Issue 18

Ehangiad ardaloedd bywiog o’r Haul i’r gofod (The expansion of solar active regions into space)

The Sun’s complex magnetic field permeates through the photosphere (the Sun’s surface) and into the corona (the Sun’s atmosphere). New magnetic fluxes arise from the photosphere in the form of closed loops which expand into the corona. This is a typical process of coronal active regions which creates and replenishes the coronal field. Magnetic field and plasma (energetic ionised gas) are transported through the corona and flow with the solar wind into the heliosphere (the region of space influenced by the Sun including the solar system). Transportation of this kind is seen during explosive events from the Sun. According to current thinking, the only transport of material from the closed field of active regions is through eruptive events, so in the absence of eruptions the active region plasma is isolated from the solar wind. This article presents evidence to the contrary. The observations show the first evidence of the direct, quiescent expansion of active region closed field into the extended corona without an eruption, thus forming an important part of the solar wind. The evidence is gained through the application of new image processing techniques to coronagraph observations. The observations are presented, and their implications are discussed in the context of the current model of Sun-heliospheric connections.


Sun, photosphere, corona, magnetic field, magnetic debris.


Morgan, H. (2014), 'Ehangiad ardaloedd bywiog o’r Haul i’r gofod', Gwerddon, 18, 10-22. 

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