scholarly journals Localized magnetic field structures and their boundaries in the near-Sun solar wind from Parker Solar Probe measurements

2020 ◽  
Author(s):  
Vladimir Krasnoselskikh ◽  
Keyword(s):  
Solar Wind ◽  
Radial Component ◽  
Plasma Pressure ◽  
Small Scale ◽  
The Sun ◽  
Ion Plasma ◽  
Scale Structures ◽  
Localized Magnetic Field ◽  
Probe Measurements ◽  
Small Scale Structures

<p>One of the most striking discoveries made by Parker Solar Probe during its first three encounters with the Sun is the presence of a multitude of relatively small-scale structures that stand out as sudden deflections of the magnetic. They were named “switchbacks” since some of them show up the full reversal of the radial component of the magnetic field and return to “regular” solar wind conditions. We carried out an analysis of three typical switchback structures having slightly different characteristics: I. Alfv´enic structures, where the variations of the magnetic field components take place conserving the magnitude of the magnetic field constant; II. Compressional, where the magnetic field magnitude varies together with changes of the components of the magnetic field; III. Structures manifesting full reversal of the magnetic field, they may be presumably similar to Alfv´enic, but they are some extremal class of “switchback structures”. We analyzed the properties of the magnetic field of these structures and the characteristics of their boundaries. Our observations and analysis lead to the conclusion that the structures represent localized magnetic field tubes moving with respect to surrounding plasma. The very important characteristic of these tubes consists of the existence of a relatively narrow boundary layer on the surface of the tube that accommodates flowing currents. These currents supposedly closed on the surface of the structure, and typically they have comparable azimuthal and the tube axes aligned components. These currents are supported by the presence of the effective electric field ensured by quite strong gradients of the density, and ion plasma pressure. The ion beta is typically larger than one inside the structure, and less than one outside. Another important feature is an electromagnetic wave accommodated on the surface of the structure. Its role consists in assistance to particles in carrying currents, to electrons parallel to magnetic field, and perpendicular to field to ions.</p>

scholarly journals Diamagnetic structures as a basis of quasi-stationary slow solar wind

2019 ◽  
Vol 5 (3) ◽  
pp. 36-49
Author(s):  
Виктор Еселевич ◽  
Viktor Eselevich
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Plasma Density ◽  
Neutral Line ◽  
Angular Size ◽  
Radial Component ◽  
Slow Solar Wind ◽  
Small Scale ◽  
The Sun ◽  
Streamer Belt

The results presented in this review reflect the fundamentals of the modern understanding of the nature of the structure of the slow solar wind (SW) along the entire length from the Sun to the Earth's orbit. It is known that the source of the slow quasi-stationary SW on the Sun is the belt and the chains of coronal streamers The streamer belt encircles the entire Sun as a wave-like surface (skirt), representing a sequence of pairs of rays with increased brightness (plasma density) or two lines of rays located close to each other. Neutral line of the radial component of the solar global magnetic field goes along the belt between the rays of each of these pairs. The streamer belt extends in the heliosphere is as the heliospheric plasma sheet (HPS). Detailed analysis of data from Wind and IMP-8 satellites showed that HPS sections on the Earth orbit are registered as a sequence of diamagnetic tubes with high density plasma and low interplanetary magnetic field. They represent an extension of rays with increased brightness of the streamer belt near the Sun. Their angular size remains the same over the entire way from the Sun to the Earth's orbit. Each HPS diamagnetic tube has a fine internal structure on several scales, or fractality. In other words, diamagnetic tube is a set of nested diamagnetic tubes, whose angular size can vary by almost two orders of magnitude. These sequences of diamagnetic tubes that form the base of slow SW on the Earth's orbit has a more general name — diamagnetic structures (DS). In the final part of this article, a comparative analysis of several events was made, based on the results of this review. He made it possible to find out the morphology and nature of the origin of the new term “diamagnetic plasmoids” SW (local amplifications of plasma density), which appeared in several articles published during 2012–2018. The analysis carried out at the end of this article, for the first time, showed that the diamagnetic plasmoids SW are the small-scale component of the fractal diamagnetic structures of the slow SW, considered in this review.

scholarly journals Diamagnetic structures as a basis of quasi-stationary slow solar wind

2019 ◽  
Vol 5 (3) ◽  
pp. 29-41 ◽  
Author(s):  
Виктор Еселевич ◽  
Viktor Eselevich
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Plasma Density ◽  
Neutral Line ◽  
Angular Size ◽  
Radial Component ◽  
Slow Solar Wind ◽  
Small Scale ◽  
The Sun ◽  
Streamer Belt

