scholarly journals Sector Structure of the Solar Magnetic Field

1971 ◽  
Vol 43 ◽  
pp. 744-753 ◽  
Author(s):  
John M. Wilcox
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Solar Magnetic Field ◽  
Photospheric Magnetic Field ◽  
The Other ◽  
The Sun ◽  
Sector Structure ◽  
Sector Boundary ◽  
The North

The solar sector structure consists of a boundary in the north-south direction such that on one side of the boundary the large-scale weak photospheric magnetic field is predominantly directed out of the Sun, and on the other side of the boundary this field is directed into the Sun. The region westward of a solar sector boundary tends to be unusually quiet and the region eastward of a solar sector boundary tends to be unusually active. This tendency is discussed in terms of flares, coronal enhancements, plage structure and geomagnetic response.

scholarly journals Long Term Evolution of Solar Sector Structure

1976 ◽  
Vol 71 ◽  
pp. 135-135
Author(s):  
Leif Svalgaard ◽  
John M. Wilcox
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Large Scale ◽  
Solar Magnetic Field ◽  
Rotation Period ◽  
Sunspot Cycle ◽  
The Sun ◽  
Sector Structure ◽  
Sunspot Maximum ◽  
The Past

The large-scale structure of the solar magnetic field during the past five sunspot cycles (representing by implication a much longer interval of time) has been investigated using the polarity (toward or away from the Sun) of the interplanetary magnetic field as inferred from polar geomagnetic observations. The polarity of the interplanetary magnetic field has previously been shown to be closely related to the polarity (into or out of the Sun) of the large-scale solar magnetic field. It appears that a solar structure with four sectors per rotation persisted through the past five sunspot cycles, with a synodic rotation period near 27.0 days, and a small relative westward drift during the first half of each sunspot cycle and a relative eastward drift during the second half of each cycle. Superposed on this four-sector structure there is another structure with inward field polarity, a width in solar longitude of about 100° and a synodic rotation period of about 28 to 29 days. This 28.5 day structure is usually most prominent during a few years near sunspot maximum. Some preliminary comparisons of these observed solar structures with theoretical considerations are given.

scholarly journals Time Evolution of the Large-Scale Solar Magnetic Field

1971 ◽  
Vol 43 ◽  
pp. 588-594 ◽  
Author(s):  
Martin D. Altschuler ◽  
Gordon Newkirk ◽  
Dorothy E. Trotter ◽  
Robert Howard
Keyword(s):  
Magnetic Field ◽  
Time Evolution ◽  
Large Scale ◽  
Solar Magnetic Field ◽  
Magnetic Polarity ◽  
Zonal Harmonic ◽  
The North

The six years of data from the Mt. Wilson Magnetic Atlas were analyzed in terms of surface harmonics. Between 1959 and 1962 the dominant harmonic corresponded to a dipole lying in the plane of the equator (2 sectors). There was also a significant zonal harmonic in which both solar poles had the same magnetic polarity, opposite to that at the equator. From the end of 1962 through 1964, the harmonic corresponding to 4 sectors was dominant. In 1965 and 1966, the harmonic of the north-south dipole became significant.

scholarly journals Reconstruction of Sun-as-Star Magnetic Field Structure and Evolution Using Filament Observations

1998 ◽  
Vol 167 ◽  
pp. 493-496
Author(s):  
Dmitri I. Ponyavin
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Large Scale ◽  
Solar Magnetic Field ◽  
Close Association ◽  
Field Structure ◽  
The Sun ◽  
Magnetic Field Structure ◽  
Large Scale Magnetic Field ◽  
Field Organization

AbstractA technique is used to restore the magnetic field of the Sun viewed as star from the filament distribution seen on Hα photographs. For this purpose synoptic charts of the large-scale magnetic field reconstructed by the McIntosh method have been compared with the Sun-asstar solar magnetic field observed at Stanford. We have established a close association between the Sun-as-star magnetic field and the mean magnetic field inferred from synoptic magnetic field maps. A filtering technique was applied to find correlations between the Sun-as-star and large-scale magnetic field distributions during the course of a solar cycle. The correlations found were then used to restore the Sun-as-star magnetic field and its evolution in the late 1950s and 1960s, when such measurements of the field were not being made. A stackplot display of the inferred data reveals large-scale magnetic field organization and evolution. Patterns of the Sun-as-star magnetic field during solar cycle 19 were obtained. The proposed technique can be useful for studying the solar magnetic field structure and evolution during times with no direct observations.

