scholarly journals Four Subjects in Solar Physics from the Point of View of the Electric Current Approach

2020 ◽  
pp. 33-45
Author(s):  
Syun-Ichi Akasofu
Keyword(s):  
Solar Wind ◽  
Electric Current ◽  
Solar Flares ◽  
Solar Physics ◽  
Current Approach ◽  
Point Of View ◽  
Coronal Temperature ◽  
The Past ◽  
Electromagnetic Processes ◽  
Difficult Subjects

Four major subjects in solar physics, the heating of the corona, the cause of the solar wind, the formation of sunspots and the cause of solar flares, are discussed on the basis of the electric current approach, a sequence of processes consisting of power supply(dynamo), transmission (currents/circuits) and dissipation(high coronal temperature, solar wind, sunspots and solar flares).This is because the four subjects have hardly been considered in terms of the electric current approach in the past, in spite of the fact that these subjects are various manifestations of electromagnetic processes. It is shown that this approach provides a new systematic way of considering each subject; (1) the long-standing issue of the coronal temperature, (2)the long-standing problem on the cause of the solar wind, (3)the presence of single spots(forgotten or dismissed in the past) and its relation to unipolar magnetic regions and (4) the crucial power/energy source and subsequent explosive processes of solar flares. The four subjects are obviously extremely complicated and difficult subjects, but it is hoped that the electric current approach might provide a new insight in considering the four subjects.

Magnetic Reconnection in the Earth's Magnetotail

1985 ◽  
Vol 38 (6) ◽  
pp. 981 ◽  
Author(s):  
Edward W Hones Jr
Keyword(s):  
Solar Wind ◽  
Magnetic Reconnection ◽  
Plasma Sheet ◽  
Solar Flares ◽  
Reasonable Doubt ◽  
Physical Processes ◽  
Geomagnetic Disturbances ◽  
Magnetospheric Substorms ◽  
The Past ◽  
Fundamental Physical

Over the past few years satellite observations of the plasma sheet in the Earth's magnetotail during magnetospheric substorms have established beyond reasonable doubt that magnetic reconnection occurs in the magnetotail and that it plays a central role in the substorm process. The features seen at Earth by which substorms were originally identified (e.g. the auroras and geomagnetic disturbances) are simply superficial manifestations of a more fundamental physical process-the magnetosphere divesting itself of stored energy and plasma that was acquired earlier from the solar wind. It does so by shedding a part of its plasma sheet. This is accomplished by magnetic reconnection near the Earth that severs the plasma sheet, forming a plasmoid that flows out of the tail and that is lost to the solar wind. Recognition of the existence of plasmoids and our developing understanding of them have been important elements in confirming the occurrence of reconnection in the magnetosphere. In an analogous way, the best evidence for the occurrence of reconnection on the Sun has come from observations of closed magnetic configurations (plasmoids) in the solar wind and in the corona. But while magnetic reconnection is certainly the key ingredient in solar flares and substorms, analogies between them should not be carried too far, because there are basic differences in the environments in which they prevail and in the physical procesSes that lead to their occurrence.

The record of solar and galactic radiations in the ancient lunar regolith and their implications for the early history of the Sun and Moon

1977 ◽  
Vol 285 (1327) ◽  
pp. 587-592 ◽  
Keyword(s):  
Solar Wind ◽  
Solar Flare ◽  
Solar Flares ◽  
Lunar Regolith ◽  
Galactic Cosmic Rays ◽  
Flare Activity ◽  
New Techniques ◽  
The Past ◽  
History Of ◽  
Individual Grains

A variety of techniques are available for studying past variations of solar wind, solar flares, galactic cosmic rays, and micrometeorites. Lumar rock results which average over the recent past ( ~ 10 Ma) indicate no major changes in any of these components. At longer times, recent data suggest secular changes in the 15N/14N ratio in the solar wind, possibly due to enhanced solar flare activity. With the deployment of new techniques, it now appears possible to measure solar wind, solar flare, and micrometeorite records in individual grains removed from different layers of lunar cores. Such grains have been exposed for brief intervals of time (103-104 a) for times extending at least 109 a in the past. Lunar and meteoritic breccias are promising candidates for extending the record back still further, perhaps close to the beginning of the solar system.

scholarly journals Quasi-Two-Dimensional Cosmic Jets

1985 ◽  
Vol 107 ◽  
pp. 497-501
Author(s):  
K. Tsinganos ◽  
A. Ferrari ◽  
R. Rosner
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
Solar Physics ◽  
Coronal Holes ◽  
Star Forming ◽  
Ss 433 ◽  
The Past ◽  
Astrophysical Jet ◽  
Speed Solar Wind ◽  
High Speed Solar Wind

One of the major discoveries in solar physics over the past decade has been the association of coronal holes with high-speed solar wind streams (Zirker 1977 and references therein). On the other hand, advances in X-ray and radio instrumentation (e.g., Einstein, VLA, VLBI, etc.) in the past few years have allowed detailed observations of collimated outflows from rather more distant objects, such as young stars and active galaxies (Beer 1981, Lada 1982, Ferrari and Pacholczyk 1983 and references therein). The remarkable structural similarities between jets of magnetized gas from our Sun, other active stars, and active galactic nuclei suggest that these phenomena may be manifestations of similar hydrodynamic processes operating on both small and large scales. In this article, we shall use the experience gained by studying the nearest known astrophysical jet - high-speed solar wind streams - to address some of the problems of astrophysical jet acceleration and collimation associated with objects as diverse as SS 433, star-forming molecular clouds and, in particular, jets associated with galaxies and quasars.

