Modeling of solar magnetic field using the kinematic-gravitational ion dynamo model

Abstract In present article the kinematic-gravitational ion dynamo model accounting for influence of tidal forces on electric currents in ionized substances is applied to modeling of the magnetic field of the Sun. Estimates of currents and field values obtained using a seven-layer model indicate that tidal forces influence is not insignificant. A correlation method for assessment of the Sun’s polarity was created and applied for a detailed analysis of the polarity of magnetic field of the Sun in the 21 and 22 cycles.

Download Full-text

Solar and Stellar Dynamo Waves Under Asymptotic Investigation

International Astronomical Union Colloquium ◽

10.1017/s0252921100048028 ◽

1998 ◽

Vol 167 ◽

pp. 415-418

Author(s):

Kirill M. Kuzanyan

Keyword(s):

Magnetic Field ◽

Temporal Distribution ◽

Active Regions ◽

Magnetic Activity ◽

Dynamo Model ◽

The Sun ◽

Asymptotic Investigation ◽

Spatio Temporal ◽

Dynamo Wave ◽

The Magnetic Field

AbstractThe main magnetic activity of the Sun can be visualised by Maunder butterfly diagrams which represent the spatio-temporal distribution of sunspots. Besides sunspots there are other tracers of magnetic activity, like filaments and active regions, which are observable over a wider latitudinal range of the Sun. Both these phenomena allow one to consider a complete picture of solar magnetic activity, which should be explained in the framework of one relatively simple model.A kinematic αѡ-dynamo model of the magnetic field’s generation in a thin convection shell with nonuniform helicity for large dynamo numbers is considered in the framework of Parker’s migratory dynamo. The obtained asymptotic solution of equations governing the magnetic field has a form of a modulated travelling dynamo wave. This wave propagates over the most latitudes of the solar hemisphere equatorwards, and the amplitude of the magnetic field first increases and then decreases with the propagation. Over the subpolar latitudes the dynamo wave reverses, there the dynamo wave propagates polewards and decays with latitude. Butterfly diagrams are plotted and analyzed.There is an attractive opportunity to develop a more quantitatively precise model taking into account helioseismological data on differential rotation and fitting the solar observational data on the magnetic field and turbulence, analyzing the helicity and the phase shift between toroidal and poloidal components of the field.

Download Full-text

Starspots Magnetic field by transit mapping

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314002129 ◽

2013 ◽

Vol 9 (S302) ◽

pp. 220-221

Author(s):

Adriana Válio ◽

Eduardo Spagiari

Keyword(s):

Magnetic Field ◽

Light Curve ◽

Field Component ◽

Solar Magnetic Field ◽

Line Of Sight ◽

The Sun ◽

Using Data ◽

The Magnetic Field ◽

Spot Temperature

AbstractSunspots are important signatures of the global solar magnetic field cycle. It is believed that other stars also present these same phenomena. However, today it is not possible to observe directly star spots due to their very small sizes. The method applied here studies star spots by detecting small variations in the stellar light curve during a planetary transit. When the planet passes in front of its host star, there is a chance of it occulting, at least partially, a spot. This allows the determination of the spots physical characteristics, such as size, temperature, and location on the stellar surface. In the case of the Sun, there exists a relation between the magnetic field and the spot temperature. We estimate the magnetic field component along the line-of-sight and the intensity of sunspots using data from the MDI instrument on board of the SOHO satellite. Assuming that the same relation applies to other stars, we estimate spots magnetic fields of CoRoT-2 and Kepler-17 stars.

Download Full-text

Solar Dynamical Processes I

Advanced Journal of Graduate Research ◽

10.21467/ajgr.3.1.47-61 ◽

2018 ◽

Vol 3 (1) ◽

pp. 47-61

Author(s):

Ashish Mishra ◽

Mukul Kumar

Keyword(s):

Magnetic Field ◽

Solar Magnetic Field ◽

Solar Interior ◽

Dynamo Model ◽

The Sun ◽

Dynamical Processes ◽

Flux Tubes ◽

Solar Prominences ◽

Magnetic Flux Tubes ◽

Theoretical Developments

The article gives a concise overview of solar dynamical processes and their impacts on the space weather. This article is based on the observational and theoretical developments made during last few decades. The article begins with a brief discussion of the Sun and the solar interior, from the core to the solar corona. We discuss the solar magnetic field and provide some basic understanding of the solar dynamo model. The solar dynamical processes, the transient as well as the gradual, are the manifestations of the Sun’s magnetic field. Magnetic reconnection, as well as submergence and emergence of magnetic flux tubes, plays an important role in the solar activities. This article tries to cover a range of dynamical processes, including sunspots, solar prominences and bright points. We also discussed various models of the dynamical processes along with their properties and effect on other activities occurring on the Sun.

