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.

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 The Sun-Spectroscopic Observations of the Coronal Emission Lines and ADITYA-1 Mission

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Jagdev Singh
Keyword(s):  
High Resolution ◽  
Solar Corona ◽  
Large Body ◽  
Solar Limb ◽  
Emission Lines ◽  
Coronal Loops ◽  
The Sun ◽  
Coronal Emission ◽  
Spectroscopic Observations ◽  
Line Widths

The sun and the solar atmosphere, known as solar corona have been studied in detail for centuries but still lot need to be understood about the sun. In the late 19th and earlier 20th century, the information gathered about the solar corona was from the brief moments available during the total solar eclipses. In the later part space observations provided a large body of information about the solar corona. We obtained systematic high resolution spectroscopic observations in [Fe x] 637.4 [Fe xi] 789.2, [Fe xiii] 1074.7, and [Fe xiv] 530.3 nm emission lines during the period of 1997-2007 with the 25-cm coronagraph at Norikura, Japan. The variation in line widths with height above the solar limb implies that one pair of lines indicate that top of coronal loops are hotter where as other pair of lines shows that loop top is cooler. To explain these results, we proposed an empirical model as all these results are difficult to explain using the existing models. With this background we planned and designed a visible emission line coronagraph (VELC). This instrument is in advance stage of fabrication and is expected to be launched in 2019-20. The challenges and required technical development for this mission are discussed.

Possible Errors in Coronagraphic Observations which Could Introduce Asymmetric Emissions from Antidiammetric Points of the Solar Limb

1994 ◽  
Vol 144 ◽  
pp. 131-134 ◽  
Author(s):  
J. C. Noëns ◽  
V. P. Tritakis ◽  
A. G. Paliatsos
Keyword(s):  
Solar Corona ◽  
Physical Phenomenon ◽  
Solar Limb ◽  
Random Errors ◽  
Optical Emissions ◽  
Systematic And Random Errors

AbstractAll the possible systematic and random errors which could introduce differential brightness of the optical emissions between the eastern and the western part of the solar corona, have been discussed. Since the above mentioned inequality has been already detected in all the optical emissions of the corona but no error which could introduce it has been determined, additional studies are necessary in both directions. First, to support that this inequality is consistent to a real physical phenomenon and second, that another error far from the already known is responsible for this particular effect.

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.

A Magnetofrictional model for the solar corona

2018 ◽  
Vol 13 (S340) ◽  
pp. 87-88
Author(s):  
Soumyaranjan Dash ◽  
Dibyendu Nandy
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Solar Corona ◽  
Observational Data ◽  
Space Weather ◽  
Coronal Magnetic Field ◽  
Weather Variations ◽  
The Magnetic Field

AbstractRegular reconstruction of global solar corona constrained by observational data is required to monitor the space weather variations. We develop a model for simulating the global coronal magnetic field using magnetofrictional approach. Here we perform simulations to study the evolution of the magnetic field associated with a bipolar active region in response to photospheric flows.

scholarly journals Summary of Session A: Coronal Heating and Solar Wind Acceleration

1998 ◽  
Vol 11 (2) ◽  
pp. 869-872
Author(s):  
Takashi Sakurai
Keyword(s):  
Solar Wind ◽  
Solar Corona ◽  
Solar Limb ◽  
Coronal Heating ◽  
High Mountains ◽  
Solar Wind Acceleration

The solar corona is not easily observable from the ground; only with the coronagraphs located in high mountains or at infrequent and short occasions of total eclipses. And in any case these observations are limited to the corona beyond the solar limb. Therefore, it is natural that our understanding of the physics of the solar corona has advanced dramatically by sustained observations from space-based platforms, like Skylab in the 1970’s. These several years are particularly notable in this respect, because of a wide variety of data from Yohkoh, Ulysses, and SOHO.

scholarly journals Looking for the FIP Effect in EUV Spectra

2001 ◽  
Vol 203 ◽  
pp. 356-358
Author(s):  
B. N. Dwivedi ◽  
E. Landi ◽  
A. Mohan
Keyword(s):  
Active Region ◽  
Solar Corona ◽  
Extreme Ultraviolet ◽  
Solar Limb ◽  
Magnetic Loop ◽  
Field Of View ◽  
Element Abundances ◽  
Line Intensities ◽  
Height Dependence ◽  
Considerable Detail

We present results from a study of extreme-ultraviolet (EUV) off-limb spectra obtained with the SUMER instrument on the spacecraft SOHO. Using EUV line intensities, we deduce plasma temperatures and densities in the off-limb solar plasma. We make use of this information to study the FIP effect in the solar corona. We have looked for FIP effect in EUV spectra obtained by SUMER in a considerable detail. In particular, we report K/Ar, Si/Ar and S/Ar relative element abundances and investigate the height dependence of the FIP bias in the solar corona. Also, we study the relative Mg/Ne abundance in an active region at the solar limb to investigate the correlation of the FIP bias with magnetic loop structures in the field of view.

scholarly journals The Sun-Spectroscopic Observations of the Coronal Emission Lines and ADITYA-1 Mission

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Jagdev Singh
Keyword(s):  
High Resolution ◽  
Solar Corona ◽  
Large Body ◽  
Solar Limb ◽  
Emission Lines ◽  
Coronal Loops ◽  
The Sun ◽  
Coronal Emission ◽  
Spectroscopic Observations ◽  
Line Widths

The sun and the solar atmosphere, known as solar corona have been studied in detail for centuries but still lot need to be understood about the sun. In the late 19th and earlier 20th century, the information gathered about the solar corona was from the brief moments available during the total solar eclipses. In the later part space observations provided a large body of information about the solar corona. We obtained systematic high resolution spectroscopic observations in [Fe x] 637.4 [Fe xi] 789.2, [Fe xiii] 1074.7, and [Fe xiv] 530.3 nm emission lines during the period of 1997-2007 with the 25-cm coronagraph at Norikura, Japan. The variation in line widths with height above the solar limb implies that one pair of lines indicate that top of coronal loops are hotter where as other pair of lines shows that loop top is cooler. To explain these results, we proposed an empirical model as all these results are difficult to explain using the existing models. With this background we planned and designed a visible emission line coronagraph (VELC). This instrument is in advance stage of fabrication and is expected to be launched in 2019-20. The challenges and required technical development for this mission are discussed.

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