Particle Acceleration in the Process of Eruptive Opening and Reconnection of Magnetic Fields

In a series of papers on the flare of 29 July 1973 (Nolte et al., 1979; Martin, 1979; Švestka et al., 1979) it has been shown that Hα “post-flare” loops are the cooled aftermath of previously hot coronal loops which were visible in x-rays in the same position earlier in the flare. Kopp and Pneuman (1976) have proposed that these post-flare loops are formed by a process of successive magnetic field reconnections of previously distended magnetic field lines as illustrated in Figure 1. Each successive reconnection of the magnetic field yields a closed magnetic loop that forms above and concentric with previously formed loops. A shock wave created during each sudden reconnection travels down both legs of each loop and provides energy for ionizing chromospheric mass at the footpoints of the loop. Subsequent condensation of the ionized mass at the tops of the loops renders them visible as this mass falls to the chromosphere.

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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.

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Magnetic Field Spectroheliograms from the San Fernando Observatory

Symposium - International Astronomical Union ◽

10.1017/s0074180900022774 ◽

1971 ◽

Vol 43 ◽

pp. 329-339 ◽

Cited By ~ 30

Author(s):

Dale Vrabec

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Spiral Structure ◽

Longitudinal Component ◽

Solar Telescope ◽

Solar Magnetic Fields ◽

San Fernando ◽

Field Lines ◽

The Magnetic Field ◽

Field Network

Zeeman spectroheliograms of photospheric magnetic fields (longitudinal component) in the CaI 6102.7 Å line are being obtained with the new 61-cm vacuum solar telescope and spectroheliograph, using the Leighton technique. The structure of the magnetic field network appears identical to the bright photospheric network visible in the cores of many Fraunhofer lines and in CN spectroheliograms, with the exception that polarities are distinguished. This supports the evolving concept that solar magnetic fields outside of sunspots exist in small concentrations of essentially vertically oriented field, roughly clumped to form a network imbedded in the otherwise field-free photosphere. A timelapse spectroheliogram movie sequence spanning 6 hr revealed changes in the magnetic fields, including a systematic outward streaming of small magnetic knots of both polarities within annular areas surrounding several sunspots. The photospheric magnetic fields and a series of filtergrams taken at various wavelengths in the Hα profile starting in the far wing are intercompared in an effort to demonstrate that the dark strands of arch filament systems (AFS) and fibrils map magnetic field lines in the chromosphere. An example of an active region in which the magnetic fields assume a distinct spiral structure is presented.

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Probing interstellar magnetic fields with Supernova remnants

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309030087 ◽

2008 ◽

Vol 4 (S259) ◽

pp. 75-80 ◽

Cited By ~ 2

Author(s):

Roland Kothes ◽

Jo-Anne Brown

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Supernova Remnants ◽

Large Scale ◽

Galactic Plane ◽

Field Configuration ◽

Large Scale Magnetic Field ◽

Rotation Measure ◽

Field Lines ◽

The Magnetic Field

AbstractAs Supernova remnants expand, their shock waves are freezing in and compressing the magnetic field lines they encounter; consequently we can use Supernova remnants as magnifying glasses for their ambient magnetic fields. We will describe a simple model to determine emission, polarization, and rotation measure characteristics of adiabatically expanding Supernova remnants and how we can exploit this model to gain information about the large scale magnetic field in our Galaxy. We will give two examples: The SNR DA530, which is located high above the Galactic plane, reveals information about the magnetic field in the halo of our Galaxy. The SNR G182.4+4.3 is located close to the anti-centre of our Galaxy and reveals the most probable direction where the large-scale magnetic field is perpendicular to the line of sight. This may help to decide on the large-scale magnetic field configuration of our Galaxy. But more observations of SNRs are needed.

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Structure of magnetic fields in spiral galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309031287 ◽

2008 ◽

Vol 4 (S259) ◽

pp. 551-552

Author(s):

Hanna Kotarba ◽

H. Lesch ◽

K. Dolag ◽

T. Naab ◽

P. H. Johansson ◽

...

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Homogeneous Field ◽

Field Equations ◽

The Galaxy ◽

Induction Equation ◽

Tight Connection ◽

Field Lines ◽

The Magnetic Field ◽

Direct Implementation

AbstractWe present a set of global, self-consistentN-body/SPH simulations of the dynamic evolution of galactic discs with gas and including magnetic fields. We have implemented a description to follow the ideal induction equation in the SPH part of the codeVine. Results from a direct implementation of the field equations are compared to a representation by Euler potentials, which pose a ∇ ċB-free description, a constraint not fulfilled for the direct implementation. All simulations are compared to an implementation of magnetic fields in the codeGadget. Starting with a homogeneous field we find a tight connection of the magnetic field structure to the density pattern of the galaxy in our simulations, with the magnetic field lines being aligned with the developing spiral pattern of the gas. Our simulations clearly show the importance of non-axisymmetry of the dynamic pattern for the evolution of the magnetic field.

