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Evidence linking coronal transients to the evolution of coronal holes
Solar Physics, 1978The positions of X-ray coronal transients outside of active regions observed during Skylab were superposed on H-alpha synoptic charts and coronal hole boundaries for seven solar rotations. A detailed spatial association between the transients and neutral lines was confirmed.
David F. Webb +3 more
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Is the chromosphere hotter in coronal holes?
AIP Conference Proceedings, 1999Coronal holes are brighter than the quiet Sun in microwaves. Microwave emission from the quiet Sun is optically thick thermal bremsstrahlung from the upper chromosphere. Therefore, the optically thick layer in the coronal hole chromosphere must be hotter than the corresponding layer in the quiet chromosphere.
N. Gopalswamy +4 more
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2019
The term coronal hole has at least three definitions: (i) the darkest patches on the solar surface as measured in UV and soft x-rays; (ii) the lowest intensity regions measured above the limb, seen either during a total solar eclipse or with an occulting coronagraph; and (iii) open-field (or open-flux) regions, which are equivalent to the footpoints of
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The term coronal hole has at least three definitions: (i) the darkest patches on the solar surface as measured in UV and soft x-rays; (ii) the lowest intensity regions measured above the limb, seen either during a total solar eclipse or with an occulting coronagraph; and (iii) open-field (or open-flux) regions, which are equivalent to the footpoints of
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The Magnetic Nature of Coronal Holes
Science, 1996Solar wind streams originate from low-density, magnetically open regions of the sun's corona, known as coronal holes. The locations, areal sizes, rotation, and solar-cycle evolution of these regions can be reproduced and understood by applying simple extrapolation models to measurements of the photospheric magnetic field.
Yi-Ming Wang +2 more
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Differential rotation of coronal holes
Solar Physics, 1985Using KPNO helium 10830 A synoptic charts of Carrington rotations 1716 through 1739, and by assembling a time sequence representing single latitude zone, rotational properties of coronal holes for five zones of latitudes (±10°, ±20° – ±40°, and ±40° – ±60°) have been examined. It seems that the rotation period of coronal holes is a function of latitude,
Rajendra N. Shelke, M. C. Pande
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Statistical Studies of Coronal Mass Ejections and Coronal Holes
Geomagnetism and Aeronomy, 2017Statistical studies of coronal mass ejections (CMEs) and coronal holes (CHs) are reviewed. The work summarizes the historical and current results of statistical studies of CMEs and CHs and their parameters that have been obtained by various authors who considered these phenomena as independent manifestations of solar activity, as well as their mutual ...
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On the Electron density in a coronal hole
Solar Physics, 1995Electron density in a coronal hole is rediscussed using the new calculation for the Mgviii λ436.62/λ430.47 density-sensitive theoretical line ratio and with the help of available observations.
B. N. Dwivedi, Anita Mohan
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On the Visibility of Coronal Holes in Microwaves
Central European astrophysical bulletin, 2007Previous observations indicate that coronal holes generally appear as low brightness temperature regions in microwaves. However, within their borders local enhancements of radiation often occur. This is confirmed by comparing a full-disc solar image obtained at 37 GHz on 27 May 1993 with full-disc solar images obtained at various wavelengths. Microwave
Brajša, Roman +2 more
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Energetics of Solar Coronal Holes
1991We examine the energetics of a solar coronal hole in the framework of magnetohydrodynamics (MHD). Given typical values of the observed parameters, it is estimated that the Poynting flux maintained by the solar rotation and a trailing magnetic field is potentially capable of driving and heating a wind stream in a coronal hole region.
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