scholarly journals Large-Scale Solar Magnetic Fields

1976 ◽  
Vol 71 ◽  
pp. 47-67 ◽  
Author(s):  
V. Bumba
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Distribution ◽  
Large Scale ◽  
Solar Magnetic Field ◽  
Magnetic Measurements ◽  
Preliminary Investigation ◽  
Longitudinal Distribution ◽  
Solar Magnetic Fields ◽  
Background Fields

The characteristics of the large-scale distribution of the solar magnetic fields on the basis of a series of solar magnetic synoptic charts covering more than 15 years of observations are given. The major part of our information concerns the morphology and only some results deal with the kinematics of the field distribution. Results of averaged solar magnetic field fluxes and polarity reversal studies as well as of preliminary investigation of the very-low angular resolution magnetic measurements are given. The regular zonal and sectoral distribution of photospheric background fields, the different role or visibility of structures in both polarities is discussed. The reflection of both main types of the longitudinal distribution of large-scale solar background magnetic fields (the 27-day, the 28–29-day successions, the ‘supergiant’ structures) in the interplanetary magnetic field distribution is also considered.

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

1998 ◽  
Vol 13 (15) ◽  
pp. 1163-1170 ◽  
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.

scholarly journals Progress in the Measurement of Solar Magnetic Fields

1993 ◽  
Vol 141 ◽  
pp. 149-155 ◽  
Author(s):  
Guoxiang Ai
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
White Light ◽  
Historical Development ◽  
Solar Magnetic Field ◽  
Solar Physics ◽  
Monochromatic Light ◽  
Velocity Fields ◽  
Solar Magnetic Fields ◽  
Optical Instruments

AbstractThe historical development of optical instruments for solar physics is outlined, from white light to unpolarized and polarized monochromatic light, to Stokes profiles and simultaneous fields of view, from points to lines, plane to cube. An evolutionary series and classificaton of instruments for the solar magnetic field is described. As a next step the 2-D real time polarizing spectrograph has been proposed. The planned instruments in China for measurements of solar magnetic and velocity fields are briefly introduced.

scholarly journals Reconstructing solar magnetic fields from historical observations

2019 ◽  
Vol 627 ◽  
pp. A11
Author(s):  
I. O. I. Virtanen ◽  
I. I. Virtanen ◽  
A. A. Pevtsov ◽  
L. Bertello ◽  
A. Yeates ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Active Regions ◽  
Long Term Evolution ◽  
Photospheric Magnetic Field ◽  
Solar Magnetic Fields ◽  
Term Evolution ◽  
Large Scale Field

Aims. The evolution of the photospheric magnetic field has only been regularly observed since the 1970s. The absence of earlier observations severely limits our ability to understand the long-term evolution of solar magnetic fields, especially the polar fields that are important drivers of space weather. Here, we test the possibility to reconstruct the large-scale solar magnetic fields from Ca II K line observations and sunspot magnetic field observations, and to create synoptic maps of the photospheric magnetic field for times before modern-time magnetographic observations. Methods. We reconstructed active regions from Ca II K line synoptic maps and assigned them magnetic polarities using sunspot magnetic field observations. We used the reconstructed active regions as input in a surface flux transport simulation to produce synoptic maps of the photospheric magnetic field. We compared the simulated field with the observed field in 1975−1985 in order to test and validate our method. Results. The reconstruction very accurately reproduces the long-term evolution of the large-scale field, including the poleward flux surges and the strength of polar fields. The reconstruction has slightly less emerging flux because a few weak active regions are missing, but it includes the large active regions that are the most important for the large-scale evolution of the field. Although our reconstruction method is very robust, individual reconstructed active regions may be slightly inaccurate in terms of area, total flux, or polarity, which leads to some uncertainty in the simulation. However, due to the randomness of these inaccuracies and the lack of long-term memory in the simulation, these problems do not significantly affect the long-term evolution of the large-scale field.

scholarly journals Analog Video Magnetograms in Real Time

1971 ◽  
Vol 43 ◽  
pp. 76-83 ◽  
Author(s):  
R. C. Smithson ◽  
R. B. Leighton
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Magnetic Field ◽  
Solar Spectrum ◽  
Zeeman Splitting ◽  
The Other ◽  
Line Of Sight ◽  
Zero Field ◽  
The Sun ◽  
Solar Magnetic Fields

For many years solar magnetic fields have been measured by a variety of techniques, all of which exploit the Zeeman splitting of lines in the solar spectrum. One of these techniques (Leighton, 1959) involves a photographic subtraction of two monochromatic images to produce a picture of the Sun in which the line-of-sight component of the solar magnetic field appears as various shades of gray. In a magnetogram made by this method, zero field strength appears as neutral gray, while magnetic fields of one polarity or the other appear as lighter or darker areas, respectively. Figure 1 shows such a magnetogram.

