Properties of solar coronal active regions deduced from X-ray line spectra

1987 ◽  
Vol 322 ◽  
pp. 512 ◽  
Author(s):  
D. L. McKenzie
Keyword(s):  
Active Regions ◽  
X Ray ◽  
Solar Coronal

scholarly journals Association of X-Ray Flares with Solar Coronal Active Regions

1975 ◽  
Vol 68 ◽  
pp. 183-183
Author(s):  
P. R. Sengupta
Keyword(s):  
Solar Activity ◽  
Active Regions ◽  
X Ray ◽  
Solar Coronal

SummaryIt is known that the flare component of solar X-ray emission is sensitive to the level of solar activity. The location of the X-ray flaring region is not directly known but can be inferred from the location of the associated Hα flare. A detailed study of more than 4000 solar X-ray flares recorded by UI and the NRL detectors during past eight years has shown that 85% of these flares definitely occurred in the active regions. For the rest 15% no definite conclusion was possible because either Hα flare data was not available or no Hα flare was reported within ± 15 min of these X-ray flares.

Investigating the Effect of Opacity in Soft X‐Ray Spectral Lines Emitted by Solar Coronal Active Regions

1997 ◽  
Vol 477 (1) ◽  
pp. 509-515 ◽  
Author(s):  
J. T. Schmelz ◽  
J. L. R. Saba ◽  
J. C. Chauvin ◽  
K. T. Strong
Keyword(s):  
Active Regions ◽  
Spectral Lines ◽  
X Ray ◽  
Solar Coronal

Structure and Development of Quiet Loops in the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 163-168 ◽  
Author(s):  
E. Hiei
Keyword(s):  
Solar Corona ◽  
Active Regions ◽  
Time Behavior ◽  
Rapid Variability ◽  
X Ray ◽  
Quiet Region ◽  
Flare Loops ◽  
Emission Change ◽  
Solar Coronal

AbstractSolar coronal features seen in X-ray emission change on two different timescales: a) flare loops and transient brightenings in active regions show a rapid variability, b) quiet region loops are quasi-steady and change only slowly with time. This different time behavior has been analyzed on the basis of Yohkoh SXT observations and we report here on the results from our analysis, mainly focussing on quiet loop variability.

scholarly journals Interpretation of the X-Ray Spectra of Solar Active Regions

1975 ◽  
Vol 68 ◽  
pp. 73-100 ◽  
Author(s):  
Arthur B. C. Walker
Keyword(s):  
Transition Region ◽  
Rate Constant ◽  
Active Regions ◽  
Temperature Structure ◽  
Spectroscopic Techniques ◽  
Density Structure ◽  
Coronal Temperature ◽  
X Ray ◽  
Euv Spectrum

This paper presents a review of recent analytical studies of the coronal X-ray spectrum below 25 Å. The techniques used to compute the theoretical coronal spectrum, and the currently available atomic rate constant data are reviewed first. Spectroscopic techniques which have been proposed for the determination of coronal temperature and density structure, and the results derived from their application to coronal spectra are also reviewed.A number of coronal models based on X-ray observations have been developed recently, and the coronal temperature structure and composition predicted by these models is discussed, and compared with models of the corona and transition region derived from studies of the solar EUV spectrum.

scholarly journals X-Ray Spectra of Solar Active Regions

1975 ◽  
Vol 68 ◽  
pp. 45-64 ◽  
Author(s):  
John H. Parkinson
Keyword(s):  
Spectral Resolution ◽  
Active Regions ◽  
X Ray ◽  
Quantitative Theory ◽  
Great Progress ◽  
Solar Active Regions ◽  
Cascading Processes ◽  
Weak Satellite

The last few years have seen great progress in our understanding of X-ray spectra of solar active regions. This paper demonstrates both the usefulness and the limitations of the techniques, both scientific and instrumental, that have recently become available. Improvements in spectral resolution led to the discovery of weak satellite lines to helium-like ions; the quantitative theory for these lines is also discussed. The observed intensities of the Fe XVII lines are also investigated and found to be in agreement with calculations that allow for cascading processes.

scholarly journals Statistical Properties of Magnetic Separators in Model Active Regions

2000 ◽  
Vol 195 ◽  
pp. 443-444
Author(s):  
B. T. Welsch ◽  
D. W. Longcope
Keyword(s):  
Active Region ◽  
Solar Corona ◽  
Magnetic Reconnection ◽  
First Principles ◽  
Magnetic Charge ◽  
Active Regions ◽  
Heating Rates ◽  
X Ray ◽  
Field Lines ◽  
Charge Topology

“Transient brightenings” (or “microflares”) regularly deposit 1027 ergs of energy in the solar corona, and account for perhaps 20% of the active corona's power (Shimizu 1995). We assume these events correspond to episodes of magnetic reconnection along magnetic separators in the solar corona. Using the techniques of magnetic charge topology, we model active region fields as arising from normally distributed collections of “magnetic charges”, point-like sources/sinks of flux (or field lines). Here, we present statistically determined separator (X-ray loop) lengths, derived from first principles. We are in the process of statistical calculations of heating rates due to reconnection events along many separators.

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