Small-scale magnetic structures on the Sun

1989 ◽  
Vol 1 (1) ◽  
pp. 3-48 ◽  
Author(s):  
J. O. Stenflo
Keyword(s):  
Small Scale ◽  
The Sun ◽  
Magnetic Structures

scholarly journals Quasi-periodic oscillations of small-scale magnetic structures and a specific method for measuring the differential rotation of the Sun

2019 ◽  
Vol 5 (1) ◽  
pp. 4-12
Author(s):  
Иван Живанович ◽  
Ivan Zhivanovich ◽  
Александр Риехокайнен ◽  
Aleksandr Riehokainen ◽  
Александр Соловьев ◽  
...  
Keyword(s):  
Fourier Analysis ◽  
Differential Rotation ◽  
Rotation Curve ◽  
Angular Resolution ◽  
Small Scale ◽  
Specific Method ◽  
The Sun ◽  
Periodic Oscillations ◽  
Magnetic Structures ◽  
Good Agreement

The SDO/HMI data with an angular resolution of 1 arcsec have been used to explore the differential rotation on the Sun, using an original “p2p” effect on the basis of the movement of small-scale magnetic structures in the photosphere of the Sun. It is shown that a stable p2p artifact inherent in the SDO/HMI data can be an effective tool for measuring the speed of various tracers on the Sun. In particular, in combination with the Fourier analysis, it allows us to investigate the differential rotation of the Sun at various latitudes. The differential rotation curve obtained from the SDO/HMI magnetograms by this method is in good agreement with the curves obtained earlier from ground-based observations.

scholarly journals Quasi-periodic oscillations of small-scale magnetic structures and a specific method for measuring the differential rotation of the Sun

2019 ◽  
pp. 3-10
Author(s):  
Иван Живанович ◽  
Ivan Zhivanovich ◽  
Александр Риехокайнен ◽  
Alexandr Riehokainen ◽  
Александр Соловьев ◽  
...  
Keyword(s):  
Fourier Analysis ◽  
Differential Rotation ◽  
Rotation Curve ◽  
Angular Resolution ◽  
Small Scale ◽  
Specific Method ◽  
The Sun ◽  
Periodic Oscillations ◽  
Magnetic Structures ◽  
Good Agreement

The SDO/HMI data with an angular resolution of 1 arcsec have been used to explore the differential rotation on the Sun, using an original “p2p” effect on the basis of the movement of small-scale magnetic structures in the photosphere of the Sun. It is shown that a stable p2p artifact inherent in the SDO/HMI data can be an effective tool for measuring the speed of various tracers on the Sun. In particular, in combination with the Fourier analysis, it allows us to investigate the differential rotation of the Sun at various latitudes. The differential rotation curve obtained from the SDO/HMI magnetograms by this method is in good agreement with the curves obtained earlier from ground-based observations.

scholarly journals On the fractal dimension of small-scale magnetic structures in the Sun

2003 ◽  
Vol 409 (3) ◽  
pp. 1127-1134 ◽  
Author(s):  
K. Janßen ◽  
A. Vögler ◽  
F. Kneer
Keyword(s):  
Fractal Dimension ◽  
Small Scale ◽  
The Sun ◽  
Magnetic Structures

scholarly journals What scatter-hoarding animals have taught us about small-scale navigation

2010 ◽  
Vol 365 (1542) ◽  
pp. 901-914 ◽  
Author(s):  
Kristy L. Gould ◽  
Debbie M. Kelly ◽  
Alan C. Kamil
Keyword(s):  
Future Research ◽  
Small Scale ◽  
The Sun ◽  
Scatter Hoarding ◽  
Geometric Properties ◽  
Cue Use ◽  
Unique System ◽  
Spatial Locations

Many animals use cues for small-scale navigation, including beacons, landmarks, compasses and geometric properties. Scatter-hoarding animals are a unique system to study small-scale navigation. They have to remember and relocate many individual spatial locations, be fairly accurate in their searching and have to remember these locations for long stretches of time. In this article, we review what is known about cue use in both scatter-hoarding birds and rodents. We discuss the importance of local versus global cues, the encoding of bearings and geometric rules, the use of external compasses such as the Sun and the influence of the shape of experimental enclosures in relocating caches or hidden food. Scatter-hoarding animals are highly flexible in how and what they encode. There also appear to be differences in what scatter-hoarding birds and rodents encode, as well as what scatter-hoarding animals in general encode compared with other animals. Areas for future research with scatter-hoarding animals are discussed in light of what is currently known.

scholarly journals How to make the Sun look less like the Sun and more like a star?

