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TOPIC: The Sun
Blobrana


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RE: The Sun
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Dramatic eruptions on the Sun have been captured in rare footage by two Nasa spacecraft.
Filmed over two days, the images show large glowing clouds of gas bursting from the Sun's surface and held aloft by the star's twisted magnetic fields.
These huge solar prominences are several times larger than the Earth and are caused by the solar activity cycle. It is one of the most spectacular events that the twin STEREO (Solar TErrestrial RElations Observatory) craft have observed.

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Blobrana


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3 Month Solar Burst Study



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Blobrana


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'Quiet' Sun continues to affect Earth
The Sun can lash the Earth with powerful winds that can disrupt communications, aviation and power lines even when it is in the quiet phase of its 11-year solar cycle, say US scientists.
Observers have traditionally used the number of sunspots on the surface of the Sun to measure its activity. The number of sunspots reaches a peak at what is called the solar maximum and then declines to reach a minimum during a cycle.

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Blobrana


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Solar corona
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Tiny Flares Responsible for Outsized Heat of Sun's Atmosphere

"Why is the sun's corona so darned hot?" - James Klimchuk, an astrophysicist at the Goddard Space Flight Centre's Solar Physics Laboratory in Greenbelt, Md.

The mystery of why temperatures in the solar corona, the sun's outer atmosphere, soar to several million degrees Kelvin (K) - much hotter than temperatures nearer the sun's surface - has puzzled scientists for decades. New observations made with instruments aboard Japan's Hinode satellite reveal the culprit to be nanoflares.
Nanoflares are small, sudden bursts of heat and energy.

"They occur within tiny strands that are bundled together to form a magnetic tube called a coronal loop" - James Klimchuk.

Coronal loops are the fundamental building blocks of the thin, translucent gas known as the sun's corona.

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Blobrana


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Le chauffage du vent solaire se situe à léchelle électronique
Des chercheurs du laboratoire de Physique des Plasmas, en analysant des données provenant des satellites Cluster (ESA), explicitent le processus du chauffage du vent solaire. L'énergie engendrée par la turbulence est transférée des grandes échelles, 100 km, aux petites échelles électroniques, 10 km. Ceci permettrait d'expliquer les processus d'accélération des électrons, processus que l'on rencontre dans la couronne solaire, mais aussi dans différents environnements astronomiques.

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Blobrana


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Czech scientists take photos of solar corona
Czech scientists have taken the pictures of the solar corona which were carried on the cover of the latest issue of the prestigious international journal of Nature this week.

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Blobrana


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With the sun at its lowest activity level in nearly 100 years, scientists are taking advantage of its quiet state to ferret out some of the more subtle -- and occasionally insidious -- ways the sun impacts Earth's climate and atmosphere.
Solar flares and other geomagnetic events on the sun vary in frequency over an 11-year cycle. Now at an unusually low "minimum" in that cycle, the sun is expected to peak in activity in 2013.

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Blobrana


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Fibrils
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Title: Bright fibrils in Ca II K
Authors: A. Pietarila, J. Hirzberger, V. Zakharov, S.K.Solanki

Context: Except for the Ca II resonance lines, fibrils are ubiquitously present in most high-resolution observations of chromospheric lines. Aims: We show that fibrils are also a prevailing feature in Ca II K, provided the spatial-resolution is sufficiently high. Methods: We present high spatial resolution observations of an active region in the Ca I} K line from the Swedish Solar Telescope. Through a comparison between photospheric intensity and magnetic field data, we study the connection between bright chromospheric fibrils and photospheric structures. Additionally, using Fourier analysis we study how the fibrils are linked to the observed dynamics. Results: We find that very narrow, bright fibrils are a prevailing feature over large portions of the observed field. We also find a clear connection between the fibril footpoints and photospheric magnetic features. We show that the fibrils play two distinct roles in the observed dynamics: depending on their location they can act as a canopy suppressing oscillations or they can channel low-frequency oscillations into the chromosphere. Conclusions: The Ca II K fibrils share many characteristics with fibrils observed in other chromospheric lines, but some features, such as the very small widths, are unique to these observations.

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Blobrana


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After a prolonged lull in activity, sunspots, and their associated solar storms, are on the rise again.

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Blobrana


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The sun's new solar cycle, which is thought to have begun in December 2008, will be the weakest since 1928. That is the nearly unanimous prediction of a panel of international experts, some of whom maintain that the sun will be more active than normal.
But even a mildly active sun could still generate its fair share of extreme storms that could knock out power grids and space satellites.

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