On the Optical Polarization of the White-Light Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 601-604
Author(s):  
B. P. Filippov ◽  
M. M. Molodensky ◽  
S. Koutchmy
Keyword(s):  
Solar Corona ◽  
White Light ◽  
Scattering Theory ◽  
Radial Direction ◽  
Polarization Plane ◽  
Solar Limb ◽  
Thomson Scattering ◽  
Optical Polarization ◽  
Special Experiment ◽  
Coronal Structures

AbstractA special experiment was designed to measure the orientation of the polarization plane in the solar corona during the total eclipse of July 11, 1991. Rotating polaroids with the axes directed at +45° and at −45° of the radial direction in all directions were used. The polarization plane was found to be tangential to the solar limb everywhere with an accuracy within 1°, in agreement with the Thomson scattering theory.

scholarly journals Density Irregularity of the Inner Corona determined from Simultaneous Measurements of the XUV and the K Coronal Brightness

1990 ◽  
Vol 142 ◽  
pp. 253-254
Author(s):  
M. Guhathakurta ◽  
G.J. Rottmann ◽  
R.R. Fisher ◽  
F.Q. Orrall
Keyword(s):  
Electron Density ◽  
White Light ◽  
Light Emission ◽  
Solar Limb ◽  
Position Angle ◽  
Thomson Scattering ◽  
White Light Emission ◽  
Kinetic Temperature ◽  
Data Sets ◽  
Chemical Abundance

In this paper we report preliminary results from a study of the inner corona based on the direct comparison of XUV resonance emission line λ174.53 FeX with that of the white-light emission from the K corona. The data sets were obtained 17718th of March, 1988, during a total solar eclipse of the sun and consists of co-spatial and co-temporal measurements of these two quantities as a function of position angle and height above the solar limb. The local emission of a coronal resonance line is proportional to the electron density squared, the chemical abundance, and the electron kinetic temperature, while the white-light emission (arising from Thomson scattering by electrons) depends directly on the electron density and the local radiation field. Taken together these measurements yield an estimate of the quantity where n is the electron density. This quantity, called “X the coronal irregularity factor” by C.W. Allen, is found to be >1.

scholarly journals The Large-Scale Structure of the Corona

1980 ◽  
Vol 5 ◽  
pp. 549-556
Author(s):  
Jack B. Zirker
Keyword(s):  
Solar Corona ◽  
White Light ◽  
Large Scale ◽  
Dimensional Space ◽  
Coronal Holes ◽  
Solar Limb ◽  
Active Regions ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Fast Wind

The solar corona serves as a prototype of the outer atmospheres of all cool stars. Because of its nearness we can study this prototype in more detail than any other example. Considerable progress has been made recently in understanding how the large scale structure of the solar corona controls the genesis of the solar wind and the distribution of slow and fast wind streams throughout the three-dimensional space surrounding the sun. In this review we will discuss some of the progress made in this field during the last few years. We will emphasize the observational data and the inferences that can be made more or less directly from them. T. Holzer will discuss the theoretical aspects of stellar wind acceleration in another paper in this symposium.The large scale structures of the solar corona consist essentially of three kinds: streamers, active regions and coronal holes. Figure 1 is a familiar photograph of the solar corona, obtained in white light at the total eclipse of 30 June 1973 by the High Altitude Observatory. The streamers are the petal-like structures extending out from the black lunar limb. They taper to narrow radial spikes that have been traced out as far as 10-12 solar radii (Keller, 1979). Daily measurements of the white light corona at the Mauna Loa Observatory (Hundhausen et al. 1979) and the Pic-du-Midi Observatory (Dollfus et al., 1977) since 1965 show that the streamers are fan-shaped structures that may extend 120° in solar longitude. We see them in various perspectives at the solar limb.

scholarly journals Polarization of white-light solar corona and sky polarization effect during total solar eclipse on March 29, 2006

2019 ◽  
pp. 83-87 ◽  
Author(s):  
V. Merzlyakov ◽  
Ts. Tsvetkov ◽  
L. Starkova ◽  
R. Miteva
Keyword(s):  
Solar Corona ◽  
Solar Eclipse ◽  
White Light ◽  
Linear Dependence ◽  
Polarization Effect ◽  
Thomson Scattering ◽  
Total Solar Eclipse ◽  
Degree Of Polarization ◽  
The Sun ◽  
Eclipse Observations

Ground-based total solar eclipse observations are still the key method for coronal investigations. The question about its white-light degree of polarization remains unanswered. There are hypotheses claiming that the degree of polarization in certain regions of the corona may be higher than the maximal theoretically predicted value determined by Thomson scattering. We present polarization of the white-light solar corona observations obtained by three different teams during the March 29, 2006 solar total eclipse. We give an interpretation on how the polarization of the sky impacts brightness of the polarized solar corona, depending on the landscape during the totality. Moreover, it is shown that the singular polarization points of the corona are in linear dependence with the height of the Sun above the horizon.

