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N91-10828# National Center for Atmospheric Research, Boulder,
Prepared in cooperation with Sydney Univ., Australia (Grant NSF ATM-87-09659) (PB90-214487; NCAR/CT-124) Avail: NTIS HC/MF A15 CSCL 03B
Observations of Stokes spectral profiles enable the magnetic fields on the Sun's surface to be determined. Inversion is the process whereby the profiles are reduced to magnetic field vectors. One of the most robust, accurate, and rapid methods available for inversion uses the least squares fitting of analytical Stokes profiles. As this technique is suitable for the automated reduction of large sets of data, it was adopted for use with the Advanced Stokes Polarimeter, presently under development. The limitations of inversion by analytical profile fitting were not firmly established. Confident analysis of magnet field vectors depends upon the precise interpretation of reduced data. A framework is introduced which allows such an assessment to be made. The magnetofluid-static sunspon models presented provide a self-consistent range of physical conditions similar to those in sunspots. Inversion can then be carried out on Stokes profiles synthesized from these known realistic conditions.
and T. Tajima Aug. 1990 18 p
Effects of strong and random inhomogeneities of the magnetic fields, plasma density, and temperature in the solar atmosphere on the properties of magnetoacoustic waves of arbitrary amplitudes are studied. The procedure which allows one to obtain the averaged equation containing the nonlinearity of a wave, dispersion properties of a system, and dissipative effects is described. It is shown that depending on the statistical properties of the medium, different scenarios of wave propagation arise: in the predominance of dissipative effects the primary wave is damped away in the linear stage and the efficiency of heating due to inhomogeneities is much greater than that in homogeneous medium. Depending on the interplay of nonlinear and dispersion effects, the process of heating can be afforded through the formation of shocks or through the storing of energy in a system of solitons which are later damped away. Our computer simulation supports and extends the above theoretical investigations. In particular the enhanced dissipation of waves due to the strong and random inhomogeneities is observed and this is more pronounced for shorter waves.
N91-10829*# Jet Propulsion Lab., California Inst. of Tech.,
(Contract NAS7-918) (NASA-CR-187337; JPL-Publ-90-34; NAS 1.26:187337) Avail: NTIS HC/MF A03 CSCL 03B
Solar radio emission could seriously interfere with observations made by a low frequency (1 to 10 MHz) array in space. International Sun-Earth Explorer (ISEE-3) radio data were used to determine solar emission level. The results indicate that solar emission should seriously disturb less than ten percent of the data, even during the years of solar maximum. Thus it appears that solar emission should not cause a disastrous loss of data. The information needed to design procedures to excise solar interference from the data produced by any low-frequency array is provided.
N91-10832*# National Aeronautics and Space Administration.
The objective was to develop the capability for and coaligned observations of the structure and evolution of the Sun's magnetic field at two different heights in the solar atmosphere: the photosphere, which is the lowest region observable with optical telescopes; and the chromosphere, which lies just above the photosphere and is the region where the magnetic field dominates the gas motion so that a well-ordered structure governed by the field is observed. By obtaining this three-dimensional picture of the solar magnetic field, a better understanding can be developed of the magnetic forces that produce and control the dynamic, high-energy phenomena occurring in the solar atmosphere that can affect the entire heliosphere, including the terrestrial environment.
N91-10830# Lawrence Livermore National Lab., CA. CORONAL HEATING BY NANOFLARES: PLASMA DYNAMICS OF ELEMENTARY EVENTS Roger A. Kopp and Giannina Poletto (Osservatorio Astrofisico di Arcetri, Florence, Italy) 1990 4 p Presented at the Mechanisms of Chromospheric and Coronal Heating, Heidelberg, Fed. Republic of Germany, 5-8 Jun. 1990 Sponsored in part by Consiglio Nazionale delle Richerche; Florence Univ, Italy; and Italian Space Agency (Contract W-7405-eng-36) (DE90-016495; LA-UR-90-2764; CONF-9006261-1) Avail: NTIS HC/MF A01
It has been suggested by Parker Sturrock et al., and others that the corona may be stochastically heated, on spatial scales at or below current instrumental resolution limits, by a continuous succession of many small flarelike events commonly referred to as nanoflares. In this paper we extend a semi-analytical point model developed previously for solar compact flares, to include gravitational plasma downfall during the late decay phase. Applying the model to conditions representative of nanoflares allows us to predict the temporal variation of average plasma properties in such events and should ultimately facilitate a calculation of the spectral characteristics of a nanoflare-heated corona. DOE
N91-10833# Consiglio Nazionale delle Ricerche, Rome (Italy).
The preliminary five minute pressure corrected data of total neutron intensity and of the intensities of multiplicities one to greater than or equal to eight are presented in the form of daily plots. The data was recorded during March 1990 by the Rome 17-NM-64. Ways in which the data can be used during the forthcoming solar activity maximum are discussed. For each monitor section the various multiplicities are measured in a gate time of 1200 microseconds. The attenuation coefficients for atmospheric pressure change correction are given.
N91-10831# Texas Univ., Austin.
N91-10834# Consiglio Nazionale delle Ricerche, Rome (Italy).
