On the Possibility of Radio Observations of Current Sheets on the Sun

Possibility of a discovery of current sheets in the radioband by using their screening and reflective properties as also their own emission is discussed. It is shown, that the thermal bremsstrahlung of the sheet may be of a sufficiently large intensity on the maximal critical frequency for the plasma in the sheet. In dependence from electron density No and temperature Ts the thickness of the sheet from tens centimetres to hundreds metres is sufficient to provide optical depth Spectral observations with sufficient angular resolution may give such characteristics of the sheet as its temperature, electron density, thickness and height in the solar atmosphere.

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Correlations of solar-flare electron events with radio and X-ray emission from the sun

Canadian Journal of Physics ◽

10.1139/p68-345 ◽

1968 ◽

Vol 46 (10) ◽

pp. S757-S760 ◽

Cited By ~ 7

Author(s):

R. P. Lin

Keyword(s):

Solar Flare ◽

Solar Radio ◽

Interplanetary Space ◽

The Sun ◽

Radio Bursts ◽

Radio Observations ◽

X Ray ◽

Type Iii ◽

Electron Event ◽

Burst Emission

The > 40-keV solar-flare electrons observed by the IMP III and Mariner IV satellites are shown to be closely correlated with solar radio and X-ray burst emission. In particular, intense type III radio bursts are observed to accompany solar electron-event flares. The energies of the electrons, the total number of electrons, and the size of the electron source at the sun can be inferred from radio observations. The characteristics of the electrons observed in interplanetary space are consistent with these radio observations. Therefore these electrons are identified as the exciting agents of the type III emission. It has been noted that the radio and X-ray bursts are part of the flash phase of flares. The observations indicate that a striking feature of the flash phase is the production of electrons of 10–100 keV energies.

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Optical and Radio Observations of Large Scale Magnetic Fields on the Sun

Symposium - International Astronomical Union ◽

10.1017/s007418090002307x ◽

1971 ◽

Vol 43 ◽

pp. 609-615 ◽

Cited By ~ 7

Author(s):

G. Daigne ◽

M. F. Lantos-Jarry ◽

M. Pick

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Large Scale ◽

Interplanetary Medium ◽

Coronal Magnetic Field ◽

The Sun ◽

Radio Observations ◽

Active Centers ◽

Field Patterns

It is possible to deduce information concerning large scale coronal magnetic field patterns from the knowledge of the location of radioburst sources.As the method concerns active centers responsible for corpuscular emission, the knowledge of these structures may have important implications in the understanding of corpuscular propagation in the corona and in the interplanetary medium.

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New remote radio observations of Jupiter by Parker Solar Probe

10.5194/egusphere-egu2020-19055 ◽

2020 ◽

Author(s):

Alain Lecacheux ◽

Stuart D. Bale ◽

Milan Maksimovic ◽

Marc Pulupa

Keyword(s):

Low Frequency ◽

Dynamic Spectrum ◽

Plasma Structure ◽

The Sun ◽

Radio Observations ◽

Inner Magnetosphere ◽

Radio Emissions

The FIELDS/RFS experiment aboard the Parker Solar Probe spacecraft, in orbit around the Sun, is able to detect and remotely study low frequency radio emissions from Jupiter. Accurate measurements of the intensity and polarisation of those emissions (mainly the HOM/DAM components) were obtained throughout years 2018 and 2019. They are compared to similar ones, obtained 20 years ago, during Cassini&#8217;s remote flyby of Jupiter. A particular emphasis is brought on the so-called &#8220;attenuation bands&#8221; phenomenon, - a well-defined intensity extinction/enhancement feature modulating the HOM dynamic spectrum -, which likely results from the radiation propagating to the observer through some permanent or long lived plasma structure (not firmly identified so far) lying in the rotating Jovian inner magnetosphere.

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Formation of current sheets and plasmoids within corotating/stream interaction regions

10.5194/egusphere-egu2020-2102 ◽

2020 ◽

Author(s):

