Solar Flares: Solar Sigmoids Explained

ScienceDaily ^ | Apr. 27, 2009

[Ernest_at_the_Beach]

'Sigmoids' are S-shaped structures found in the outer atmosphere of the Sun (the corona), seen with X-ray telescopes and thought to be a crucial part of explosive events like solar flares. Now a group of astronomers have developed the first model to reproduce and explain the nature of the different stages of a sigmoid’s life.

Professor Alan Hood and Dr. Vasilis Archontis, both from the Mathematical Institute at St. Andrews University, Scotland, will present the team’s results at the European Week of Astronomy and Space Science conference at the University of Hertfordshire. Prof. Hood will present some of the work in a talk on Monday 20th April, supplemented by a poster by Dr. Vasilis Archontis on Thursday 23rd April, which will cover the model in more detail.

Recently, the X-Ray Telescope (XRT) on board the Hinode space mission was used to obtain the first images of the formation and eruption phase of a sigmoid at high resolution. These observations revealed that the structure of the sigmoid is complex: it consists of many, differently oriented, loops that all together form two opposite J-like bundles or an overall S-shape. They also showed that at the end of its life the sigmoid produces a 'flare' eruption.

Over the years a series of theoretical and numerical models have been proposed to explain the nature of sigmoids but until now there was no explanation on how such complex structures form, erupt and fade away.

[Ernest_at_the_Beach]

Running from top to bottom, these figures show the evolution of the sigmoid over three hours leading up to its final eruption. Columns 1 and 2 show results from the St Andrews model. The left column shows the strength of electric current predicted by the model and the central panel shows predictions of temperature. Column 3 shows the development of the sigmoid observed by Hinode. The model successfully predicts the shape of the sigmoid, internal structure and distribution of heat along its length. (Credit: NASA / STFC / ISAS / JAXA / A. Hood (St. Andrews), V. Archontis (St. Andrews))

[Tarpon]

How exactly did they test the model?

Like with AGW global warming, models are meaningless unless you have real world tests to verify. Otherwise,t hey are just so much math that produces pretty pictures.

I submit like with climate, we do not know how the processes of the sun really work.

[Ernest_at_the_Beach]

According to the text at #2....

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The model successfully predicts the shape of the sigmoid, internal structure and distribution of heat along its length.

[SunkenCiv]

Thanks Ernest_at_the_Beach.

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[Monkey Face]

I was just watching a segment today on what the sun is made of. It was really interesting. Of course, I suck up that stuff like my life depended on it!

[SunkenCiv]

The Sun is made of jalapeno flavored ice cream. Shh! That’s a secret.

[Monkey Face]

*kof*
*hak*

I won’t tell, for sure! Jalapenos are not on my menu!
(But ice cream is!)