The connection between X-ray and radio emission from active regions on the sun for an inhomogeneous model

1973 ◽  
Vol 16 (12) ◽  
pp. 1422-1426
Author(s):  
A. S. Grebinskii
Keyword(s):  
Radio Emission ◽  
Active Regions ◽  
The Sun ◽  
X Ray ◽  
Inhomogeneous Model

scholarly journals Solar activity and solar oscillations

1997 ◽  
Vol 181 ◽  
pp. 277-285
Author(s):  
Y. Elsworth
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Radio Emission ◽  
Surface Temperature ◽  
The Sun ◽  
Solar Oscillations ◽  
Thermal Component ◽  
X Ray ◽  
Convective Flows ◽  
Wide Range

Helioseismology provides us with the tools to probe solar activity. So that we can consider how the solar oscillations are influenced by that activity, we first consider the phenomena that we associate with the active Sun. The surface of the Sun is not quiet but shows evidence of convection on a wide range of scales from a few hundred kilometres through to several tens-of-thousands of kilometres. The surface temperature shows signs of the convection structures with the temperature in the bright granules being some 100 K to 200 K hotter than the surrounding dark lanes. Sunspots, which are regions of high magnetic field that suppress convective flows, are clearly visible to even quite crude observations. They are several tens-of-thousands of kilometres in diameter and about 2000 K cooler than their surroundings. Ultraviolet and X-ray pictures from satellites show that the higher layers of the solar atmosphere are very non-uniform with bright regions of high activity. Contemporaneous magnetograms show that these regions are associated with sunspots. Flares - regions of magnetic reconnections - are seen at all wavelengths from X-ray through the visible to radio. They are the non-thermal component of the radio emission of the Sun. There are many other indicators of activity on the Sun.

New observational data on x-ray flares and active regions on the sun

1985 ◽  
Vol 28 (3) ◽  
pp. 270-271
Author(s):  
I A Zhitnik ◽  
S L Mandel'shtam ◽  
I P Tindo ◽  
A M Urnov
Keyword(s):  
Observational Data ◽  
Active Regions ◽  
The Sun ◽  
X Ray

scholarly journals Recent High Resolution X-Ray Spectra of the Sun

1972 ◽  
Vol 14 ◽  
pp. 740-741
Author(s):  
J. H. Parkinson ◽  
K. Evans ◽  
K. A. Pounds
Keyword(s):  
High Resolution ◽  
Active Region ◽  
Wavelength Range ◽  
South Australia ◽  
Active Regions ◽  
Effective Area ◽  
Field Of View ◽  
The Sun ◽  
X Ray

New results are presented from high resolution Bragg crystal spectrometers flown in late 1970 on two Skylark rockets. The first instrument, launched on 24 November 1970 at 22 13 UT from Woomera, South Australia, contained two crystal spectrometers, each with an effective area of 50 cm2 and field collimation to 3’ FWHM. This instrument obtained the X-ray spectrum of the quiet corona in the wavelength range 5–14 Å. The second instrument was launched on 6 December 1970 at 11 13 UT from Sardinia, Italy, and contained four crystals of 6 cm2, each collimated to 4’ FWHM. This instrument was pointed at a non-flaring active region near N20 W40(McMath region 11060), and obtained an X-ray spectrum between 5 and 23 Å. This first use of a collimator to limit the field of view has considerably increased the spectral clarity compared with earlier observations by excluding the contributions of other active regions.

scholarly journals X-Ray Spectroscopy of Solar Active Regions During the Third Skylab Mission

1975 ◽  
Vol 68 ◽  
pp. 65-66
Author(s):  
J. P. Pye ◽  
R. J. Hutcheon ◽  
J. H. Parkinson ◽  
K. A. Pounds
Keyword(s):  
Wavelength Range ◽  
South Australia ◽  
Active Regions ◽  
Sounding Rocket ◽  
The Sun ◽  
X Ray ◽  
The Third ◽  
American Science ◽  
Solar Active Regions ◽  
Plane Scanning

SummaryThis paper describes the analysis of soft X-ray spectra of solar active regions observed on a Skylark sounding rocket flight. The experiment was launched from Woomera, South Australia, at 0535 UT on 26th November 1973. The payload consisted of 3 plane scanning Bragg crystal spectrometers, covering the wavelength range 4 to 23 Å, and collimated to 3 arc min FWHM. The instrument was the same as that used by Parkinson (1972, 1973). The launch was part of a collaborative observing program with American Science & Engineering who obtained X-ray photographs of the Sun with the S0-54 ATM X-ray telescope, simultaneously with the Leicester observations. We report preliminary results for McMath region 12624 (S10 W28). This region was observed about 60 min after the peak of an importance – N, class CO flare.