Timofey Sagitov ◽

Roman Kislov

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Coronal Hole ◽

High Speed ◽

Solar Rotation ◽

Coronal Holes ◽

Rotation Period ◽

The Sun ◽

Current Sheets ◽

Interaction Regions

High speed streams originating from coronal holes are long-lived plasma structures that form corotating interaction regions (CIRs) or stream interface regions (SIRs) in the solar wind. The term CIR is used for streams existing for at least one solar rotation period, and the SIR stands for streams with a shorter lifetime. Since the plasma flows from coronal holes quasi-continuously, CIRs/SIRs simultaneously expand and rotate around the Sun, approximately following the Parker spiral shape up to the Earth&#8217;s orbit.Coronal hole streams rotate not only around the Sun but also around their own axis of simmetry, resembling a screw. This effect may occur because of the following mechanisms: (1) the existence of a difference between the solar wind speed at different sides of the stream, (2) twisting of the magnetic field frozen into the plasma, and&#160; (3) a vortex-like motion of the edge of the mothering coronal hole at the Sun. The screw type of the rotation of a CIR/SIR can lead to centrifugal instability if CIR/SIR inner layers have a larger angular velocity than the outer. Furthermore, the rotational plasma movement and the stream distortion can twist magnetic field lines. The latter contributes to the pinch effect in accordance with a well-known criterion of Suydam instability (Newcomb, 1960, doi: 10.1016/0003-4916(60)90023-3). Owing to the presence of a cylindrical current sheet at the boundary of a coronal hole, conditions for tearing instability can also appear at the CIR/SIR boundary. Regardless of their geometry, large scale current sheets are subject to various instabilities generating plasmoids. Altogether, these effects can lead to the formation of a turbulent region within CIRs/SIRs, making them filled with current sheets and plasmoids.&#160;We study a substructure of CIRs/SIRs, characteristics of their rotation in the solar wind, and give qualitative estimations of possible mechanisms which lead to splitting of the leading edge a coronal hole flow and consequent formation of current sheets within CIRs/SIRs.

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A Three-dimensional Study of Reconnection, Current Sheets, and Jets Resulting from Magnetic Flux Emergence in the Sun

The Astrophysical Journal ◽

10.1086/427872 ◽

2004 ◽

Vol 618 (2) ◽

pp. L153-L156 ◽

Cited By ~ 60

Author(s):

K. Galsgaard ◽

F. Moreno-Insertis ◽

V. Archontis ◽

A. Hood

Keyword(s):

Magnetic Flux ◽

Three Dimensional ◽

The Sun ◽

Flux Emergence ◽

Current Sheets

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Solar Radio Observations at 843 MHz

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000023171 ◽

1989 ◽

Vol 8 (2) ◽

pp. 142-144 ◽

Cited By ~ 1

Author(s):

A. D. Gray ◽

D. Campbell-Wilson ◽

M. I. Large

Keyword(s):

Solar Radio ◽

Coronal Holes ◽

Total Power ◽

The Sun ◽

Two Dimensional ◽

Radio Observations ◽

Radio Brightness ◽

Partial Synthesis ◽

One Dimensional ◽

Exact Relationship

AbstractThe Molonglo Observatory Synthesis Telescope (MOST) has been used to observe the Sun with total-power fan-beams having a one-dimensional resolution of 41 arcsec at 843 MHz. The scans reveal clearly the rotation and evolution of the slowly-varying component as well as some burst activity. Low radio brightness features have also been identified, but the exact relationship between these features and coronal holes is, as yet, unclear. Several partial synthesis observations have been used to generate two-dimensional radioheliograms.

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Solar and Stellar Magnetic Fields and Atmospheric Structures: Theory

International Astronomical Union Colloquium ◽

10.1017/s0252921100031936 ◽

1989 ◽

Vol 104 (1) ◽

pp. 271-288

Author(s):

E. N. Parker

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Dynamical Behavior ◽

Convective Zone ◽

Coronal Heating ◽

The Sun ◽

Current Sheets ◽

Spontaneous Formation ◽

Stellar Magnetic Fields ◽

The Magnetic Field

AbstractThis presentation reviews selected ideas on the origin of the magnetic field of the Sun, the dynamical behavior of the azimuthal field in the convective zone, the fibril state of the field at the photosphere, the formation of sunspots, prominences, the spontaneous formation of current sheets in the bipolar field above the surface of the Sun, coronal heating, and flares.

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Clark Lake Radio Observations of Coronal Mass Ejections

Symposium - International Astronomical Union ◽

10.1017/s0074180900088501 ◽

1990 ◽

Vol 142 ◽

pp. 495-500

Author(s):

N. Gopalswamy

Keyword(s):

White Light ◽

Coronal Mass Ejections ◽

The Sun ◽

Type Ii ◽

Radio Observations ◽

Magnetic Structures ◽

Effect Relationship ◽

Positional Analysis ◽

Type Iv ◽

Nonthermal Particles

We review some recent studies of mass ejections from the Sun using 2-D imaging observations of the Clark Lake multifrequency radioheliograph. Radio signatures of both fast and slow coronal mass ejections (CMEs) have been observed using the Clark Lake radioheliograph. Using temporal and positional analysis of moving type IV and type II bursts, and white light CMEs we find that the type II's and CMEs need not have a direct cause and effect relationship. Instead, the type II seems to be generated by a “decoupled shock”, probably due to an associated flare. The moving type IV burst requires nonthermal particles trapped in magnetic structures associated with the CME. Since nonthermal particles can be generated independent of the speed of CMEs, moving type IV bursts need not be associated only with fast CMEs. Specific examples are presented to support these views.

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