpha and D3 (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 61; Mar. 197
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  • 94
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    The Balmer 9 and Balmer 11 lines of He II in the sun (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The Balmer 9 and 11 lines of He II at 959 A and 942 A in solar spectra are identified. These lines are produced mainly by recombination following photoionization of He II by coronal XUV radiation. From analysis of the line intensities, the theoretical model of Avrett et al. (1976), is confirmed where it was found that an appreciable amount of He (2+) is present at temperatures of 1 - 2 x 10 to the 4th K and that the anomalously strong He II 304 line is produced primarily by collisional excitation. The suggestion of Kohl (1977) that the photoionization-recombination process is more important in active regions than in the quiet sun is confirmed, and we find that the 304-A line is produced largely by recombination in solar flares.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 61; Mar. 197
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  • 95
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    Association of low-frequency waves with suprathermal ions in the upstream solar wind (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Observations obtained upstream of the earth's bowshock with the LASL/MPI plasma instruments and the UCLA magnetometers on ISEE-1 and 2 have revealed a striking relationship between the presence of low-frequency fluctuations in solar wind density and field strength and the different types of distribution functions of upstream ions. Waves are absent when the ions have the beamlike distribution of the 'reflected' ions. Large-amplitude waves are present only in conjunction with the 'diffuse' ions, which are characterized by flat energy spectra and broad angular distributions. The waves are largely compressive, showing very good correlation between oscillations in magnetic field strength and plasma density.
    Keywords: SOLAR PHYSICS
    Type: Geophysical Research Letters; 6; Mar. 197
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  • 96
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    The association of coronal mass ejection transients with other forms of solar activity (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Coronal mass-ejection transients observed with the white-light coronagraph on Skylab are found to be associated with several other forms of solar activity. There is a strong correlation between such mass-ejection transients and chromospheric H-alpha activity, with three-quarters of the transients apparently originating in or near active regions. It is inferred that 40% of transients are associated with flares, 50% are associated with eruptive prominences solely (without flares), and more than 70% are associated with eruptive prominences or filament disappearances (with or without flares). Nine of ten flares that displayed apparent mass ejections of H-alpha-emitting material from the flare site could be associated with coronal transients. Within each class of activity, the more energetic events are more likely to be associated with an observable mass ejection.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 61; Feb. 197
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  • 97
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    Two-dimensional, time-dependent MHD description of interplanetary disturbances Simulation of high speed solar wind interactions (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A two-dimensional, time-dependent nonlinear MHD model is used to simulate the general features of multiply-interacting, transient solar wind flows. The major advantage of the two-dimensional model over the one-dimensional one is the proper consideration of azimuthal gradients. In addition, the new model can provide contour maps for disturbed plasma properties in the equatorial plane, thereby enabling one to perform essential tests of the physical assumptions through direct comparison with space probe data.
    Keywords: SOLAR PHYSICS
    Type: Planetary and Space Science; 27; Mar. 197
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  • 98
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    Observations of solar oscillations with periods of 160 minutes (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Severny et al. (1976) have reported oscillations of the sun with a period near 160 min. A description is presented of observations made at the Stanford Solar Observatory during the time from 1975 to the present which seem to support the reports by Severny et al. At Stanford the relative velocity between a central circular area of radius 0.5 solar radius on the solar disk and most of the remaining area of the solar disk is measured. A superposed epoch analysis of the observations using a period of 160 min is discussed. An apparent agreement in phase between the obtained observational data and those reported by Severny et al. tends to support the interpretation that solar oscillations are being observed.
    Keywords: SOLAR PHYSICS
    Type: Nature; 277; Feb. 22
    Format: text
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    Preflare characteristics of active regions observed in soft X-rays (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: X-ray images from the AS&E telescope on Skylab are used to investigate coronal conditions in solar active regions during the 20-min periods preceding the X-ray onsets of small flares. The preflare or precursor phase is defined as a phase with a characteristic length or time scale significantly different from that of the rise phase. We show that there is no observational evidence of a requirement for a coronal preflare heating phase with a time scale longer than 2 min for small flares characterized by one or two loops. In 18 out of 25 cases the flaring X-ray structure was not the brightest feature in the preflare active region. The electron densities are estimated for preflare loops.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 62; June 197
    Format: text
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  • 100
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    Carbon-poor solar flare events (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A survey of energetic particle flux enhancements over the period from October 1973 to December 1977 has been performed by using the University of Maryland/Max-Planck-Institut ULET sensor on the IMP 8 spacecraft. During the four-year period of the study, it is found that the most extreme periods of Fe enrichment compared with oxygen were during solar flare events in February 1974 and May 1974. In these same events, the carbon abundance with respect to oxygen was significantly depleted when compared with a value C:O of about 0.45:1 for typical solar flares. These observations, taken together with previously reported He-3 enrichment in these events, give strong evidence for the importance of a wave-particle interaction in the preinjection heating of the ambient matter.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 231
    Format: text
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