scholarly journals Electron density in the solar corona from type III radio bursts

2020 ◽  
pp. 17-24
Author(s):  
Batbayar Batmunkh ◽  
Batmunkh Damdin
Keyword(s):  
Solar Corona ◽  
Electron Density ◽  
Scale Height ◽  
Frequency Drift ◽  
Radio Bursts ◽  
Empirical Formulas ◽  
Lower Corona ◽  
Type Iii ◽  
Calculation Results ◽  
Good Agreement

It has been proven that electron density in the solar corona is determined by observing the frequency drift of type III radio bursts. We investigated the certain dependence of the scale height on the distance, which allows us to obtain different dependence of the frequency drift rate (FDR) on the frequency. The scale height is presented in a combination of two distance dependencies as H= αλT+(1-α)f(r). As a result of integration of equation, we obtain the electron density ne(r) in the form ne= n0(1+y)((-1) ⁄ ((1-α)b)),  y=((1-α)/(α)) b ((r)/(λT) and the constants are determined in comparison with the empirical formulas for FDR. In particular, using the well-known empirical formula (dν)/(dt)=-0.01ν1.84, we can obtain (1-α)b=0.42. The obtained calculation results are compared with the results of other authors and they have been found to be consistent when choosing the parameters included in the formula. The calculation shows that this formula is in good agreement with the data at distances from the lower corona to the Earth's orbit. This dependence of electron density makes it possible to agree with the observed FDR as a function of frequency.

Solar Type III radio bursts at Saturn’s orbit: Case study of stereoscopic observations by Cassini/RPWS and Wind/WAVES experiments

2020 ◽  
Author(s):  
Ahmed Abou el-Fadl ◽  
Mohammed Boudjada ◽  
Patrick H.M. Galopeau ◽  
Muhamed Hammoud ◽  
Helmut Lammer
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
Electron Density ◽  
Interplanetary Medium ◽  
Wind Waves ◽  
Radio Bursts ◽  
Type Iii ◽  
Source Regions ◽  
Solar Bursts ◽  
Cassini Spacecraft

<p>Type III radio bursts are produced by electron beams accelerated in active regions and following open magnetic field lines. Type III observed frequency is found to be nearly equal to the plasma frequency directly linked to the local electron density. The source regions of such solar bursts are the solar corona and the interplanetary medium where, respectively, higher and lower frequencies are generated. In this work, we consider specific Type III solar bursts simultaneously observed by Cassini/RPWS and Wind/WAVES experiments. Despite the distance of Cassini spacecraft to the Sun such Type III bursts have been detected at Saturn’s orbit, i.e. at about 10AU. Those considered bursts are covering a frequency bandwidth from about 10 MHz down to 100 kHz. We attempt in this study to characterize the spectral pattern, i.e. the flux density versus the observation time and the frequency range, and the visibility of the source regions to the observer (i.e. Wind and Cassini spacecraft). In this context, we analyze the evolution of the Type III bursts from the solar corona and up to Saturn’s orbit taking into consideration the Archimedean spiral which is the geometrical configuration of the solar magnetic field extension in the interplanetary medium. We principally discuss the physical parameters, i.e. solar wind speed and the electron density, which lead to constraint the location of the source region and its visibility to both spacecraft.</p>

scholarly journals The Speed and Acceleration of the Sources of Type III And Type V Solar Radio Bursts Over Large Distances in the Corona

1965 ◽  
Vol 18 (1) ◽  
pp. 67 ◽  
Author(s):  
RT Stewart
Keyword(s):  
Active Region ◽  
Solar Radio ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Mean Velocity ◽  
Lower Corona ◽  
Type Iii ◽  
If Current ◽  
The Mean ◽  
Type V

The outward velocity and acceleration through the solar corona of the disturbances responsible for the emission of 50 type III bursts recorded on the Dapto radio spectrograph are investigated by applying standard electron density models for the corona to the frequency drift of each burst. If current models for an active region are assumed, the velocities often remain unchanged from the lower corona out to heights of at least two solar radii above the photosphere. The mean velocity is about ie. Speeds of sources of type III bursts followed by type V continuum are similar to those for isolated type III bursts.