2016 ◽  
Vol 12 (S328) ◽  
pp. 237-239
Author(s):  
A. A. Vidotto
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Vector Fields ◽  
Radial Component ◽  
Field Vector ◽  
Small Scale ◽  
General Context ◽  
The Sun ◽  
Flux Transport ◽  
Large Scale Magnetic Field

AbstractSynoptic maps of the vector magnetic field have routinely been made available from stellar observations and recently have started to be obtained for the solar photospheric field. Although solar magnetic maps show a multitude of details, stellar maps are limited to imaging large-scale fields only. In spite of their lower resolution, magnetic field imaging of solar-type stars allow us to put the Sun in a much more general context. However, direct comparison between stellar and solar magnetic maps are hampered by their dramatic differences in resolution. Here, I present the results of a method to filter out the small-scale component of vector fields, in such a way that comparison between solar and stellar (large-scale) magnetic field vector maps can be directly made. This approach extends the technique widely used to decompose the radial component of the solar magnetic field to the azimuthal and meridional components as well, and is entirely consistent with the description adopted in several stellar studies. This method can also be used to confront synoptic maps synthesised in numerical simulations of dynamo and magnetic flux transport studies to those derived from stellar observations.

scholarly journals Small Scale Solar Magnetic Fields: Theory

1977 ◽  
Vol 4 (2) ◽  
pp. 241-250 ◽  
Author(s):  
N. O. Weiss
Keyword(s):  
Magnetic Fields ◽  
Field Strength ◽  
Solar Physics ◽  
Small Scale ◽  
The Sun ◽  
Solar Magnetic Fields ◽  
Solar Granulation ◽  
The Past ◽  
Maximum Field Strength ◽  
Maximum Field

One of the most exciting developments in solar physics over the past eight years has been the success of ground based observers in resolving features with a scale smaller than the solar granulation. In particular, they have demonstrated the existence of intense magnetic fields, with strengths of up to about 1600G. Harvey (1976) has just given an excellent summary of these results.In solar physics, theory generally follows observations. Inter-granular magnetic fields had indeed been expected but their magnitude came as a surprise. Some problems have been discussed in previous reviews (Schmidt, 1968, 1974; Weiss, 1969; Parker, 1976d; Stenflo, 1976) and the new observations have stimulated a flurry of theoretical papers. This review will be limited to the principal problems raised by these filamentary magnetic fields. I shall discuss the interaction of magnetic fields with convection in the sun and attempt to answer such questions as: what is the nature of the equilibrium in a flux tube? how are the fields contained? what determines their stability? how are such strong fields formed and maintained? and what limits the maximum field strength?

MHD and Ion Kinetic Waves in Field-aligned Flows Observed by Parker Solar Probe

2021 ◽  
Vol 922 (2) ◽  
pp. 188
Author(s):  
L.-L. Zhao ◽  
G. P. Zank ◽  
J. S. He ◽  
D. Telloni ◽  
L. Adhikari ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Whistler Wave ◽  
Spectral Energy ◽  
Small Scale ◽  
The Sun ◽  
Fast Mode ◽  
Magnetic Fluctuations ◽  
Background Magnetic Field ◽  
Ion Cyclotron

Abstract Parker Solar Probe (PSP) observed predominately Alfvénic fluctuations in the solar wind near the Sun where the magnetic field tends to be radially aligned. In this paper, two magnetic-field-aligned solar wind flow intervals during PSP’s first two orbits are analyzed. Observations of these intervals indicate strong signatures of parallel/antiparallel-propagating waves. We utilize multiple analysis techniques to extract the properties of the observed waves in both magnetohydrodynamic (MHD) and kinetic scales. At the MHD scale, outward-propagating Alfvén waves dominate both intervals, and outward-propagating fast magnetosonic waves present the second-largest contribution in the spectral energy density. At kinetic scales, we identify the circularly polarized plasma waves propagating near the proton gyrofrequency in both intervals. However, the sense of magnetic polarization in the spacecraft frame is observed to be opposite in the two intervals, although they both possess a sunward background magnetic field. The ion-scale plasma wave observed in the first interval can be either an inward-propagating ion cyclotron wave (ICW) or an outward-propagating fast-mode/whistler wave in the plasma frame, while in the second interval it can be explained as an outward ICW or inward fast-mode/whistler wave. The identification of the exact kinetic wave mode is more difficult to confirm owing to the limited plasma data resolution. The presence of ion-scale waves near the Sun suggests that ion cyclotron resonance may be one of the ubiquitous kinetic physical processes associated with small-scale magnetic fluctuations and kinetic instabilities in the inner heliosphere.

II. Spots and Intense Flux Tubes

1988 ◽  
Vol 20 (1) ◽  
pp. 58-63
Author(s):  
J.C. Henoux
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
High Resolution ◽  
Solar Magnetic Field ◽  
Solar Physics ◽  
Small Scale ◽  
The Sun ◽  
Flux Tubes ◽  
Flux Concentration ◽  
Scientific Meetings

The development of research on starspots, stellar activity, and the suspected relationship between coronal heating and magnetic field have reenforced the interest of the study of the solar magnetic field and the study of the associated thermodynamic structures. Several proceedings of scientific meetings appeared from 1984 to 1987 (Measurements of Solar Vector Magnetic Fields, 1985 (I); The Hydrodynamics of the Sun, 1984 (II); High Resolution in Solar Physics, 1985 (III); Theoritical Problems in High Resolution Solar Physics, 1985 (IV); Small Scale Magnetic Flux Concentration in the Solar Atmosphere, 1986 (V)). The finding that the solar irradiance in affected by solar activity has renewed interest in photometry of sunspots and faculae. Sunspots have been used for investigating solar differential and meridional motions. Some results are also found in Section III.

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