scholarly journals Transient Events and Their Solar Magnetic Field

1998 ◽  
Vol 11 (2) ◽  
pp. 877-879
Author(s):  
J.-C. Vial
Keyword(s):  
Magnetic Field ◽  
Particle Acceleration ◽  
Magnetic Fields ◽  
Coronal Mass Ejections ◽  
Solar Magnetic Field ◽  
Solar Magnetic Fields ◽  
Radio Network ◽  
Excellent Review ◽  
X Ray ◽  
Transient Events

Excellent review papers have been presented in this session by S. Solanki (Manifestations of solar magnetic fields), K. Dere (Coronal Mass Ejections and interplanetary ejecta) and W. Droege (Particle acceleration by waves and fields) and the relevant texts can be found in this volume.The Joint Discussion benefited from three contributed papers: X-Ray/Radio network flares of the quiet Sun by A.O. Benz, S. Krucker, L.W. Acton, and T.S. Bastian (presented by A.O. Benz) Radio observations of coronal X-ray jets by M.R. Kundu

scholarly journals Manifestations of Solar Magnetic Fields

1998 ◽  
Vol 11 (2) ◽  
pp. 857-860
Author(s):  
S.K. Solanki
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Magnetic Field ◽  
Magnetic Activity ◽  
The Sun ◽  
Solar Magnetic Fields ◽  
Quiet Sun ◽  
Solar Magnetic Activity

AbstractThe magnetism of the Sun manifests itself in innumerable ways, many of which constitute what is referred to as solar magnetic activity, while others are counted among the phenomena of the quiet Sun. After a brief overview of the structure of the solar magnetic field, a few examples of its manifestations are pointed out.

scholarly journals Dynamics of Large-Scale Magnetic Fields

1971 ◽  
Vol 43 ◽  
pp. 737-743 ◽  
Author(s):  
G. V. Kuklin
Keyword(s):  
Magnetic Field ◽  
Velocity Field ◽  
Magnetic Fields ◽  
Joint Action ◽  
Large Scale ◽  
Solar Magnetic Fields

A discussion is given of the dynamics of large-scale solar magnetic fields as a joint action of a transport by a regular velocity field, by a generalized diffusion, by coming to the surface and sinking and by sources of origin and destruction of magnetic fields. Also these processes are discussed using the observed picture of magnetic field dynamics.

scholarly journals Large Scale Solar Magnetic Fields and Their Consequences

1971 ◽  
Vol 43 ◽  
pp. 547-568 ◽  
Author(s):  
Gordon Newkirk
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Magnetic Fields ◽  
Differential Rotation ◽  
Large Scale ◽  
Mechanical Energy ◽  
Rotation Period ◽  
Small Scale ◽  
Solar Magnetic Fields ◽  
Radio Bursts

The general properties of large scale solar magnetic fields are reviewed. In order of size these are: (1) Active region, generally bipolar fields with a lifetime of about two solar rotations. These are characterized by fields of several hundred G and display differential rotation similar to that found for the photosphere. (2) UM regions which appear to be the remnants of active region fields dispersed by the action of supergranulation convection and distorted by differential rotation. These are characterized by fields of a few tens of gauss and have lifetimes of several solar rotations. (3) The polar fields which are built up over the solar cycle by the preferential migration of a given polarity towards the poles. The poloidal fields are of a few gauss in magnitude and reverse sign in about 22 yr. (4) The large scale sector fields. These appear closely related to the interplanetary sector structure, cover tens of degrees in longitude, and stretch across the equator with the same polarity. This pattern endures for periods of up to a year or more, is not distorted by differential rotation, and has a rotation period of about 27 days. The presence of these long enduring sector fields may be related to the phenomenon of active solar longitudes. The consequences of large scale fields are examined with particular emphasis on the effects displayed by the corona. Calculated magnetic field patterns in the corona are compared with the density structure of the corona with the conclusion that: (1) Small scale structures in the corona, such as rays, arches, and loops, reflect the shape of the field and appear as magnetic tubes of force preferentially filled with more coronal plasma than the background. (2) Coronal density enhancements appear over plages where the field strength and presumably the mechanical energy transport into the corona are higher than normal. (3) Coronal streamers form above the ‘neutral line’ between extended UM regions of opposite polarity. The role played by coronal magnetic fields in transient events is also discussed. Some examples are: (1) The location of Proton Flares in open, diverging configurations of the field. (2) The expulsion of ‘magnetic bottles’ into the interplanetary medium by solar flares. (3) The relation of Type IV radio bursts to the ambient field configuration. (4) The guiding of Type II burst exciters by the ambient magnetic field. (5) The magnetic connection between widely separated active regions which display correlated radio bursts.

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