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 Differential emission measure analysis of hot-flare plasma from solar-maximum mission X-ray data

1984 ◽  
Vol 4 (7) ◽  
pp. 203-207 ◽  
Author(s):  
J. Jakimiec ◽  
J. Sylwester ◽  
J.R. Lemen ◽  
R. Mewe ◽  
R.D. Bentley ◽  
...  
Keyword(s):  
Solar Maximum ◽  
Emission Measure ◽  
Differential Emission Measure ◽  
Solar Maximum Mission ◽  
X Ray ◽  
Measure Analysis ◽  
Flare Plasma

scholarly journals On the Thermal Structure of the Flare-Produced Plasma

1975 ◽  
Vol 68 ◽  
pp. 187-189
Author(s):  
Ian Craig
Keyword(s):  
Thermal Structure ◽  
Emission Measure ◽  
Active Regions ◽  
Delta Function ◽  
Power Law Distribution ◽  
Differential Emission Measure ◽  
X Ray ◽  
Fitting Procedure ◽  
Bremsstrahlung Emission ◽  
Image Position

SummaryRecent flare studies have shown that soft X-ray data are not compatible with simple isothermal models of the source (Herring and Craig, 1973; Craig, 1973; Neupert et al., 1973). With this in mind, the emitting flare plasma has been represented by the temperature-emission measure distribution function, where ζ(T) is the differential emission measure (cm–3 per 106 K), T is the electron temperature in units of 106 K, T0 is a low temperature cut-off for the distribution, αi are real positive numbers, and Ai are positive coefficients determined from data (for appropriate values of T0 and αi) by a least squares fitting procedure. Such a distribution is suggested by results obtained by the present author using simple delta-function representations for ζ(T) (with n ≤ 4); these discreet multi-temperature models usually indicate that the emission measure decreases with increasing temperature. Also, as discussed by Brown (1974), a power law distribution for ζ(T) is consistent with the observed bremsstrahlung emission in the hard X-ray (> 10 keV) domain. In attempting to find a suitable form for the differential emission measure, a simple empirical function of the type assumed by Chambe (1971) for active regions was also tried, but the fit, as evidenced by the χ2 test was unsatisfactory.

scholarly journals Variations of the Coronal Radiation in X-ray Related to Coronal Holes, Active Region Loop Systems, Bright Points

1994 ◽  
Vol 143 ◽  
pp. 159-171
Author(s):  
Ester Antonucci
Keyword(s):  
Magnetic Field ◽  
Spatial Distribution ◽  
Large Scale ◽  
Coronal Holes ◽  
Active Regions ◽  
Coronal Magnetic Field ◽  
Small Scale ◽  
X Ray ◽  
Coronal Structures

The coronal features observed in X-ray emission, varying from the small-scale, short-lived bright points to the large-scale, long-lived coronal holes, are closely associated with the coronal magnetic field and its topology, and their variability depends strongly on the solar cycle. Here we discuss the spatial distribution of the coronal structures, the frequency distribution of the brightness variations in active regions, and the role of magnetic reconnection in determining the variability of the coronal features, on the basis of the new observations of the soft X-ray emission recently obtained with the Yohkoh satellite and the NIXT experiment.

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 First Determinations of Differential Emission Measure Distribution from RESIK X-ray Spectra

2004 ◽  
Vol 2004 (IAUS223) ◽  
pp. 461-462 ◽  
Author(s):  
A. K[ecedilla]pa ◽  
J. Sylwester ◽  
B. Sylwester ◽  
M. Siarkowski
Keyword(s):  
Emission Measure ◽  
Differential Emission Measure ◽  
X Ray ◽  
Measure Distribution

General Structure of the X-ray Corona

1994 ◽  
Vol 144 ◽  
pp. 69-76
Author(s):  
L. W. Acton
Keyword(s):  
Time Scales ◽  
Time Resolution ◽  
Angular Resolution ◽  
General Structure ◽  
Coronal Holes ◽  
Active Regions ◽  
X Ray ◽  
Structure Changes

AbstractX-ray images have revealed the corona to comprise four basic morphologies. In order of X-ray luminosity these structures are: (1) Bright, relatively short, X-ray loops in active regions, (2) Less bright and larger X-ray structures of the so-called quiet corona, (3) X-ray bright points, and (4) Coronal holes. The soft X-ray telescope (SXT) onYohkohprovides good angular resolution with much improved time resolution and continuity of coverage as compared to the earlier observations. In the SXT movies these structures often appear to be interacting and change appearance on time scales from seconds to weeks. Flare, flare-like, and eruptive processes continuously alter the general structure of the corona. This paper will comment on the structure, changes and heating of the X-ray corona as revealed by theYohkohobservations.

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