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.
The expansion of solar active regions into space
Documents and links:
Feedback
Don't see what you want? Problem with the files? Do you have a suggestion? Send your feedback to us.
Related Resources
The psychological foundations of reading fluency: a review
Forty years of research into reading has elucidated many of the psychological processes underpinning the reading process, but until recently, the cognitive underpinnings of fluency have been relatively unknown. In this review, a description is provided of reading fluency as a cognitive and neurobiological phenomenon, including the research that has gone into understanding this process. My own and my colleagues’ work has focused heavily on this area, and I outline our main findings to date. I end by outlining the implications of this work for our understanding of reading fluency in normally developed and dyslexic adults.
The legacy of coal mining in the south Wales coalfield: water contamination and remedial options
Historic coal mining and the associated processes have had a detrimental effect on the natural environment in the south Wales coalfield as contaminated mine drainage from abandoned mines discharges into the local hydrological system. The legacy of coal mining includes the discharge of contaminated mine drainage from several abandoned mines and the formation of insoluble iron minerals. This article discusses the underground processes that lead to the formation of contaminated water and iron minerals. Four abandoned coal mines located in the western part of the coal field and the remediation systems operational at these sites were investigated. Contaminated mine waters at these sites are being remediated through the removal of iron so that the final concentrations are in line with those recommended by the Water Framework Directive.
A multiwavelength model to visualise and analyse magnetic fields in the solar corona
The Sun is a dynamic, complex system, full of interesting and important features. These kinds of features can be modeled in various ways, such as with Non-Linear Force-Free Field (NLFFF) models. In this paper, NLFFF simulations are built. The intention is to estimate spatial patterns of the magnetic field in the solar chromosphere and corona and changes in the free energy in the system, in particular losses of energy as a result of solar eruptions. Most existing models have a temporal cadence of 12 minutes at best (that is, the situation is simulated every 12 minutes). The method discussed in this paper makes various approximations but it aims to achieve a temporal cadence of 45 seconds. The method used is found to successfully simulate synthetic data, and when dealing with real data, it produces images which frequently correspond well to observations. Several reductions in the free energy of the system are seen, corresponding to observed eruptions.