scholarly journals VIII. Theory of Flares

1985 ◽  
Vol 19 (1) ◽  
pp. 90-96
Author(s):  
E. R. Priest
Keyword(s):  
Active Region ◽  
Solar Flares ◽  
Solar Maximum ◽  
Solar Physics ◽  
Type A ◽  
Loop Structure ◽  
Simple Loop ◽  
Solar Maximum Mission ◽  
The Past ◽  
Chromospheric Emission

Magnetohydrodynamic (MHD) theory for the initiation and development of solar flares has developed considerably over the past 3 years and represents one of the liveliest areas of solar physics (Hood & Priest, 1981a, Priest 1983a, b, Schindler 1982, Van Hoven 1982, Syrovatskii et al. 1983). This has been stimulated by a thorough analysis of the Skylab observations and also by the startling new observations from the Solar Maximum Mission (SMM). In addition, the realization that flares appear to form two basic types, namely, small simple-loop flares and large two-ribbon flares, has focussed the imagination of theorists (e.g.. Priest 1981, 1982), even though reality may be somewhat more complex. In the former type, a single-loop structure brightens up and decays without moving; whereas in the latter, an active region filament erupts and then two ribbons of chromospheric emission form and separate, with an arcade of hot and cool loops joining them.

scholarly journals A Review of Studies of Geomagnetic Storms and Auroral/Magnetospheric Substorms Based on the Electric Current Approach

2021 ◽  
Vol 7 ◽  
Author(s):  
Syun-Ichi Akasofu
Keyword(s):  
Electric Current ◽  
Geomagnetic Storms ◽  
Current Approach ◽  
Space Physics ◽  
Point Of View ◽  
Magnetospheric Substorms ◽  
New Science ◽  
Auroral Substorms ◽  
The Magnetic Field ◽  
Present Understanding

The progress of space physics is reviewed from my personal point of view, particularly how I have reached my present understanding of auroral substorms and geomagnetic storms from the time of the earliest days of space physics. This review is somewhat unique in two ways. First of all, instead of taking the magnetic field line approach (including magnetic reconnection), I have taken the electric current approach; it consists of power supply (dynamo), transmission (currents/circuits), and dissipation (auroral/magnetospheric substorms). This is the basic way to study electromagnetic phenomena and it is much more instructive in understanding the physics involved in the chain processes. Secondly, this is not a textbook-like review, but it is hoped that my humble experience may be useful to see how a new science of space physics has evolved with a number of controversies. On the other hand, it can be seen that the electric current approach is still in a very rudiment stage. Thus, new generations of researchers are most welcome in taking this new way of studying auroral/magnetospheric substorms and geomagnetic storms.

scholarly journals The electric current approach in the solar–terrestrial relationship

2017 ◽  
Vol 35 (4) ◽  
pp. 965-978 ◽  
Author(s):  
Syun-Ichi Akasofu
Keyword(s):  
Electric Current ◽  
Solar Flares ◽  
Power Transmission ◽  
Geomagnetic Storms ◽  
Magnetic Energy ◽  
Current Approach ◽  
Electric Currents ◽  
Auroral Substorms ◽  
The Magnetic Field ◽  
Insight Into

Abstract. The sequence of phenomena consisting of solar flares, coronal mass ejections (CMEs), auroral substorms, and geomagnetic storms is mostly a manifestation of electromagnetic energy dissipation. Thus, first of all, it is natural to consider each of them in terms of a sequence of power supply (dynamo), power transmission (electric currents/circuits), and dissipation (mostly observed phenomena), i.e., as an input–output process and the electric current line approach. Secondly, extending this concept, it is attempted in this paper to consider the whole solar–terrestrial relationship in terms of electric currents. This approach enables us to follow through not only the sequence in solar flares, auroral substorms, and geomagnetic storms but also to connect all phenomena naturally as a continuous flow of magnetic energy (V[B2∕8π]) from the sun across the magnetopause. This consideration gives some insight into all the processes involved equally well compared with the magnetic field line approach, which has been adopted almost exclusively in the past.

scholarly journals Measurements of the direction of the solar wind using interplanetary scintillation

1998 ◽  
Vol 16 (10) ◽  
pp. 1259-1264 ◽  
Author(s):  
P. J. Moran ◽  
A. R. Breen ◽  
C. A. Varley ◽  
P. J. S. Williams ◽  
W. P. Wilkinson ◽  
...  
Keyword(s):  
Solar Wind ◽  
Plasma Flow ◽  
Solar Physics ◽  
Extended Period ◽  
Radial Component ◽  
Unique Determination ◽  
Interplanetary Scintillation ◽  
Maximum Correlation ◽  
The Past

Abstract. EISCAT observations of the interplanetary scintillation of a single source were made over an extended period of time, during which the orientation of the baselines between the two observing sites changed significantly. Assuming that maximum correlation between the scintillations observed at the two sites occurs when the projected baseline is parallel to the direction of plasma flow, this technique can be used to make a unique determination of the direction of the solar wind. In the past it has usually been assumed that the plasma flow is radial, but measurements of eleven sources using this technique have indicated conclusively that in at least six cases observed at mid or high heliocentric latitude there is a significant non-radial component directed in four cases towards the heliocentric equator and in two cases towards the pole.Key words. Solar physics · Astrophysics · Astronomy · Magnetic fields · Space plasma physics · Charged particle motion and acceleration

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