On Filter Observations of Coronal Structures in the Light of FeX 6374 Å Emission Line

AbstractThe red coronal line of Fe X (6374 Å) seems to be extremely suitable for filter observations due to reduced sky scattering in this spectral interval and absence of blending by Fraunhofer lines. Comparative analysis of location of Hαstructures in colour and black-white pictures of the solar corona of July 11, 1991 was carried out. A conclusion was made that care should be taken when interference filters are used for the red corona observations. Non-ideal monochromatization of present-day existing interference filters may be responsible for some ”false“ red and white coronal structures which belong to Hαprominence emission. Estimations of parameters of an interference filter for the reliable red coronal observations are presented.

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Analysis of non-thermal velocities in the solar corona

Annales Geophysicae ◽

10.5194/angeo-22-3055-2004 ◽

2004 ◽

Vol 22 (8) ◽

pp. 3055-3062 ◽

Cited By ~ 6

Author(s):

L. Contesse ◽

S. Koutchmy ◽

C. Viladrich

Keyword(s):

Solar Corona ◽

Emission Line ◽

Signal To Noise Ratio ◽

Central Line ◽

Line Of Sight ◽

Polar Regions ◽

Full Line ◽

Coronal Line ◽

Signal To Noise ◽

Line Widths

Abstract. We describe new ground-based spectroscopic observations made using a 40-cm aperture coronagraph over a whole range of radial distances (up to heights of 12' above the limb) and along four different heliocentric directions N, E, S and W. The analysis is limited to the study of the brightest forbidden emission line of Fe XIV at 530.3nm, in order to reach the best possible signal-to-noise ratio. To make the results statistically more significant, the extracted parameters are averaged over the whole length of the slit, and measurements are repeated fives times at each position; the corresponding dispersions in the results obtained along the slit are given. Central line profile intensities and full line widths (FWHM) are plotted and compared to measurements published by other authors closer to the limb. We found widths and turbulent (non-thermal) velocities of significantly higher values above the polar regions, especially when a coronal hole is present along the line of sight. We do not see a definitely decreasing behaviour of widths and turbulent velocities in equatorial directions for larger radial distances, as reported in the literature, although lower values are measured compared to the values in polar regions. The variation in the high corona is rather flat and a correlation diagram indicates that it is different for different regions and different radial distances. This seems to be the first analysis of the profiles of this coronal line, up to large heights above the limb for both equatorial and polar regions.

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Colour Photometry of the Solar Corona of July 11, 1991

International Astronomical Union Colloquium ◽

10.1017/s0252921100026129 ◽

1994 ◽

Vol 144 ◽

pp. 597-599 ◽

Cited By ~ 1

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.

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

International Astronomical Union Colloquium ◽

10.1017/s0252921100026038 ◽

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.

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

International Astronomical Union Colloquium ◽

10.1017/s0252921100026002 ◽

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.

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Solar Corona Investigation by the Coronal Line Photometer at Lomnický Peak

International Astronomical Union Colloquium ◽

10.1017/s0252921100025744 ◽

1994 ◽

Vol 144 ◽

pp. 431-434

Author(s):

M. Minarovjech ◽

M. Rybanský

Keyword(s):

Solar Corona ◽

Time Resolution ◽

Active Regions ◽

High Time ◽

High Time Resolution ◽

List Type ◽

Type Number ◽

Coronal Line ◽

Global Cycle

AbstractThis paper deals with a possibility to use the ground-based method of observation in order to solve basic problems connected with the solar corona research. Namely:1.heating of the solar corona2.course of the global cycle in the corona3.rotation of the solar corona and development of active regions.There is stressed a possibility of high-time resolution of the coronal line photometer at Lomnický Peak coronal station, and use of the latter to obtain crucial observations.

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White-Light Coronal Structures: Streamers and CMEs

International Astronomical Union Colloquium ◽

10.1017/s0252921100025045 ◽

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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Exploring Coronal Structures with SOHO

International Astronomical Union Colloquium ◽

10.1017/s0252921100064915 ◽

2000 ◽

Vol 179 ◽

pp. 403-406

Author(s):

M. Karovska ◽

B. Wood ◽

J. Chen ◽

J. Cook ◽

R. Howard

Keyword(s):

Solar Corona ◽

Image Enhancement ◽

Coronal Mass Ejections ◽

Dynamical Evolution ◽

Small Scale ◽

Low Contrast ◽

Contrast Structures ◽

Scale Structures ◽

Small Scale Structures ◽

Coronal Structures

AbstractWe applied advanced image enhancement techniques to explore in detail the characteristics of the small-scale structures and/or the low contrast structures in several Coronal Mass Ejections (CMEs) observed by SOHO. We highlight here the results from our studies of the morphology and dynamical evolution of CME structures in the solar corona using two instruments on board SOHO: LASCO and EIT.

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