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On Special Features of Non-Thermal Solar X Radiation above 10 keV

International Astronomical Union Colloquium ◽

10.1017/s0252921100089958 ◽

1972 ◽

Vol 14 ◽

pp. 761-762

Author(s):

G. Elwert ◽

E. Haug

Keyword(s):

Magnetic Field ◽

Angular Distribution ◽

Power Law ◽

Impulsive Phase ◽

X Rays ◽

Energetic Electrons ◽

X Ray ◽

Preferred Direction ◽

Field Lines ◽

The Magnetic Field

The polarization and angular distribution of solar hard X radiation above 10 keV was calculated under the assumption that the X rays originate as bremsstrahlung from energetic electrons moving in a preferred direction. The source electrons are supposed to have a power-law spectrum. These conditions are to be expected in the impulsive phase of an X-ray burst. The spiral orbits of the electrons around the magnetic field lines are taken into account.

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Measuring Magnetic Fields from Water Masers Associated with a Synchrotron Protostellar Jet

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318000017 ◽

2017 ◽

Vol 13 (S336) ◽

pp. 215-218

Author(s):

Ciriaco Goddi ◽

Gabriele Surcis

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Zeeman Splitting ◽

High Mass ◽

Local Magnetic Field ◽

Mass Star ◽

Dominant Component ◽

Field Lines ◽

Water Masers ◽

The Magnetic Field

AbstractThe Turner-Welch Object in the W3(OH) high-mass star forming complex drives a synchrotron jet, which is quite exceptional for a high-mass protostar, and is associated with a strongly polarized water maser source, W3(H2O), making it an optimal target to investigate the role of magnetic fields on the innermost scales of protostellar disk-jet systems. We report here full polarimetric VLBA observations of water masers. The linearly polarized emission from water masers provides clues on the orientation of the local magnetic field, while the measurement of the Zeeman splitting from circular polarization provides its strength. By combining the information on the measured orientation and strength of the magnetic field with the knowledge of the maser velocities, we infer that the magnetic field evolves from having a dominant component parallel to the outflow velocity in the pre-shock gas (with field strengths of the order of a few tens of mG), to being mainly dominated by the perpendicular component (of order of a few hundred of mG) in the post-shock gas where the water masers are excited. The general implication is that in the undisturbed (i.e. not-shocked) circumstellar gas, the flow velocities would follow closely the magnetic field lines, while in the shocked gas the magnetic field would be re-configured to be parallel to the shock front as a consequence of gas compression.

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V. Heating and Dynamics of Chromosphere and Corona

Transactions of the International Astronomical Union ◽

10.1017/s0251107x00007021 ◽

1988 ◽

Vol 20 (1) ◽

pp. 100-102

Author(s):

G.E. Brueckner

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Acoustic Waves ◽

Convection Zone ◽

Flux Tubes ◽

Magnetic Structures ◽

Convective Motions ◽

Field Lines ◽

The Magnetic Field

The crucial role of magnetic fields in any mechanism to heat the outer solar atmosphere has been generally accepted by all authors. However, there is still no agreement about the detailed function of the magnetic field. Heating mechanisms can be divided up into 4 classes: (I) The magnetic field plays a passive role as a suitable medium for the propagation of Alfvén waves from the convection zone into the corona (Ionson, 1984). (II) In closed magnetic structures the slow random shuffling of field lines by convective motions below the surface induces electric currents in the corona which heat it by Joule dissipation (Heyvaerts and Priest, 1984). (Ill) Emerging flux which is generated in the convection zone reacts with ionized material while magnetic field lines move through the chromosphere, transition zone and corona. Rapid field line annihilation, reconnection and drift currents result in heating and material ejection (Brueckner, 1987; Brueckner et al., 1987; Cook et al., 1987). (IV) Acoustic waves which could heat the corona can be guided by magnetic fields. Temperature distribution, wave motions and shock formation are highly dependent on the geometry of the flux tubes (Ulmschneider and Muchmore, 1986; Ulmschneider, Muchmore and Kalkofen, 1987).

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Convective mechanism of amplification and structuring of magnetic fields

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313002366 ◽

2012 ◽

Vol 8 (S294) ◽

pp. 137-142

Author(s):

A. V. Getling ◽

V. V. Kolmychkov ◽

O. S. Mazhorova

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Incompressible Fluid ◽

Spatial Scales ◽

Fluid Motion ◽

Horizontal Layer ◽

Field Lines ◽

The Magnetic Field ◽

Initial Magnetic Field ◽

Peripheral Regions

AbstractMagnetoconvection in a horizontal layer of incompressible fluid is simulated numerically. The initial magnetic field is assumed to be uniform and horizontal. The interaction of quasi-ordered cellular convection with the magnetic field is shown to be able to produce bipolar (and also diverse more complex) configurations of a substantially amplified magnetic field. The operation of this mechanism, which can be regarded as a modification of the mechanism suggested by Tverskoi (1966), is controlled by the very topology of the cellular flow, should be manifest on various spatial scales, and does not require strong initial fields. Magnetic configurations develop both in the central parts of convection cells, where circulatory fluid motion “winds” magnetic field lines, and in the network formed by their peripheral regions due to the “sweeping” of magnetic field lines.

