Long Time Statistics of Magnetically Driven MHD Turbulence, Solar Flares and Coronal Heating

1996 ◽  
pp. 45-46
Author(s):  
C. Chiuderi ◽  
M. Velli ◽  
G. Einaudi ◽  
A. Pouquet
Keyword(s):  
Solar Flares ◽  
Coronal Heating ◽  
Mhd Turbulence ◽  
Long Time

Non-Gaussian probability distributions of solar wind fluctuations

1994 ◽  
Vol 12 (12) ◽  
pp. 1127-1138 ◽  
Author(s):  
E. Marsch ◽  
C. Y. Tu
Keyword(s):  
Solar Wind ◽  
Probability Distributions ◽  
Time Lag ◽  
Small Scale ◽  
Time Lags ◽  
Mhd Turbulence ◽  
Theoretical Concepts ◽  
Fluid Turbulence ◽  
Long Time ◽  
Non Gaussian

Abstract. The probability distributions of field differences ∆x(τ)=x(t+τ)-x(t), where the variable x(t) may denote any solar wind scalar field or vector field component at time t, have been calculated from time series of Helios data obtained in 1976 at heliocentric distances near 0.3 AU. It is found that for comparatively long time lag τ, ranging from a few hours to 1 day, the differences are normally distributed according to a Gaussian. For shorter time lags, of less than ten minutes, significant changes in shape are observed. The distributions are often spikier and narrower than the equivalent Gaussian distribution with the same standard deviation, and they are enhanced for large, reduced for intermediate and enhanced for very small values of ∆x. This result is in accordance with fluid observations and numerical simulations. Hence statistical properties are dominated at small scale τ by large fluctuation amplitudes that are sparsely distributed, which is direct evidence for spatial intermittency of the fluctuations. This is in agreement with results from earlier analyses of the structure functions of ∆x. The non-Gaussian features are differently developed for the various types of fluctuations. The relevance of these observations to the interpretation and understanding of the nature of solar wind magnetohydrodynamic (MHD) turbulence is pointed out, and contact is made with existing theoretical concepts of intermittency in fluid turbulence.

scholarly journals Coronal Heating, Weak MHD Turbulence, and Scaling Laws

2007 ◽  
Vol 657 (1) ◽  
pp. L47-L51 ◽  
Author(s):  
A. F. Rappazzo ◽  
M. Velli ◽  
G. Einaudi ◽  
R. B. Dahlburg
Keyword(s):  
Scaling Laws ◽  
Coronal Heating ◽  
Mhd Turbulence

scholarly journals Tidal Force of Sun Due to Planetary Radial Alignment and Sun-Spot Cycle

1993 ◽  
Vol 132 ◽  
pp. 407-414
Author(s):  
S.D. Verma
Keyword(s):  
Sunspot Number ◽  
Solar Flares ◽  
Tidal Force ◽  
Solar Photosphere ◽  
Neutral Atmosphere ◽  
The Sun ◽  
Cycle Number ◽  
Long Time ◽  
Small Force ◽  
Periodic Changes

AbstractIt is well known that the Sun’s radiation and a large number of phenomena occurring on the sun have influence on the Earth’s near environment i.e. Atmosphere, Ionosphere, Magnetosphere, etc. These manifest themselves as day-night, seasons, tides and many changes in the neutral atmosphere; changes in meteorological parameters. These changes are directly or indirectly related to variations in solar parameters, such as solar flares, magnetic storms, variations in sunspot number occurring in solar photosphere. Sunsports are observed, their number counted and their accurate records maintained for long time (many centuaries). The sunspot number seems to follow periodic changes with several periods; mainly 11 years and 23.5 years. Recently it has been shown that the combined tidal force of the inner planets and two largest planets, Jupiter and Saturn, have periodic change of 11 and 23.5 years. It was proposed that this small force may be having a tiny influence on the surface of the Sun and causing some nonlinear effect which results into formation of sunspots and thus causes the variations in the number of sunspots. In the present work it is shown that whenever the combined tidal force on sun increases then sunspot number seems to increase and when force decreases sunspot number decreases. This is shown for Solar Cycle number 21.

scholarly journals Turbulent Acceleration in Solar Flares

1994 ◽  
Vol 142 ◽  
pp. 623-630
Author(s):  
D. B. Melrose
Keyword(s):  
Solar Flares ◽  
Gamma Ray ◽  
Low Frequency ◽  
Impulsive Phase ◽  
Primary Energy ◽  
Nonthermal Electron ◽  
Relativistic Electrons ◽  
Mhd Turbulence ◽  
Narrow Channels ◽  
Current Instability

