Coronal hole

  • Coronal Hole
  • An extended region of the corona, exceptionally low in density and associated with unipolar photospheric regions. A coronal hole can be an "open" magnetic field in the corona and (perhaps) inner heliosphere which has a faster than average outflow (wind); A region of lower than "quiet" ion and electron density in the corona; or a region of lower peak electron temperature in the corona than in the "quiet" corona.
Abstract from DBPedia
    A coronal hole is a temporary region of relatively cool, less dense plasma in the solar corona where the Sun's magnetic field extends into interplanetary space as an open field. Compared to the corona's usual closed magnetic field that arches between regions of opposite magnetic polarity, the open magnetic field of a coronal hole allows solar wind to escape into space at a much quicker rate. This results in decreased temperature and density of the plasma at the site of a coronal hole as well as an increased speed in the average solar wind measured in interplanetary space.

    コロナホール(Coronal hole)は、太陽のコロナが平均よりも暗く、冷たく、密度が低い領域である。コロナの構造の解明のために地球の大気外に打ち上げられたスカイラブ計画のX線望遠鏡によって発見された。コロナホールは、開いた磁力線が密集した単極に繋がっている。太陽活動の極小期には、コロナホールは主に極地方で見られるが、極大期にはどこにでも存在しうる。太陽風の速い成分は、開いた磁力線に沿って移動し、コロナホールを通ることが知られている。