coronal holes


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coronal holes

Regions of exceptionally low density and temperature compared with the surrounding solar or stellar corona. They overlie areas of the Sun's disk that are characterized by relatively weak divergent (and therefore primarily unipolar) magnetic fields, and are thought to be the primary source of the high-speed streams of energetic charged particles in the solar wind.
References in periodicals archive ?
Due to the rotation of the Sun, one of its coronal holes has been oriented toward the direction of Earth.
The bottom-left X-ray image was taken on 7 April 2009, at activity minimum, and shows equatorial and polar coronal holes.
[35] used the full-disk He ii 304 [Angstrom] movies from the Atmospheric Imaging Assembly on SDO to study the cool (T ~ [10.sup.5] K) component of X-ray jets observed in polar coronal holes by XRT.
However, at coronal holes, the magnetic field lines don't close back on themselves and blow straight out into space.
The presence of 'anchoring' within coronal holes and the rigid rotation of the corona is best explained by condensed matter.
Coronal holes are a typical feature on the sun, though they appear at different places and with more frequency at different times of the sun's activity cycle.
It is clearly shown here that the fast wind at high latitudes is closely associated with polar coronal holes where the magnetic field is open, and also that the slow wind at the equator is mostly linked to either the boundary region of polar coronal holes or the isolated low-latitude coronal holes.
Coronal holes are cooler than other parts of the Sun, and magnetic waves appear to deposit more energy in the cooler regions than in the atmosphere's warmer parts.
In contrast to recent minima, it displayed low sunspot numbers, a delayed new-cycle activity, weak polar magnetic fields, and smaller polar coronal holes with less open flux.
SXI also will monitor coronal holes -- persistent sources of high-speed solar wind.
Learn about solar wind, solar flares, and coronal holes, and practice space weather-forecasting skills.