AbstractTurbulent acceleration in the impulsive phase of solar flares is reviewed, with the emphasis on bulk energization of nonrelativistic electrons and prompt acceleration of the gamma-ray emitting nonrelativistic ions and relativistic electrons. The primary energy release in a flare cannot be due to collisional dissipation. Anomalous resistivity requires that the current flows in many narrow channels with the current density above threshold for current instability. The bulk energization of the electrons is due to the damping of low-frequency electrostatic turbulence generated by the current instability. This turbulence also limits the rate a nonthermal electron tail forms due to runaway acceleration. Stochastic and gyroresonant acceleration by MHD turbulence are discussed briefly, emphasizing the need for preacceleration. Stochastic acceleration is favorable for the gamma-ray emitting particles only if an adequated source of the MHD turbulence can be identified.Subject headings: acceleration of particles — MHD — Sun: flares — turbulence

LATTICE MODELS FOR SOLAR FLARES AND CORONAL HEATING

2006 ◽  
Vol 2 (S233) ◽  
pp. 481
Author(s):  
O. Podladchikova ◽  
B. Lefebvre
Keyword(s):  
Solar Flares ◽  
Lattice Models ◽  
Coronal Heating

Geometric Effects in Avalanche Models of Solar Flares: Implications for Coronal Heating

2001 ◽  
Vol 563 (2) ◽  
pp. L165-L168 ◽  
Author(s):  
S. W. McIntosh ◽  
P. Charbonneau
Keyword(s):  
Solar Flares ◽  
Coronal Heating ◽  
Geometric Effects ◽  
Avalanche Models

Recent progress made in numerical experiments on magnetic reconnection and the related solar activities 

2021 ◽  
Author(s):  
Jun Lin ◽  
Jing Ye
Keyword(s):  
Magnetic Reconnection ◽  
Solar Flares ◽  
Numerical Experiments ◽  
Recent Progress ◽  
Magnetic Energy ◽  
Solar Physics ◽  
Plasma Heating ◽  
Mhd Turbulence ◽  
2D And 3D ◽  
Made In

<p>Magnetic reconnection plays a crucial role in the process of solar flares and coronal mass ejections, in which large amounts of magnetic energy (10^29-10^32 ergs) are converted into kinetic energy and thermal energy, even allowing for particle acceleration. On the platform of the Computational Solar Physics Laboratory of Yunnan Observatories, we have performed a series of numerical experiments on magnetic reconnection related to solar eruption events as well as numerical method developments both in 2D and 3D. In this talk, we will present some recent studies on the topic of plasma heating by reconnection, MHD turbulence, wave structures and complicate structures of CMEs, etc. Our numerical results have great potentials to explain and predict many related solar activities in the corona. </p>

STATISTICAL PROPERTIES OF SOLAR FLARES AND COMPARISON TO OTHER IMPULSIVE ENERGY RELEASE EVENTS

2009 ◽  
Vol 23 (28n29) ◽  
pp. 5609-5618 ◽  
Author(s):  
FABIO LEPRETI ◽  
VLADIMIR G. KOSSOBOKOV ◽  
VINCENZO CARBONE
Keyword(s):  
Solar Flare ◽  
Energy Release ◽  
Solar Flares ◽  
Statistical Properties ◽  
Universal Curve ◽  
Mhd Turbulence ◽  
Natural Systems ◽  
Self Organized ◽  
Self Organized Criticality ◽  
Impulsive Processes

Impulsive energy release events are observed in many natural systems. Solar flares are certainly among the most remarkable examples of such processes. In the last years the study of solar flare statistical properties has received considerable attention in the context of solar flare models based on different approaches, such as Self Organized Criticality (SOC) or magnetohydrodynamic (MHD) turbulence. In this talk the main statistical properties of solar flares will be presented and compared to those of other well known impulsive processes, such as earthquakes and soft γ-ray flashes occurring on neutron stars. It is shown that the these phenomena are characterized by different statistics that cannot be rescaled onto a single, universal curve and that this holds even for the same phenomenon, when observed in different periods or at different locations. Our results indicate apparent complexity of impulsive energy release processes, which neither follow a common behavior nor could be attributed to a universal physical mechanism.

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