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Magnetic fields in limb solar flares on heights 2–14 Mm

Bulletin of Taras Shevchenko National University of Kyiv Astronomy ◽

10.17721/btsnua.2020.61.06-14 ◽

2020 ◽

pp. 6-14

Author(s):

V. Lozitsky ◽

I. Yakovkin ◽

E. Kravchenko

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Solar Flares ◽

Zeeman Splitting ◽

Local Magnetic Field ◽

Echelle Spectrograph ◽

Superstrong Magnetic Field ◽

National University ◽

Field Lines ◽

The Magnetic Field

We present the results of observations of two powerful limb solar flares which occured on 17 July 1981 and 14 July 2005. Spectral observations of these flares were carried out with the Echelle spectrograph of the Horizontal Solar Telescope of the Astronomical Observatory of Taras Shevchenko National University of Kyiv. In order to measure the magnetic fields in these flares, I ± V profiles of К СаІІ, HeI 4471.5 and Нα lines were studied. It was found that effective (averaged) magnetic field Вeff in the flares reached 1100–3000 G on heights 2–14 Mm. However, the spectral evidences to yet stronger fields of ~ 104 G range were found. In particular, the weak spectral evidences of large Zeeman splitting were found in first flare by HeI 4471.5 line; this evidences corresponds to superstrong magnetic field of 15.5 kG. In the second flare, Нα line has non-parallelism of bisectors of I ± V profiles which can reflect existence of 1550–3000 G fields in the flare. However, in frame of simple two-component model these observed values can correspond to true local (amplitude) magnetic fields Вmax in range 4.65–18 kG. Apparently, such superstrong magnetic fields arise in structures of a force-free type, with strong twisting of the field lines. It is precisely such field values that are necessary in solar flares for energy reasons. Indeed, solar flares emit energy in the range of 1027-1032 erg in a volume of the order of 1027 cm3. Elementary calculations show that in order to provide such energy in such a volume, the magnetic field strength should be at least 103 G. In addition, if we take into account that solar magnetic fields have the sub-telescopic (spatially unresolved) structure, then the local magnetic field intensities in the flares at the coronal level can be expected even higher.

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Study of the effect of electromagnetic field and radiation on the intensification of brewi ng processes

Technology audit and production reserves ◽

10.15587/2706-5448.2021.230367 ◽

2021 ◽

Vol 2 (3(58)) ◽

pp. 44-46

Author(s):

Vasilij Sidor ◽

Svitlana Usatiuk ◽

Olena Tyshchenko ◽

Iryna Baranovska

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Electromagnetic Waves ◽

X Rays ◽

Barley Malt ◽

Enzyme Preparations ◽

The Individual ◽

Increased Activity ◽

Positive Effect ◽

The Magnetic Field

The object of research is the enzymatic preparations Termamil and San-Super, malt and yeast. One of the most problematic places is that the action of the magnetic field and radiation can both stimulate the amylase activity of barley malt and cause its deactivation. During the study, a certain number of electrophysical factors were used, namely: laser radiation, which was carried out using a helium-neon laser, ultraviolet radiation – using a nitrogen gas laser, X-rays, a constant uniform magnetic field, ultrasound. Results have been obtained that confirm the positive effect of the magnetic field on the activation of the amyloletic activity of concentrated preparations. A study was also conducted in accordance with the effect of electromagnetic waves on the activation of enzymes in barley and wheat malt, which showed a positive effect. This is ensured by the fact that in the course of the study, thanks to experiments, the best duration of irradiation with electromagnetic waves and different types of radiation for enzyme preparations, malt and yeast was found. These methods have a number of features. This is the availability of the appropriate equipment and knowledge of the individual types of rays, magnetic fields and electromagnetic waves, and their potential effects on enzymes, as well as control of the exposure time and magnetic field load. Due to the action of electromagnetic waves and radiation, for a certain amount of time, it is possible to obtain an increased activity of enzymatic preparations. Compared to the fermentative preparations Termamil and San-Super, malt and yeast, which are not susceptible to the load of magnetic fields, electromagnetic waves and various types of radiation, the fermentative preparations Termamil and San-Super, malt and yeast, which were susceptible to the action of electromagnetic waves, as well as radiation show increased activity of action. At the same time, these preparations reduce the amount of costs and increase the yield of finished products, which will serve as a positive aspect for the economic sphere of the enterprise.

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