scholarly journals Coronal Magnetic Fields Deduced from Radio Methods

1993 ◽  
Vol 141 ◽  
pp. 249-257 ◽  
Author(s):  
A. Krüger ◽  
J. Hildebrandt
Keyword(s):  
Magnetic Fields ◽  
Solar Atmosphere ◽  
Active Regions ◽  
Physical Processes ◽  
Poor Knowledge ◽  
X Ray ◽  
The Poor ◽  
Coronal Magnetic Fields ◽  
Spectral Ranges ◽  
Different Levels

AbstractMajor problems of the physics of the solar atmosphere and processes of solar activity are due to the poor knowledge of the magnetic fields outside the photosphere. Unique methods to determine magnetic fields in the corona and chromosphere make use of radio observations in close connection with information obtained in other spectral ranges e.g. the optical and X-ray regions. Based on relevant emission and propagation processes, the basic radio methods providing information on the parent magnetic fields are summarized. Signatures in the microwave and meter wave regions are used to derive magnetic field parameters at different levels in the solar atmosphere of active regions during quiet and flaring conditions. Implications on fine and gross structures are briefly discussed and consequences on acting physical processes mentioned.

scholarly journals The Magnetic Fields at Different Levels in the Active Regions of the Solar Atmosphere

1971 ◽  
Vol 43 ◽  
pp. 223-230 ◽  
Author(s):  
T. T. Tsap
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Atmosphere ◽  
Longitudinal Magnetic Field ◽  
Active Regions ◽  
Close Correlation ◽  
Crimean Astrophysical Observatory ◽  
Different Depths ◽  
Different Levels ◽  
Made In

The strengths of the longitudinal magnetic fields recorded at different depths of active regions with a double magnetograph of the Crimean Astrophysical Observatory are compared.The recordings of the magnetic fields were made in the lines Fe Iλ5250Å, Ca Iλ6103Å, Na I D1, BIIλ4554Å, Mg Iλ5184Å, Hα, Hγ, Hδ.It is shown, that there is a close correlation between the longitudinal magnetic field at different levels.

Influence of Magnetic Fields on Solar Hydrodynamics: Experimental Results

1977 ◽  
Vol 36 ◽  
pp. 143-180 ◽  
Author(s):  
J.O. Stenflo
Keyword(s):  
Solar Activity ◽  
Energy Balance ◽  
Magnetic Fields ◽  
Solar Atmosphere ◽  
General Problem ◽  
Solar Rotation ◽  
Active Regions ◽  
Physical Conditions ◽  
Dynamic Phenomena

It is well-known that solar activity is basically caused by the Interaction of magnetic fields with convection and solar rotation, resulting in a great variety of dynamic phenomena, like flares, surges, sunspots, prominences, etc. Many conferences have been devoted to solar activity, including the role of magnetic fields. Similar attention has not been paid to the role of magnetic fields for the overall dynamics and energy balance of the solar atmosphere, related to the general problem of chromospheric and coronal heating. To penetrate this problem we have to focus our attention more on the physical conditions in the ‘quiet’ regions than on the conspicuous phenomena in active regions.

scholarly journals Observations of magnetic and kinetic helicity proxies

2012 ◽  
Vol 8 (S294) ◽  
pp. 13-24
Author(s):  
Hongqi Zhang
Keyword(s):  
Magnetic Field ◽  
Velocity Field ◽  
Magnetic Fields ◽  
Solar Atmosphere ◽  
Active Regions ◽  
Solar Dynamo ◽  
Magnetic Helicity ◽  
Vector Magnetograms ◽  
Topological Configuration ◽  
The Relationship

AbstractThe helicity is important to present the basic topological configuration of magnetic field in solar atmosphere. The distribution of magnetic helicity in solar atmosphere is presented by means of the observational (vector) magnetograms. As the kinetic helicity in the solar subatmosphere can be inferred from the velocity field based on the technique of the helioseismology and used to compare with the magnetic helicity in the solar atmosphere, the observational helicities provide the important chance for the confirmation on the generation of magnetic fields in the subatmosphere and solar dynamo models also. In this paper, we present the observational magnetic and kinetic helicity in solar active regions and corresponding questions, except the relationship with solar eruptive phenomena.