The results presented in this review reflect the fundamentals of the modern understanding of the nature of the structure of the slow solar wind (SW) along the entire length from the Sun to the Earth's orbit. It is known that the source of the slow quasi-stationary SW on the Sun is the belt and the chains of coronal streamers The streamer belt encircles the entire Sun as a wave-like surface (skirt), representing a sequence of pairs of rays with increased brightness (plasma density) or two lines of rays located close to each other. Neutral line of the radial component of the solar global magnetic field goes along the belt between the rays of each of these pairs. The streamer belt extends in the heliosphere is as the heliospheric plasma sheet (HPS). Detailed analysis of data from Wind and IMP-8 satellites showed that HPS sections on the Earth orbit are registered as a sequence of diamagnetic tubes with high density plasma and low interplanetary magnetic field. They represent an extension of rays with increased brightness of the streamer belt near the Sun. Their angular size remains the same over the entire way from the Sun to the Earth's orbit. Each HPS diamagnetic tube has a fine internal structure on several scales, or fractality. In other words, diamagnetic tube is a set of nested diamagnetic tubes, whose angular size can vary by almost two orders of magnitude. These sequences of diamagnetic tubes that form the base of slow SW on the Earth's orbit has a more general name — diamagnetic structures (DS). In the final part of this article, a comparative analysis of several events was made, based on the results of this review. He made it possible to find out the morphology and nature of the origin of the new term “diamagnetic plasmoids” SW (local amplifications of plasma density), which appeared in several articles published during 2012–2018. The analysis carried out at the end of this article, for the first time, showed that the diamagnetic plasmoids SW are the small-scale component of the fractal diamagnetic structures of the slow SW, considered in this review.

scholarly journals Heliospheric current sheet inclinations at Venus and Earth

1999 ◽  
Vol 17 (5) ◽  
pp. 642-649 ◽  
Author(s):  
G. Ma ◽  
K. Marubashi ◽  
T. Maruyama
Keyword(s):  
Solar Wind ◽  
Magnetic Fields ◽  
Current Sheet ◽  
Solar Maximum ◽  
Heliospheric Current Sheet ◽  
Small Scale ◽  
Sector Boundary ◽  
Scale Structures ◽  
Transient Structures ◽  
Small Scale Structures

Abstract. We investigate the inclinations of heliospheric current sheet at two sites in interplanetary space, which are generated from the same solar source. From the data of solar wind magnetic fields observed at Venus (0.72 AU) and Earth (1 AU) during December 1978-May 1982 including the solar maximum of 1981, 54 pairs of candidate sector boundary crossings are picked out, of which 16 pairs are identified as sector boundaries. Of the remainder, 12 pairs are transient structures both at Venus and Earth, and 14 pairs are sector boundaries at one site and have transient structures at the other site. It implies that transient structures were often ejected from the coronal streamer belt around the solar maximum. For the 16 pairs of selected sector boundaries, we determine their normals by using minimum variance analysis. It is found that most of the normal azimuthal angles are distributed between the radial direction and the direction perpendicular to the spiral direction both at Venus and Earth. The normal elevations tend to be smaller than ~ 45° with respect to the solar equatorial plane, indicating high inclinations of the heliospheric current sheet, in particular at Earth. The larger scatter in the azimuth and elevation of normals at Venus than at Earth suggests stronger effects of the small-scale structures on the current sheet at 0.72 AU than at 1 AU. When the longitude difference between Venus and Earth is small (<40° longitudinally), similar or the same inclinations are generally observed, especially for the sector boundaries without small-scale structures. This implies that the heliospheric current sheet inclination tends to be maintained during propagation of the solar wind from 0.72 AU to 1 AU. Detailed case studies reveal that the dynamic nature of helmet streamers causes variations of the sector boundary structure.Key words. Interplanetary physics (interplanetary magnetic fields; sources of solar wind)

Exploring Coronal Structures with SOHO

2000 ◽  
Vol 179 ◽  
pp. 403-406
Author(s):  
M. Karovska ◽  
B. Wood ◽  
J. Chen ◽  
J. Cook ◽  
R. Howard
Keyword(s):  
Solar Corona ◽  
Image Enhancement ◽  
Coronal Mass Ejections ◽  
Dynamical Evolution ◽  
Small Scale ◽  
Low Contrast ◽  
Contrast Structures ◽  
Scale Structures ◽  
Small Scale Structures ◽  
Coronal Structures

AbstractWe applied advanced image enhancement techniques to explore in detail the characteristics of the small-scale structures and/or the low contrast structures in several Coronal Mass Ejections (CMEs) observed by SOHO. We highlight here the results from our studies of the morphology and dynamical evolution of CME structures in the solar corona using two instruments on board SOHO: LASCO and EIT.

scholarly journals Observational aspects of prominence oscillations

2007 ◽  
Vol 3 (S247) ◽  
pp. 152-157 ◽  
Author(s):  
Oddbjørn Engvold
Keyword(s):  
Magnetic Structure ◽  
Numerical Models ◽  
Small Scale ◽  
Solar Prominences ◽  
Scale Structures ◽  
Oscillations And Waves ◽  
Available Information ◽  
Small Scale Structures

AbstractSeismology has become a powerful tool in studies of the magnetic structure of solar prominences and filaments. Reversely, analytical and numerical models are guided by available information about the spatial and thermodynamical structure of these enigmatic structures. The present invited paper reviews recent observational results on oscillations and waves as well as details about small-scale structures and dynamics of prominences and filaments.

scholarly journals Detailed maps of interstellar clouds in front of ω Centauri: small-scale structures in the Galactic disc-halo interface

2009 ◽  
Vol 399 (1) ◽  
pp. 195-208 ◽  
Author(s):  
Jacco Th. van Loon ◽  
Keith T. Smith ◽  
Iain McDonald ◽  
Peter J. Sarre ◽  
Stephen J. Fossey ◽  
...  
Keyword(s):  
Small Scale ◽  
Galactic Disc ◽  
Interstellar Clouds ◽  
Scale Structures ◽  
Small Scale Structures
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