Protons associated with centres of solar activity and their propagation in interplanetary magnetic-field regions co-rotating with the Sun

The Pioneer-6 and Pioneer-7 space probes carried charged-particle telescopes which measure, for the first time, both the direction of arrival and differential energy spectra of protons and alpha particles. The intensity changes, directional distributions and energy spectra of proton fluxes associated with solar activity are investigated. The data were obtained in the beginning of the new solar cycle (no. 20), when it is possible to unambiguously associate proton-flux increases with specific solar active regions. The origin, possibly long-term storage, and propagation of these proton fluxes are investigated. It was observed that enhanced 0·6–13 MeV proton fluxes associated with specific active regions were present over heliographic longitude ranges as great as ~ 180°. These enhanced fluxes exhibit definite onsets and cut-offs which appear to be associated with the magnetic-sector boundaries observed by Ness on Pioneer-6. Discrete flare-produced intensity increases extending in energy to more than 50 MeV are observed, superposed on the enhanced flux. These increases displayed short transit times and short rise times. Both the enhanced and flare-produced fluxes propagate along the spiral interplanetary magnetic field from the Western hemisphere of the Sun. From these observations we are led to a model in which the magnetic fields from the active region are spread out over a longitude range of 100–180° in the solar corona. The existence of strong unidirectional anisotropies in the initial phases of flare-proton events implies that little scattering occurs between the Sun and spacecraft. However, the gradual approach to an isotropic flux at late times indicates that the decay phase is controlled by the interplanetary magnetic field.

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About the Relation Between the Limb Effect of the Redshift on the Sun and the Large-Scale Distribution of Solar activity

Symposium - International Astronomical Union ◽

10.1017/s0074180900008111 ◽

1976 ◽

Vol 71 ◽

pp. 113-118

Author(s):

P. Ambrož

Keyword(s):

Magnetic Field ◽

Solar Activity ◽

Magnetic Fields ◽

Interplanetary Magnetic Field ◽

Large Scale ◽

The Sun ◽

Limb Effect

The measurement of the magnitude of the limb effect was homogenized in time and a recurrent period of maxima of 27.8 days was found. A relation was found between the maximum values of the limb effect of the redshift, the boundaries of polarities of the interplanetary magnetic field, the characteristic large-scale distribution of the background magnetic fields and the complex of solar activity.

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Active regions and the interplanetary magnetic field

Symposium - International Astronomical Union ◽

10.1017/s007418090002180x ◽

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.

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Introducing the Sun and SEPs

Solar Energetic Particles - Lecture Notes in Physics ◽

10.1007/978-3-030-66402-2_1 ◽

2021 ◽

pp. 1-18

Author(s):

Donald V. Reames

Keyword(s):

Magnetic Field ◽

Solar Activity ◽

Solar Cycle ◽

Differential Rotation ◽

Coronal Mass Ejections ◽

Energetic Particle ◽

Solar Magnetic Field ◽

Solar Energetic Particle ◽

Active Regions ◽

The Sun

AbstractThe structure of the Sun, with its energy generation and heating, creates convection and differential rotation of the outer solar plasma. This convection and rotation of the ionized plasma generates the solar magnetic field. This field and its variation spawn all of the solar activity: solar active regions, flares, jets, and coronal mass ejections (CMEs). Solar activity provides the origin and environment for both the impulsive and gradual solar energetic particle (SEP) events. This chapter introduces the background environment and basic properties of SEP events, time durations, abundances, and solar cycle variations.

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Protons Associated with Centres of Solar Activity and their Propagation in Interplanetary Magnetic-Field Regions Co-Rotating with the Sun

Structure and Development of Solar Active Regions ◽

10.1007/978-94-011-6815-1_60 ◽

1968 ◽

pp. 403-403

Author(s):

C. Y. Fan ◽

M. Pick ◽

R. Ryle ◽

J. A. Simpson ◽

D. R. Smith

Keyword(s):

Magnetic Field ◽

Solar Activity ◽

Interplanetary Magnetic Field ◽

The Sun

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Protons associated with centers of solar activity and their propagation in interplanetary magnetic field regions corotating with the Sun

Journal of Geophysical Research Atmospheres ◽

10.1029/ja073i005p01555 ◽

1968 ◽

Vol 73 (5) ◽

pp. 1555-1582 ◽

Cited By ~ 119

Author(s):

C. Y. Fan ◽

M. Pick ◽

R. Pyle ◽

J. A. Simpson ◽

D. R. Smith

Keyword(s):

Magnetic Field ◽

Solar Activity ◽

Interplanetary Magnetic Field ◽

The Sun

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Discussion of paper by C. Y. Fan, M. Pick, R. Pyle, J. A. Simpson, and D. R. Smith, ‘Protons associated with centers of solar activity and their propagation in interplanetary magnetic field regions corotating with the Sun’

Journal of Geophysical Research Atmospheres ◽

10.1029/ja074i009p02449 ◽

1969 ◽

Vol 74 (9) ◽

pp. 2449-2451 ◽

Cited By ~ 3

Author(s):

John M. Wilcox ◽

Kenneth H. Schatten

Keyword(s):

Magnetic Field ◽

Solar Activity ◽

Interplanetary Magnetic Field ◽

The Sun

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On the scaling of waiting-time distributions of the negative IMF <i>B<sub>z</sub></i> component

Annales Geophysicae ◽

10.5194/angeo-24-2735-2006 ◽

2006 ◽

Vol 24 (10) ◽

pp. 2735-2741 ◽

Cited By ~ 16

Author(s):

R. D'Amicis ◽

R. Bruno ◽

B. Bavassano ◽

V. Carbone ◽

L. Sorriso-Valvo

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Solar Activity ◽

Solar Cycle ◽

Interplanetary Magnetic Field ◽

Power Law ◽

Waiting Time ◽

The Sun ◽

Activity Phase ◽

Solar Wind Parameters

Abstract. Statistics associated with the fluctuations in solar wind parameters show a remarkable dependence on the solar activity phase. In particular, we focus our attention on the waiting-time statistics governing the MHD fluctuations of the z-component of the interplanetary magnetic field, which are important within the framework of the Sun-Earth connections, and briefly discuss the preliminary results. Data from several spacecrafts, covering different phases of the solar cycle and different radial distances, are used. We found that propagating Alfvénic fluctuations and convected structures strongly influence the statistics which vary from quasi-Poissonian to power law.

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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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Excitation And Ionization By Auroral Protons

Australian Journal of Physics ◽

10.1071/ph660309 ◽

1966 ◽

Vol 19 (3) ◽

pp. 309 ◽

Cited By ~ 30

Keyword(s):

Magnetic Field ◽

Energy Range ◽

Pitch Angle ◽

Proton Energy ◽

Ionization Rate ◽

Energy Spectra ◽

Proton Fluxes ◽

Atmospheric Ionization ◽

The Magnetic Field

Height distributions are presented for the atmospheric ionization rate and Balmer radiation resulting from precipitation of auroral protons. These results have been computed assuming proton fluxes with several different energy spectra and pitch-angle distributions about the magnetic field, the total proton energy range being restricted to 1-1000 keY.

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