The Corona Electropolarimetry during July 11, 1991 Solar Eclipse

1994 ◽  
Vol 144 ◽  
pp. 529-533 ◽  
Author(s):  
V. Kulidzanishvili ◽  
A. Mayer ◽  
V. Mayer ◽  
S. Danik
Keyword(s):  
Solar Corona ◽  
Solar Eclipse ◽  
Radial Direction ◽  
Polarization Plane ◽  
Polarization Degree ◽  
Plane Direction ◽  
Coronal Streamers ◽  
Academy Of Sciences

AbstractThe electropolarimetry of July 11, 1991 eclipse solar corona using the new photoelectric polarimeter of Abastumani Astrophysical Observatory of the Georgian Academy of Sciences, equipped with the IBM computer, is described in this paper.By means of measurable values the isopolarization lines were constructed, which turned out to be stretched along the coronal streamers. The polarization plane has, entirely, radial direction; however, small but real deviations from radiality were established. The errors of measurements of intensity, polarization degree and polarization plane direction are evaluated.

Colour Photometry of the Solar Corona of July 11, 1991

1994 ◽  
Vol 144 ◽  
pp. 597-599 ◽  
Author(s):  
I. V. Alexeyeva ◽  
N. L. Kroussanova ◽  
M. V. Streltsova
Keyword(s):  
Solar Corona ◽  
Red Emission ◽  
Coronal Structures

AbstractThe results of photometry of colour positives of the solar corona of July 11, 1991 are presented. Observations of the white corona were made without radial niters in Jojutla (Mexico). Dependences of coronal brightness on distance in the red (640 nm) and blue (420 nm) wavelength intervals are deduced for different coronal structures up to 3.0-3.5R⊙. The effect of ”reddening“ is noted. The excess of the red emission to the blue one (I640nm/I420nm) is found to be 1.20 and 1.17 at distance of 2.2R⊙for the N-E helmet streamer (P ≃ 37°) and the N-W region of low brightness (P ≃ 339°), respectively.

July 11, 1991 Eclipse Corona Photometry by the Results of Electropolarimetric and CCD-Matrix Observations

1994 ◽  
Vol 144 ◽  
pp. 567-569
Author(s):  
V. Kulidzanishvili ◽  
D. Georgobiani
Keyword(s):  
Solar Corona ◽  
Observational Data ◽  
Solar Limb ◽  
Ccd Matrix

AbstractThe observational data of July 11, 1991 eclipse solar corona obtained by both electropolarimeter (EP) and CCD-matrix were processed. Using these data, the solar corona photometry was carried out. The results of EP data are compared with the ones of CCD data. It must be noted here that the CCD data give us only characteristics of the inner corona, while the EP data show the features of both the inner and middle corona up to 4R⊙. Standard flattening indexϵis evaluated from both data. The dependence of the flattening index on the distance from the solar limb is investigated. The isophotes in Na and Ca lines are plotted. Based on these data some ideas and conclusions on the type of the solar corona are presented.

Calculated Coronal Magnetic Fields and Their Comparison with the Coronal Structures as Observed during Five Solar Eclipses

1994 ◽  
Vol 144 ◽  
pp. 559-564
Author(s):  
P. Ambrož ◽  
J. Sýkora
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Coronal Magnetic Field ◽  
Coronal Magnetic Fields ◽  
Solar Eclipses ◽  
Coronal Structures

AbstractWe were successful in observing the solar corona during five solar eclipses (1973-1991). For the eclipse days the coronal magnetic field was calculated by extrapolation from the photosphere. Comparison of the observed and calculated coronal structures is carried out and some peculiarities of this comparison, related to the different phases of the solar cycle, are presented.

FeXIV Line Emission Polarization of the July 11, 1991 Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 541-547
Author(s):  
J. Sýkora ◽  
J. Rybák ◽  
P. Ambrož
Keyword(s):  
High Resolution ◽  
Solar Corona ◽  
Emission Line ◽  
Solar Eclipse ◽  
White Light ◽  
Preliminary Analysis ◽  
Line Emission ◽  
Total Solar Eclipse ◽  
Degree Of Polarization ◽  
High Resolution Images

AbstractHigh resolution images, obtained during July 11, 1991 total solar eclipse, allowed us to estimate the degree of solar corona polarization in the light of FeXIV 530.3 nm emission line and in the white light, as well. Very preliminary analysis reveals remarkable differences in the degree of polarization for both sets of data, particularly as for level of polarization and its distribution around the Sun’s limb.

Synoptic Charts of the Solar Eclipses of 1990 and 1991

1994 ◽  
Vol 144 ◽  
pp. 517-521
Author(s):  
Z. Mouradian ◽  
G. Buchholtz ◽  
G. Zlicaric
Keyword(s):  
Solar Limb ◽  
Active Regions ◽  
Solar Eclipses ◽  
Coronal Structures

AbstractThe synoptic charts of solar rotations 1831 and 1844 have been drawn up, corresponding to the eclipses of 22 July 1990 and 11 July 1991. These charts contain the active regions and the filaments, and show the position of the solar limb, at the time of the eclipse. They are for use in studying the coronal structures observed during these eclipses. The variation of these structures is given in the table. The last section of the article contains a formula for identifying the structures out of the limb.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

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