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.

scholarly journals Chandra Studies of Supernova Remnants and Pulsars

2001 ◽  
Vol 205 ◽  
pp. 358-365
Author(s):  
Patrick Slane ◽  
John P. Hughes ◽  
Cara E. Rakowski ◽  
David N. Burrows ◽  
John A. Nousek ◽  
...  
Keyword(s):  
Time Resolution ◽  
Supernova Remnants ◽  
Angular Resolution ◽  
Fast Time ◽  
X Ray ◽  
Spatially Resolved ◽  
Unique Capability

With sub-arcsecond angular resolution accompanied by fast time resolution and spatially resolved spectral capabilities, the Chandra X-ray Observatory provides a unique capability for the study of supernova remnants (SNRs) and pulsars. Though in its relative infancy, Chandra has already returned stunning images of SNRs which reveal the distribution of ejecta synthesized in the stellar explosions, the distinct properties of the forward and reverse shocks, and the presence of faint shells surrounding compact remnants. Pulsar observations have uncovered jet features as well as small-scaled structures in synchrotron nebulae. In this brief review we discuss results from early Chandra studies of pulsars and SNRs.

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.

X-Ray Emission Associated with Filament Activity

1979 ◽  
Vol 44 ◽  
pp. 269-271 ◽  
Author(s):  
L.W. Acton ◽  
J.M. Mosher
Keyword(s):  
Spatial Resolution ◽  
Time Resolution ◽  
Active Regions ◽  
Spatial Relationships ◽  
Solar Plasma ◽  
X Ray ◽  
Small X ◽  
Temporal And Spatial

The purpose of this research is to investigate the temporal and spatial relationships of activated filaments, soft X-ray production, and Ha flares. The X-ray data are from the Lockheed Mapping X-Ray Heliometer (MXRH) on 0S0-8 (Wolfson et al., 1975, 1977). This instrument has been operating continuously since July 1975. It responds to radiation from solar plasma above about 2 × 106K, provides a time resolution of 20 sec, a spatial resolution of 2-3 arc min and has a basic sensitivity roughly equivalent to the 1-8 Å full disc monitors of, e.g., the SOLRAD and SMS/GOES satellites (threshold ≈ 2 × 10-9W/m2). However, because of its spatial resolution the MXRH permits study of small X-ray events in individual active regions even when the integrated solar X-ray emission is high.

scholarly journals Комплекс SOLPEX для исследования излучения Солнца в мягком рентгеновском диапазоне волн

2019 ◽  
Vol 89 (12) ◽  
pp. 1832
Author(s):  
С.В. Кузин ◽  
А.С. Кириченко ◽  
M. Steslicki ◽  
J. Sylwester ◽  
M. Siarkowski ◽  
...  
Keyword(s):  
Time Resolution ◽  
Angular Resolution ◽  
Focal Length ◽  
Space Station ◽  
Pinhole Camera ◽  
International Space ◽  
X Ray ◽  
Spectral Diagnostics ◽  
Input Filter ◽  
Fast Rotating

Abstract The SOLPEX complex consists of two instruments for recording soft X-ray radiation from the Sun and is a part of the KORTES equipment, which will be installed on board the International Space Station. The first instrument is a fast-rotating multi-crystalagg spectrometer designed to record solar spectra in the range of 0.4–23 Å with a time resolution of no less than 0.1 s. The second instrument is a pinhole camera with a focal length of 58 cm. The camera has a field of viewof 2° × 2°, angular resolution of 2 arcmin, and time resolution up to 0.2 s. The energy range is determined by the input filter and is 1–10 keV; the energy resolution is 0.5 keV. The combination of these two instruments makes it possible to locate hot solar sources in the corona, determine their speed, and conduct spectral diagnostics.

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.

Solvation dynamics monitored by combined X-ray spectroscopies and scattering: photoinduced spin transition in aqueous [Fe(bpy)3]2+

2014 ◽  
Vol 171 ◽  
pp. 169-178 ◽  
Author(s):  
C. Bressler ◽  
W. Gawelda ◽  
A. Galler ◽  
M. M. Nielsen ◽  
V. Sundström ◽  
...  
Keyword(s):  
Time Resolution ◽  
Time Scale ◽  
Spin Transition ◽  
Solvation Shell ◽  
Precise Determination ◽  
Heating Process ◽  
Solvation Dynamics ◽  
X Ray ◽  
Structure Changes

We have studied the photoinduced low spin (LS) to high spin (HS) conversion of aqueous Fe(bpy)3 with pulse-limited time resolution. In a combined setup permitting simultaneous X-ray diffuse scattering (XDS) and spectroscopic measurements at a MHz repetition rate we have unraveled the interplay between intramolecular dynamics and the intermolecular caging solvent response with 100 ps time resolution. On this time scale the ultrafast spin transition including intramolecular geometric structure changes as well as the concomitant bulk solvent heating process due to energy dissipation from the excited HS molecule are long completed. The heating is nevertheless observed to further increase due to the excess energy between HS and LS states released on a subnanosecond time scale. The analysis of the spectroscopic data allows precise determination of the excited population which efficiently reduces the number of free parameters in the XDS analysis, and both combined permit extraction of information about the structural dynamics of the first solvation shell.