The preliminary five minute pressure corrected data of total neutron intensity and of the intensities of multiplicities one to greater than or equal to eight are presented in the form of daily plots. The data was recorded during April 1990 by the Rome 17-NM-64. Ways in which this data could be used during the forthcoming solar activity maximum are discussed. For each monitor section the various multiplicities are measured in a gate time of 1200 microseconds. The attenuation coefficients for atmospheric pressure change correction are given.
(DE90-016467; LA-UR-90-2631; CONF-900367-2) Avail: NTIS HC/MF A03
Intrinsic properties of neutrinos as deduced from cosmological, astrophysical, and laboratory experiments are reviewed. Bounds on magnetic moments and theoretical models which yield large moments but small masses are briefly discussed. The MSW solution to the solar neutrino problem is reviewed in light of the existing data from the Cl-37 and Kamiokande Il experiments. The combined data disfavor the adiabatic solution and tend to support either the large angle solution or the nonadiabatic one. In the former case the Ga-71 signal will be suppressed by the same factor as for Cl-37, and in the latter case the suppression factor could be as large as 10 or more.
N91-10433# Ceskoslovenska Akademie Ved, Ondrejov.
93 SPACE RADIATION
N91-10837# Consiglio Nazionale delle Ricerche, Rome (Italy). Ist. di Fisica dello Spazio Interplanetario. ON THE AUTOREGRESSION METHODS APPLIED TO THE HOURLY NUCLEONIC-COMPONENT RECORDS S. Pase, M. Parisi, S. Sparnocchia (Rome Univ., Italy ), E. Salusti, and M. Storini Frascati, Italy Oct. 1989 29 p (IFSI-89-19; ETN-90-97780) Avail: NTIS HC/MF A03
Application of autoregressive methods to temporal variations of the cosmic ray nucleonic component is presented. The hourly data registered in Rome (Italy) in the NM-64 detector with a threshold rigidity of 6.2 GV during the period 1977 to 1982 is examined. The results obtained through analysis of two Forbush decreases are discussed in detail. These events on February 14, 1978 and July 10, 1982 are shown to be best analyzed using a nonlinear autoregressive model rather than a linear model. The decrease amplitude and temporal recovery phase are easily reconstructed without the aid of external physical parameters.
Includes cosmic radiation; and inner and outer earth's radiation belts.
For biological effects of radiation see 52 Aerospace Medicine. For theory see 73 Nuclear and High-Energy Physics.
N91-10835 Manchester Univ. (England).
The radio properties of a complete sample of 94 core-dominated radio sources, observed with the VLA, are examined to determine whether these properties are consistent with the hypothesis, known as the unified scheme, that core-dominated quasars are intrinsically the same object as lobe-dominated quasars, but just viewed with their radio jets oriented closer to the line of sight. High dynamic range maps are produced by combining data sets from different VLA arrays, frequencies and epochs. Various distributions of parameters are compared with the predictions of the relativistic beaming models. In particular it is found that the data cannot be fitted with a single relativistic jet velocity but require a large dispersion in this parameter. This dispersion only agrees with VLBI data on transverse motions if Hubble's constant is nearer to 100 than 50 km s(exp-1) Mpc(exp-1). Furthermore the large projected linear sizes of the quasars cannot be explained by large intrinsic bend angles but require that these sources have large intrinsic linear sizes. Evidence is also found from the radio properties of the BL Lacs in the sample that they are not quasars oriented with their radio jets at very small angles to the line of sight, as has been proposed by various authors. The radio morphology and spectra of the empty field sources indicate that they may belong to the 'compact VLBI double class of radio source. Finally published optical and x-ray data on quasars are examined and evidence is found for the existence of a beamed component in radio sources which exhibits itself in all wavebands from the radio to the x-ray regime. The presence of such a component has obvious repercussions for understanding of Active Galactic Nuclei.
N91-10838# Consiglio Nazionale delle Ricerche, Rome (Italy).
Data obtained in Chile with the standard neutron monitor are reported. The Santiago 6NM-64 monitor has a geomagnetic cut-off rigidity of about 11 GV. A ground-level solar cosmic ray event registered on September 29, 1989 is analyzed in detail. Possible studies connected with such a rare event are suggested. The importance of such studies in developing a better understanding of solar-interplanetary-terrestrial relations is stressed. Comparisons between the readings recorded at the Rome and Japan based stations are presented.
No abstracts in this category.
N91-10836# Los Alamos National Lab., NM.
Scientific and Technical Aerospace Reports (STAR) is an abstract journal that provides comprehensive coverage of worldwide aerospace-related reports. It is a major product of the International Aerospace Database managed by the NASA Scientific and Technical Information (STI) Program. The coverage includes reports on aeronautics, space, and supporting disciplines. STAR lists current, publicly available reports entered into the NASA STI Database during the 2-week period preceding publication. An explanation of items that appear in each citation is given on the last page of each volume. NASA sponsors a companion journal, International Aerospace Abstracts (IAA), that lists abstracts of the open literature on aerospace subjects available worldwide. IAA is available through the American Institute of Aeronautics and Astronautics. Entries found in STAR and IAA are available through NASA's online service, RECON, as the International Aerospace Database and through DIALOG as the Aerospace Database. Information on aerospace and related subjects is gathered by the NASA STI Program through national and international agreements and exchanges and is made available to the NASA community as well as to the public in many forms through various outlets. The section on NASA STI Program Products and Services contains additional information.
US ISSN 0036-8741