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Solar eclipse
About: Solar eclipse is a research topic. Over the lifetime, 2737 publications have been published within this topic receiving 22625 citations.
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TL;DR: In this paper, the H-Balmer line densities from H8 to H31 at 4 wave lengths in the Balmer continuum were measured at 2 points on the limb on 17 spectrograms at second contact.
Abstract: : The analysis of UV spectrograms of the chromospheric flash was hindered since the UV standardizing exposures were unsatisfactory as a result of a failure of the film-advance mechanism. Characteristic curves from standard lamp exposures were useful principally as first approximations to the curves representing eclipse spectrograms. In addition, exposure-duration uncertainties existed on all except 6 spectrograms. However, methods were developed which allowed reliable determinations of the characteristic curves of the eclipse films; a satisfactory independent check was made of the consistency and accuracy of the final curves. The H-Balmer-line densities from H8 to H31 at 4 wave lengths in the Balmer continuum were measured at 2 points on the limb on 17 spectrograms at second contact. Tables are included of 24 corrected line intensities of the Balmer series at 108-km height separations in the lower chromosphere over the range from 100 to 3800 km. The Balmer decrements agreed well with those of the 1932 eclipse at chromosphere heights where observations overlap. The emission-height gradients of H are about 40% larger than in 1932, and the absolute intensities of the H emission at the chromosphere base are about 5 times as large as those in 1932. Preliminary results indicated pronounced self-absorption effects and large departures from thermodynamic equilibrium at 700 km and greater heights. Electron temperature was less than 12,000 k below 1000 km and increased at greater heights. Electron densities in the low chromosphere were of the order of 10 to the eleventh power/cc.
12 citations
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TL;DR: The solar corona is an extremely hot (106 K or about 0.1 keV), almost fully ionised plasma which extends from a few thousand km above the Sun's visible surface or photosphere (6000 K) to where it freely expands into the solar system as the solar wind as mentioned in this paper.
Abstract: The solar corona is an extremely hot (106 K or about 0.1 keV), almost fully ionised plasma which extends from a few thousand km above the Sun’s visible surface or photosphere (6000 K) to where it freely expands into the solar system as the solar wind. The exact reasons for its high temperature are still being debated despite more than 50 years of research, but magnetic fields are believed to be responsible for this heating. This article reviews some recent progress in our understanding, using data from spacecraft (Yohkoh, SOHO and TRACE) and from ground-based eclipse observations.
12 citations
01 Jan 2007
TL;DR: In this paper, the authors used a three-dimensional MHD model to predict the s tructure of the corona prior to the total solar eclipse of March 29, 2006, using the observed photospheric radial magnetic fields as a boundary condition.
Abstract: We describe the use of a three-dimensional MHD model to predict the s tructure of the corona prior to the total solar eclipse of March 29, 2006. The calculation uses the observed photospheric radial magnetic f ield as a boundary condition. We use a new version of our model that has an improved description of energy transport in the corona. The mo del allows us to predict the emission of X-ray and EUV radiation in t he corona. We compare the predicted polarization brightness in the co rona with four observations of the eclipse from Greece, Egypt, and Li bya, and we demonstrate that the model accurately predicts the largescale structure of the corona. We also compare X-ray emission from the model with GOES/SXI images.
12 citations
TL;DR: In this article, the geospace response to the partial solar eclipse (SE) of January 4, 2011 (magnitude 0.78) above Kharkiv is described.
Abstract: Incoherent scatter radar observation results of the geospace response to the partial solar eclipse (SE) of January 4, 2011 (magnitude 0.78) above Kharkiv are described. The response to the SE was observed in variations in the electron concentration, electron and ion temperatures, and the vertical component of the plasma motion velocity in a wide altitude range (190–420 km). Parameters of thermal and dynamic processes in the ionosphere are theoretically calculated for the SE. It is shown that the SE resulted in significant changes in the dynamic and thermal conditions in geospace. The results show good agreement with results of an analysis of the geospace plasma responses to SEs occurring above Kharkiv in 1999–2008.
12 citations
TL;DR: In this article, the effect of solar eclipses on geomagnetism has been examined using observations of the magnetic declination, compiled from eleven observatories near the path of totality of the solar eclipse of 30 June 1954, have been examined.
12 citations