scholarly journals A comparison of the temperature and emission measure of X-ray active regions with coronal magnetic fields

Solar Physics ◽  
1979 ◽  
Vol 63 (1) ◽  
pp. 157-164 ◽  
Author(s):  
J. B. Burl ◽  
R. G. Teske ◽  
E. B. Mayfield
Keyword(s):  
Magnetic Fields ◽  
Emission Measure ◽  
Active Regions ◽  
X Ray ◽  
Coronal Magnetic Fields

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 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.

scholarly journals Goals for the Application of High-Resolution X-ray Spectroscopy to the Diagnosis of Stellar Coronal Plasmas

1990 ◽  
Vol 115 ◽  
pp. 94-109 ◽  
Author(s):  
Jeffrey L. Linsky
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
Transient Flow ◽  
Emission Measure ◽  
Active Regions ◽  
High Sensitivity ◽  
High Spectral Resolution ◽  
Spectral Features ◽  
Signal To Noise ◽  
X Ray

AbstractI provide examples of how high-resolution x-ray spectra may be used to determine the temperature and emission measure distributions, electron densities, steady and transient flow velocities, and location of active regions in stellar coronae. For each type of measurement I estimate the minimum spectral resolution required to resolve the most useful spectral features. In general, high sensitivity is required to obtain sufficient signal-to-noise to exploit the high spectral resolution. Although difficult, each measurement should be achievable with the instrumentation proposed for AXAF.

scholarly journals Estimation of Magnetic Field Strength from Enhanced Solar Radio Emission

1994 ◽  
Vol 47 (6) ◽  
pp. 811 ◽  
Author(s):  
SBSS Sarma
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Radio Emission ◽  
Solar Radio ◽  
Active Regions ◽  
Shock Velocity ◽  
Solar Radio Emission ◽  
Type I ◽  
Radio Noise ◽  
Coronal Magnetic Fields

The manifestation of solar activity on radio noise records at 28.6 MHz is discussed with special emphasis on Type-I noise storms and the associated coronal magnetic fields above the active regions in time. Magnetic fields are estimated, assuming that the Type-I radio emission at decametre wavelengths is due to shock waves, by making use of the observed shock velocity. The results are comparable with the existing estimates.

scholarly journals Overview of XRT performance and first results

2007 ◽  
Vol 3 (S247) ◽  
pp. 326-336
Author(s):  
Antonia Savcheva ◽  
Keyword(s):  
Fine Structure ◽  
Coronal Holes ◽  
Emission Measure ◽  
Active Regions ◽  
Potential Fields ◽  
Differential Emission Measure ◽  
Short Introduction ◽  
X Ray ◽  
First Results ◽  
Measure Analysis

AbstractIn this review we present a short introduction to the X-ray Telescope on Hinode. We discuss its capabilities and new features and compare it with Yohkoh SXT. We also discuss some of the first results that include observations of X-ray jets in coronal holes, shear change in flares, sigmoid eruptions and evolution, application of filter ratios and differential emission measure analysis, structure of active regions, fine structure of X-ray bright points, and modeling non-potential fields around filaments. Finally, we describe how XRT works with other ground and space-based instrumentation, in particular with TRACE, EIS, SOT, and SOLIS.

scholarly journals Filament Chirality: A Link Between Fine-Scale and Global Patterns

1998 ◽  
Vol 167 ◽  
pp. 419-429 ◽  
Author(s):  
Sara F. Martin
Keyword(s):  
Magnetic Fields ◽  
Large Scale ◽  
Magnetic System ◽  
Active Regions ◽  
X Ray ◽  
Physical Phenomena ◽  
Magnetic Plasma ◽  
The Magnetic Field ◽  
Opposite Helicity ◽  
Dominant Direction

AbstractSolar features that exhibit chirality are: fibril patterns in filament channels, filaments, coronal arcades over filaments, superpenumbral fibrils exterior to sunspots, whole active regions observed with magnetographs, some large-scale X-ray structures, and interplanetary magnetic plasma clouds originating from coronal mass ejections. Their signatures of chirality are briefly reviewed; some details are mentioned to further show relationships which link all of the chirality patterns into a single framework. The helicity of solar magnetic fields is the evident physical phenomena which finks each of the seven features to each other and into a broader framework. The chirality system, viewed as a whole magnetic system, reveals: (1) a consistent rotational configuration of the dominant direction of the magnetic field with height of features within and over filament channels from the photosphere to the highest part of the solar corona, and (2) the prominence cavity as a unique space between magnetic fields of opposite helicity.

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