Nonrelativistic electron beam expansion in the solar corona/wind  and their type III radio bursts observed with LOFAR

2021 ◽  
Author(s):  
Hamish Reid ◽  
Eduard Kontar
Keyword(s):  
Electron Beam ◽  
Energy Density ◽  
Solar Corona ◽  
Electron Beams ◽  
Low Frequency ◽  
High Energy ◽  
High Energy Density ◽  
Moderate Intensity ◽  
Radio Bursts ◽  
Type Iii

<div> <div><span>Solar type III radio bursts contain a wealth of information about the dynamics of near-relativistic electron beams in the solar corona and the inner heliosphere; this information is currently unobtainable through other means.  Whilst electron beams expand along their trajectory, the motion of different regions of an electron beam (front, middle, and back) had never been systematically analysed before.  Using LOw Frequency ARray (LOFAR) observations between 30-70 MHz of type III radio bursts, and kinetic simulations of electron beams producing derived type III radio brightness temperatures, we explored the expansion as electrons propagate away from the Sun.  From relatively moderate intensity type III bursts, we found mean electron beam speeds for the front, middle and back of 0.2, 0.17 and 0.15 c, respectively.  Simulations demonstrated that the electron beam energy density, controlled by the initial beam density and energy distribution have a significant effect on the beam speeds, with high energy density beams reaching front and back velocities of 0.7 and 0.35 c, respectively.  Both observations and simulations found that higher inferred velocities correlated with shorter FWHM durations of radio emission at individual frequencies.  Our radial predictions of electron beam speed and expansion can be tested by the upcoming in situ electron beam measurements made by Solar Orbiter and Parker Solar Probe.</span></div> </div>

scholarly journals The Behaviour of the Outer Solar Corona (3R⊙to 10R⊙) During a Large Solar Flare Observed from OSO-7 in White Light

1974 ◽  
Vol 57 ◽  
pp. 333-334
Author(s):  
G. E. Brueckner
Keyword(s):  
Solar Corona ◽  
Naval Research ◽  
Plasma Cloud ◽  
The Sun ◽  
Radio Bursts ◽  
Type Ii ◽  
Coronal Streamer ◽  
East Limb ◽  
Discrete Type ◽  
Good Agreement

(Solar Phys.). A very bright coronal streamer was observed on December 13, 1971 by the Naval Research Laboratory's coronagraph on board of OSO-7. The next day, the streamer had changed it's brightness and configuration considerably. Three subsequent coronagraph images, taken on December 14 at 0407, 0418 and 0430 UT show a large plasma cloud moving outward from the Sun between 3 and 10 solar radii. They also show distinct smaller clouds moving outward with projected velocities between 950 and 1100 km s−1. Traced back in time to the lower solar corona, these clouds coincide with discrete type II radiobursts observed from Culgoora between 0241 and 0256 UT. Each single cloud shows it's signature in the radio recording between 100 and 20 MHz. The drift velocity of the radio bursts can be determined to be 1600 km s−1using Newkirk's coronal streamer model. Assuming, that the plasma clouds are ejected from an active region 30° behind the east limb vertically, their true velocities close to the surface of the Sun would be approximately 1400 km s−1, which is in good agreement with the drift velocities determined from the type II bursts, considering all uncertainties. Therefore, the type II burst disturbance moves with the same velocity as the driving material.

scholarly journals On the Propagation of the Electrons Related to Type III Bursts

1980 ◽  
Vol 86 ◽  
pp. 327-327 ◽  
Author(s):  
G.V. de Genouillac ◽  
D.F. Escande
Keyword(s):  
Solar Corona ◽  
Electromagnetic Waves ◽  
Solar Radio ◽  
Interplanetary Medium ◽  
Electron Plasma ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Plasma Oscillations ◽  
Type Iii ◽  
Electron Clouds

Type III solar radio bursts are known to be excited by solar electron clouds travelling outwards through the solar corona and interplanetary medium. According to the “plasma hypothesis”, electron plasma oscillations are created by the passing beam, which are in turn converted into electromagnetic waves.