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 Active regions and the interplanetary magnetic field

1968 ◽  
Vol 35 ◽  
pp. 390-394
Author(s):  
John M. Wilcox ◽  
Norman F. Ness ◽  
Kenneth H. Schatten
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Large Scale ◽  
Early Stage ◽  
Active Regions ◽  
The Sun ◽  
Sector Structure ◽  
Archimedean Spiral ◽  
Spiral Angle ◽  
Scale Evolution

The relation of solar active regions to the large-scale sector structure of the interplanetary field is discussed. In the winter of 1963–64 (observed by the satellite IMP-1) the plage density was greatest in the leading portion of the sectors and lesser in the trailing portion of the sectors. The boundaries of the sectors (places at which the direction of the interplanetary magnetic field changed from toward the Sun to away from the Sun, or vice versa) were remarkably free of plages. The very fact that since the first observations in 1962 the average interplanetary field has almost always had the property of being either toward the Sun or away from the Sun (along the Archimedean spiral angle) continuously for several days must be considered in the discussion of large-scale evolution of active regions. Using the observed interplanetary magnetic field at 1 AU and a set of reasonable assumptions the magnetic configuration in the ecliptic from 0·4 AU to 1·2 AU has been reconstructed. In at least one case a pattern emerges which appears to be related to the evolution of an active region from an early stage in which the magnetic lines closely couple the preceding and following halves of the region to a later stage in which the two halves of the region are more widely separated.

scholarly journals Nature of Large-Scale Solar Magnetic Field and Complexity of HCS as Observed in Interplanetary Plasma

1990 ◽  
Vol 142 ◽  
pp. 343-344
Author(s):  
T E Girish ◽  
S R Prabhakaran Nayar
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Large Scale ◽  
Solar Magnetic Field ◽  
Solar Rotation ◽  
Solar Wind Plasma ◽  
Heliospheric Current Sheet ◽  
The North ◽  
Interplanetary Plasma ◽  
South Asymmetry

The properties of the interplanetary plasma and magnetic field near 1 AU is determined by the nature of large-scale solar magnetic field and the associated structure of the heliospheric current sheet (HCS). Magnetic multipoles often present near the solar equator affect the solar wind plasma and magnetic field (IMF) near earth's orbit. The observation of four or more IMF sectors per solar rotation and the north-south asymmetry in the HCS are observational manifestations of the influence of solar magnetic multipoles, especially the quadrupole on the interplanetary medium (Schultz, 1973; Girish and Nayar, 1988). The solar wind plasma is known to be organised around the HCS. In this work, we have investigated the possibility of inferring i) the relative dipolar and quadrupolar heliomagnetic contributions to the HCS geometry from the observation of four sector IMF structure near earth and ii) the properties of the north-south asymmetry in HCS geometry about the heliographic equator from IMF and solar wind observations near 1 AU.

Detection of a change in the North-South ratio of count rates of particles of high-energy cosmic rays during a change in the polarity of the magnetic field of the Sun

JETP Letters ◽  
2015 ◽  
Vol 101 (4) ◽  
pp. 228-231
Author(s):  
A. V. Karelin ◽  
O. Adriani ◽  
G. C. Barbarino ◽  
G. A. Bazilevskaya ◽  
R. Bellotti ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
High Energy ◽  
The Sun ◽  
High Energy Cosmic Rays ◽  
The North ◽  
The Magnetic Field
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