Mass and Energy Flow in the Solar Atmosphere Implications of Skylab Observations

1977 ◽  
Vol 36 ◽  
pp. 263-315
Author(s):  
George L. Wlthbroe
Keyword(s):  
Solar Atmosphere ◽  
Energy Flow ◽  
Large Scale ◽  
Strong Field ◽  
Coronal Holes ◽  
Active Regions ◽  
Weak Field ◽  
X Ray ◽  
The North ◽  
East Limb

The Skylab experiments acquired a wealth of observations applicable to investigating problems associated with the mass and energy flow in the solar atmosphere. In this review we discuss some of the observations of quiet regions, coronal holes and active regions and Illustrate the fundamental role that magnetic fields play in defining the structure and the mass and energy flow in these regions. Figure 1 (Altschuler et al., 1976) illustrates three major classes of structure: (1) strong field, magnetically closed areas typified by active regions, (2) weak field, open regions which, according to present evidence, appear to be associated primarily with coronal holes, and (3) weak field regions which appear to be magnetically closed on a large scale and appear to be associated primarily with normal quiet areas. Some of these latter structures can be seen in the X-ray photograph presented in Figure 2 (Vaiana et al., 1973a). Also evident in this figure are large coronal holes near the east limb at the north pole.

scholarly journals Rapid X-Ray Variability of Cyg X-1

1998 ◽  
Vol 188 ◽  
pp. 382-383
Author(s):  
P. C. Agrawal ◽  
B. Paul ◽  
A. R. Rao ◽  
M. N. Vahia ◽  
J. S. Yadav ◽  
...  
Keyword(s):  
Black Hole ◽  
Time Scales ◽  
Time Resolution ◽  
Time Variability ◽  
X Ray ◽  
Black Hole Binary ◽  
Different Time Scales

We have made observations of the black hole binary Cyg X-1 with the Indian X-ray Astronomy Experiment (IXAE). Observations made with time resolution ranging from 0.4 ms to 1 s showed variations and flaring activity on sub-sec and longer time scales. Results on time variability on different time scales and flaring characteristics in the two states of Cyg X-1 are presented.

A Discussion on the physics of the solar atmosphere - The x-ray corona from Skylab

1976 ◽  
Vol 281 (1304) ◽  
pp. 365-374 ◽  
Keyword(s):  
Large Scale ◽  
Dense Plasma ◽  
Coronal Holes ◽  
Active Regions ◽  
Coronal Loops ◽  
Closed Loops ◽  
X Ray ◽  
Physical Conditions ◽  
Wide Range ◽  
The Magnetic Field

An overview of the images obtained with the A.S. & E. X-ray telescope on Skylab shows the low corona to be highly structured. The plasma is distributed in closed loops shaped by the magnetic field with sizes ranging from the smallest resolvable structures of a few thousand kilometres to loops that reach halfway across the solar disk. Relatively high-temperature and dense plasma loops overlay active regions; large-scale interconnections link active regions to their surrounding fields and in some cases to other active regions. The large-scale loops, which cover most of the Sun outside of active regions, appear to be related to old active regions whose magnetic fields have spread out over the course of several solar rotations. Often at the poles and occasionally on the disk, large regions display radial field configurations (coronal holes) from which the plasma preferentially escapes into high-velocity solar wind streams. A comprehensive view of the structure and evolution of the X-ray corona is given in terms of the physical conditions existing in the various coronal loops, and the importance of active regions is emphasized by examining their structure and time development over a wide range of scales.

scholarly journals Characteristics of Anemone Active Regions Appearing in Coronal Holes Observed with theYohkohSoft X‐Ray Telescope

2008 ◽  
Vol 673 (2) ◽  
pp. 1188-1193 ◽  
Author(s):  
Ayumi Asai ◽  
Kazunari Shibata ◽  
Hirohisa Hara ◽  
Nariaki V. Nitta
Keyword(s):  
Coronal Holes ◽  
Active Regions ◽  
X Ray
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