Partition Coefficients of Methylated DNA Bases Obtained from Free Energy Calculations with Molecular Electron Density Derived Atomic Charges.

2018 ◽  
Author(s):  
Alejandro Lara ◽  
Maximiliano Riquelme ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Electron Density ◽  
Partition Coefficients ◽  
Dna Bases ◽  
Atomic Charges ◽  
Free Energies ◽  
Solvation Model ◽  
Minimal Basis ◽  
Methylated Dna ◽  
Implicit Solvation Model ◽  
Good Agreement

<div> <div> <div> <p>Partition coefficients serve in various areas as pharmacology and environmental sciences to predict the hydrophobicity of different substances. Recently, they have been also used to address the accuracy of force fields for various organic compounds and specifically the methylated DNA bases. In this study atomic charges were derived by different partitioning methods (Hirshfeld and Minimal Basis Iterative Stockholder) directly from the electron density obtained by electronic structure calculations in vac- uum, with an implicit solvation model or with explicit solvation taking the dynamics of the solute and the solvent into account. To test the ability of these charges to describe electrostatic interactions in force fields for condensed phases the original atomic charges of the AMBER99 force field were replaced with the new atomic charges and combined with different solvent models to obtain the hydration and chloroform solvation free energies by molecular dynamics simulations. Chloroform-water partition coefficients derived from the obtained free energies were compared to experimental and previously reported values obtained with the GAFF or the AMBER-99 force field. The results show that good agreement with experimental data is obtained when the polarization of the electron density by the solvent has been taken into account deriving the atomic charges of polar DNA bases and when the energy needed to polarize the electron den- sity of the solute has been considered in the transfer free energy. These results were further confirmed by hydration free energies of polar and aromatic amino acid side chain analogues. Comparison of the two partitioning methods Hirsheld-I and Minimal Basis Iterative Stockholder (MBIS) revealed some deficiencies in the Hirshfeld-I method related to nonexistent isolated anionic nitrogen pro-atoms used in the method. Hydration free energies and partitioning coefficients obtained with atomic charges from the MBIS partitioning method accounting for polarization by the implicit solvation model are in good agreement with the experimental values. </p> </div> </div> </div>

Immunological Determined Plasminogen Groups And Its Possible Biological Relevance

1981 ◽  
Author(s):  
V Sachs ◽  
R Dörner ◽  
E Szirmai
Keyword(s):  
Human Plasma ◽  
Type I ◽  
Type Ii ◽  
Precipitation Line ◽  
Gene Frequencies ◽  
Type Iii ◽  
Different Types ◽  
Human Plasminogen ◽  
Gel Diffusion ◽  
Good Agreement

Anti human plasminogen sera of the rabbit precipitate human plasma in the agar gel diffusion test by means of intra-basin absorption with plasminogenfree human plasma with three different types: type I is represented by one strong precipitation line, type II by two lines, a big one and a small one, and type III by three slight but distinct lines. The following frequencies of the different types have been observed in a sample of 516 human plasmas: type I 65%, type II 33% and type III 2%. Suppose the types are phenotypical groups of a diallelic system where the types I and III represent the homozygous genotypes and the type II the heterozygous the estimated gene frequencies are in good agreement with the expected values. There is also a good agreement of the distribution of plasminogen groups determined by electrofocussing from RAUM et al. and HOBART. The plasminogen groups possibly may have also a biological meaning because the plasmas of type III always have a lesser fibrinolytic activity than the plasmas of the other types.

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