Download Full-text

RSFP PREDICTIONS FOR TRANSVERSE SOLAR MAGNETIC FIELD DISTRIBUTION FROM SOLAR NEUTRINO DATA

Modern Physics Letters A ◽

10.1142/s0217732398001236 ◽

1998 ◽

Vol 13 (15) ◽

pp. 1163-1170 ◽

Cited By ~ 7

Author(s):

B. C. CHAUHAN ◽

U. C. PANDEY ◽

S. DEV

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Field Distribution ◽

Magnetic Moment ◽

Solar Neutrino ◽

Solar Magnetic Field ◽

Magnetic Field Distribution ◽

The Sun ◽

Solar Magnetic Fields ◽

The Magnetic Field

Even though the standard solar model (SSM) has been very successful in predicting the thermal and nuclear evolution of the Sun, it does not throw enough light on solar magnetic activity. In the absence of a generally accepted theory of solar dynamo, various general arguments have been put forth to constrain solar magnetic fields. In the absence of reliable knowledge of solar magnetic fields from available astrophysical data, it may be worthwhile to constrain the solar magnetic fields from solar neutrino observations assuming Resonant Spin-Flavor Precession (RSFP) to be responsible for the solar neutrino deficit. The configuration of solar magnetic field derived in this work is in reasonably good agreement with the magnetic field distribution proposed by Akhmedov et al. (Sov. Phys. JETP68, 250 (1989)). However, the magnetic field distribution in the radiation zone used by Pulido (Phys. Rep.211, 167 (1992)) is ruled out. The magnitude of the magnetic field in the radiation and convective zones of the Sun are very sensitive to the value chosen for the neutrino magnetic moment. However, any change in the value of neutrino magnetic moment does not affect the magnetic field distribution as it only scales the magnetic field strength at different points by the same amount.

Download Full-text

About long term modulation of cosmic rays in the 23-24 solar activity cycles

NMDB@Home 2020 - Cosmic ray studies with neutron detectors ◽

10.38072/2748-3150/p3 ◽

2021 ◽

pp. 23-29

Author(s):

Anatoly V. Belov ◽

Raisa T. Gushchina ◽

Victor Yanke

Keyword(s):

Magnetic Field ◽

Solar Activity ◽

Cosmic Rays ◽

Solar Magnetic Field ◽

The Sun ◽

Model Calculations ◽

Activity Cycles ◽

The Magnetic Field ◽

Solar Activity Cycles

Recently, there has been a significant trend in magnetic fields on the Sun. The total magnetic field of the Sun from the end of the 22nd cycle of solar activity (SA) has more than halved and this decrease continues. Chan- ges in the magnetic field are the key to all the active phenomena occurring on the Sun and in the heliosphere and, accordingly, to processes in cosmic rays. In long-term CR variations in 23-24 cycles of SA the attenuation of the solar magnetic field is displayed and these variations turned out to be the smallest for the entire time of CR observations. Model calculations of CR modulation for 21-22 and 23-24 cycles of SA showed: with a slight difference in the regression characteristics obtained, the distribution of contributions to the generated CR modulation from the effects of various SA indices is strongly varies in the analyzed periods. Possible reasons for the features of the last two CA cycles are discussed.

Download Full-text

MAGNETIC FIELD REVERSALS OF THE EARTH: A TWO–DISK RIKITAKE DYNAMO MODEL

International Journal of Modern Physics B ◽

10.1142/s0217979209063808 ◽

2009 ◽

Vol 23 (28n29) ◽

pp. 5492-5503 ◽

Cited By ~ 1

Author(s):

SANDRO DONATO ◽

DOMENICO MEDURI ◽

FABIO LEPRETI

Keyword(s):

Magnetic Field ◽

Laboratory Experiments ◽

Dynamo Model ◽

The Sun ◽

The Earth ◽

Simulation Based ◽

Dynamical Regimes ◽

Polarity Reversals ◽

Disk Dynamo ◽

The Magnetic Field

The Sun and the Earth possess dipolar magnetic fields that exhibit polarity reversals. Recent works, based on numerical simulations and laboratory experiments, found similar dynamical behaviours. We present results of a statistical analysis of a numerical simulation based on a generalized two–disk dynamo model. From a first investigation, we found that the dynamics of the system is controlled by the variations of the ratio of the torques and we observed different dynamical regimes characterized either by bursts or reversals, which can be periodic or random, of the magnetic field.