Numerical Short-Term Solar Activity Forecasting

2017 ◽  
Vol 13 (S335) ◽  
pp. 243-249 ◽  
Author(s):  
Huaning Wang ◽  
Yihua Yan ◽  
Han He ◽  
Xin Huang ◽  
Xinghua Dai ◽  
...  
Keyword(s):  
Solar Activity ◽  
Magnetic Fields ◽  
Solar Atmosphere ◽  
Magnetic Energy ◽  
Three Dimensional ◽  
Active Regions ◽  
Short Term ◽  
Solar Active Regions ◽  
Solar Eruptions ◽  
Dimensional Reconstruction

AbstractIt is well known that the energy for solar eruptions comes from magnetic fields in solar active regions. Magnetic energy storage and dissipation are regarded as important physical processes in the solar corona. With incomplete theoretical modeling for eruptions in the solar atmosphere, activity forecasting is mainly supported with statistical models. Solar observations with high temporal and spatial resolution continuously from space well describe the evolution of activities in the solar atmosphere, and combined with three dimensional reconstruction of solar magnetic fields, makes numerical short-term (within hours to days) solar activity forecasting possible. In the current report, we propose the erupting frequency and main attack direction of solar eruptions as new forecasts and present the prospects for numerical short-term solar activity forecasting based on the magnetic topological framework in solar active regions.

scholarly journals Coronal Magnetic Fields of Algol Binaries from Microwave Spectra

1991 ◽  
Vol 130 ◽  
pp. 498-500
Author(s):  
G. Umana ◽  
C. Trigilio ◽  
R. M. Hjellming ◽  
S. Catalano ◽  
M. Rodonò
Keyword(s):  
Magnetic Fields ◽  
Radio Emission ◽  
Mass Exchange ◽  
Thermal Emission ◽  
Magnetic Activity ◽  
Microwave Emission ◽  
X Ray ◽  
Coronal Magnetic Fields ◽  
Hydrodynamic Processes ◽  
Hot Corona

Algol-type binaries are basically known to undergo hydrodynamic processes related to mass exchange between components. Recent observations on radio, X-ray emission and flare-like events have raised the question of possible magnetic activity in the secondary component of these systems (Hall, 1989).From a microwave emission survey we have shown that the radio emission from Algol systems cannot be accounted for by thermal emission from an hot corona (T ≥ 107K) and that their radio luminosities compare very well with those of the magnetically active RS CVn systems (Umana et al., 1990).

scholarly journals Hard X-Ray Imaging Observations by Yohkoh of the 15 November, 1991 Flare

1993 ◽  
Vol 141 ◽  
pp. 258-262
Author(s):  
Taro Sakao
Keyword(s):  
Magnetic Fields ◽  
Energy Release ◽  
Impulsive Phase ◽  
Time Profile ◽  
X Rays ◽  
X Ray ◽  
Precipitation Model ◽  
X Ray Imaging ◽  
Coronal Magnetic Fields ◽  
The Individual

AbstractWe present hard X-ray imaging observations by Yohkoh of the 15 November, 1991 flare. The pre-impulsive and the impulsive phase observations are summarized as follows: (1) Hard X-ray sources in the precursor (or pre–impulsive) phase appear in a much wider area compared with the impulsive phase sources and they show clear evolution just before the onset of the impulsive phase. This suggests that some global re-structuring of coronal magnetic fields led to the impulsive energy release. (2) In the impulsive phase, at the peaks of the individual spikes of the time profile, the bulk of the hard X-ray emission (above 20 keV) originates from the footpoints of the flaring loop. At the valleys between the spikes, X-rays below 30 keV are emitted from near the loop top, while higher energy ones (above 30 keV) are still emitted from the footpoints. Such behavior of hard X-ray sources can be explained by the partial precipitation model.

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