New observational data on x-ray flares and active regions on the sun

1985 ◽  
Vol 145 (3) ◽  
pp. 530
Author(s):  
I.A. Zhitnik ◽  
S.L. Mandel'shtam ◽  
I.P. Tindo ◽  
A.M. Urnov
Keyword(s):  
Observational Data ◽  
Active Regions ◽  
The Sun ◽  
X Ray

scholarly journals Two Kinds of Activity in Late-type Stars

1991 ◽  
Vol 130 ◽  
pp. 440-442
Author(s):  
M.M. Katsova
Keyword(s):  
Magnetic Field ◽  
Active Regions ◽  
Field Measurements ◽  
Spherically Symmetric ◽  
The Sun ◽  
Late Type ◽  
X Ray ◽  
Magnetic Field Measurements ◽  
Local Magnetic Fields ◽  
Uniform Manner

Several years ago we proposed a method for the analysis of X-ray observations of late-type stars. It allowed the determination in a uniform manner of coronal base electron densities for more than 40 late-type stars, in terms of a one-temperature consideration of homogeneous spherically symmetric coronae (Katsova et al., 1987). Fig. 1 shows the results as a function of spectral type. Comparison of our results with values for different kinds of solar regions shows that physical characteristics of F and G star coronae correspond to densities less than those in active regions on the Sun. Values for the active K-M0 stars are comparable with those of dense steady condensations found directly above large sunspots.On this basis, activity can be explained as an increase in that part of the stellar surface that is occupied by strong local magnetic fields. This is illustrated in the table where we compare magnetic field measurements by Saar and Linsky (1988) with our calculations.

Crystal spectrometry of active regions on the Sun

1973 ◽  
Vol 334 (1597) ◽  
pp. 231-239 ◽  
Keyword(s):  
Line Emission ◽  
Active Regions ◽  
Field Of View ◽  
Sounding Rocket ◽  
The Sun ◽  
Crystal Spectrometer ◽  
Isothermal Model ◽  
X Ray ◽  
Solar Observations ◽  
History Of

A crystal spectrometer has been flown on a sounding rocket to study the soft X-ray line emission from the sun. Collimators, with a field of view 9 arc min square, allowed individual active regions to be observed. A detailed description of the instrument is given. Solar conditions at the time of launch are then discussed, together with a brief history of the three active regions studied. It is shown that the collimators performed satisfactorily. The spectrum of an active region is used to identify the important solar line emission, and a comparison of the spectra obtained near 1.7 nm is made. The temperatures of the regions are discussed, and it is shown that a non-isothermal model is required. A good correlation is found between the soft X-ray emission and other solar observations.

scholarly journals Solar Arcade Flarings as Magnetodynamic Process of Mass and Energy Shedding from Energized Magnetic Regions

1998 ◽  
Vol 188 ◽  
pp. 21-24
Author(s):  
Y. Uchida ◽  
S. Hirose ◽  
S. Cable ◽  
S. Uemura ◽  
K. Fujisaki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Alternative Model ◽  
Classical Model ◽  
Active Regions ◽  
The Sun ◽  
High Latitudes ◽  
X Ray ◽  
Spatially Resolved ◽  
Astrophysical Objects

Prototypes of magnetic actions in producing and shedding the X-ray-emitting high temperature plasmas in various astrophysical objects are witnessed in the spatially-resolved form on the Sun by the Solar X-ray Satellite “Yohkoh”. The most prominent of those are arcade flarings seen as powerful arcade flares in active regions with strong magnetic field. Larger scale fainter X-ray arcade formation observed at high latitudes, shedding a large amount of mass and energy as CME's (coronal mass ejections) also belongs to this category. Since some features found by the new observation by Yohkoh are incompatible with the so-called “classical model of arcade flarings”, we advance an alternative model based on the quadruple magnetic sources in the photosphere.

scholarly journals The solar corona above active regions: a comparison of extreme ultraviolet line emission with radio emission

1968 ◽  
Vol 35 ◽  
pp. 404-410 ◽  
Author(s):  
Werner M. Neupert
Keyword(s):  
Active Region ◽  
Radio Emission ◽  
Solar Corona ◽  
Extreme Ultraviolet ◽  
Line Emission ◽  
Active Regions ◽  
Emission Lines ◽  
Line Radiation ◽  
X Ray ◽  
Spot Group

The observations of extreme ultraviolet (EUV) emission lines of Feix through Fe XVI made by OSO-I have been applied to a study of the solar corona above active regions. Ultraviolet and radio emission are determined for several levels of activity classified according to the type of sunspot group associated with the active region. Both radio emission and line radiation from Fe XVI, the highest stage of ionization of Fe observed, are observed to increase rapidly with the onset of activity and are most intense over an E spot group early in the lifetime of the active region. As activity diminishes, radiation from Fe XV and Fe XIV becomes relatively more prominent. Preliminary X-ray data from OSO-III obtained during a flare are introduced. These indicate that radiation from the highest stage of iron thus far observed, Fe XXV, reaches a maximum first in an X-ray burst and that maxima in lower stages of ionization follow, with delays from 2 to 15 min.

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