Download Full-text

Energetic particles and the solar cycle: Impact of solar magnetic field amplitude and geometry on SEPs and GCRs diffusion coefficients

10.5194/egusphere-egu21-6394 ◽

2021 ◽

Author(s):

Barbara Perri ◽

Allan Sacha Brun ◽

Antoine Strugarek ◽

Victor Réville

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Solar Cycle ◽

Diffusion Coefficients ◽

Solar Magnetic Field ◽

Energetic Particles ◽

Field Amplitude ◽

The Sun ◽

Magnetic Field Amplitude ◽

The Magnetic Field

<p>SEPs are correlated with the 11-year solar cycle due to their production by flares and interaction with the inner heliosphere, while GCRs are anti-correlated with it due to the modulation of the heliospheric magnetic field. The solar magnetic field along the cycle varies in amplitude but also in geometry, causing diffusion of the particles along and across the field lines; the solar wind distribution also evolves, and its turbulence affects particle trajectories.</p><p>We combine 3D MHD compressible numerical simulations to compute the configuration of the magnetic field and the associated polytropic solar wind up to 1 AU, with analytical prescriptions of the corresponding parallel and perpendicular diffusion coefficients for SEPs and GCRs. First, we analyze separately the impact of the magnetic field amplitude and geometry for a 100 MeV proton. By varying the amplitude, we change the amplitude of the diffusion by the same factor, and the radial gradients by changing the spread of the current sheet. By varying the geometry, we change the latitudinal gradients of diffusion by changing the position of the current sheets. We also vary the energy, and show that the statistical distribution of parallel diffusion is different for SEPs and GCRs. Then, we use realistic solar configurations, showing that diffusion is highly non-axisymmetric due to the configuration of the current sheets, and that the distribution varies a lot with the distance to the Sun, especially at minimum of activity. With this model, we are thus able to study the direct influence of the Sun on Earth spatial environment in terms of energetic particles.&#160;</p>

Download Full-text

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

International Astronomical Union Colloquium ◽

10.1017/s0252921100064630 ◽

2000 ◽

Vol 179 ◽

pp. 263-264

Author(s):

K. Sundara Raman ◽

K. B. Ramesh ◽

R. Selvendran ◽

P. S. M. Aleem ◽

K. M. Hiremath

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Magnetic Flux ◽

Ultra Violet ◽

Active Regions ◽

Morphological Properties ◽

Energy Storage And Conversion ◽

The Sun ◽

X Rays ◽

The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

Download Full-text

An 84-μG Magnetic Field in a Galaxy at Z=0.692?

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308027439 ◽

2008 ◽

Vol 4 (S254) ◽

pp. 95-96

Author(s):

Arthur M. Wolfe ◽

Regina A. Jorgenson ◽

Timothy Robishaw ◽

Carl Heiles ◽

Jason X. Prochaska

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Faraday Rotation ◽

Large Scale ◽

Dynamo Model ◽

Magnetic Field Generation ◽

Interstellar Gas ◽

Splitting Technique ◽

Average Value ◽

The Magnetic Field

AbstractThe magnetic field pervading our Galaxy is a crucial constituent of the interstellar medium: it mediates the dynamics of interstellar clouds, the energy density of cosmic rays, and the formation of stars (Beck 2005). The field associated with ionized interstellar gas has been determined through observations of pulsars in our Galaxy. Radio-frequency measurements of pulse dispersion and the rotation of the plane of linear polarization, i.e., Faraday rotation, yield an average value B ≈ 3 μG (Han et al. 2006). The possible detection of Faraday rotation of linearly polarized photons emitted by high-redshift quasars (Kronberg et al. 2008) suggests similar magnetic fields are present in foreground galaxies with redshifts z > 1. As Faraday rotation alone, however, determines neither the magnitude nor the redshift of the magnetic field, the strength of galactic magnetic fields at redshifts z > 0 remains uncertain.Here we report a measurement of a magnetic field of B ≈ 84 μG in a galaxy at z =0.692, using the same Zeeman-splitting technique that revealed an average value of B = 6 μG in the neutral interstellar gas of our Galaxy (Heiles et al. 2004). This is unexpected, as the leading theory of magnetic field generation, the mean-field dynamo model, predicts large-scale magnetic fields to be weaker in the past, rather than stronger (Parker 1970).The full text of this paper was published in Nature (Wolfe et al. 2008).

Download Full-text