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Post Info TOPIC: Sun 16.02.11


L

Posts: 130529
Date:
Sun 15.02.11
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Title: Velocity and Magnetic Transients Driven by the X2.2 White-Light Flare of 2011 February 15 in NOAA 11158
Authors: R. A. Maurya, Vema Reddy, A. Ambastha

The first X-class flare (X2.2) of the current solar cycle 24 occurred in Active Region (AR) NOAA 11158 during its central meridian passage on 2011 February 15. This two ribbon white-light flare was well observed by the Helioseismic and Magnetic Imager (HMI) on board Solar Dynamics Observatory. From the HMI high resolution observations, we detected magnetic and Doppler velocity transients appearing near the umbral boundary of the main sunspot during the peak phase of the flare. These transients were spatially and temporally associated with the white-light flare ribbons. Also, magnetic polarity went through sign reversal at the location of transients. On the other hand, Doppler velocity did not show such a reversal at the transient's location, while large magnitude enhancement occurred there. We attempt to explain the cause and observational characteristics of these transients on the basis of present theoretical models.

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RE: Sun 16.02.11
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Title: First Sunquake of Solar Cycle 24 Observed by Solar Dynamics Observatory
Authors: A.G. Kosovichev

The X2.2-class solar flare of February 15, 2011, produced a powerful `sunquake' event, representing a seismic response to the flare impact. The impulsively excited seismic waves formed a compact wavepacket travelling through the solar interior and appeared on the surface as expanding wave ripples. The Helioseismic and Magnetic Imager (HMI), instrument on SDO, observes variations of intensity, magnetic field and plasma velocity (Dopplergrams) on the surface of Sun almost uninterruptedly with high resolution (0.5 arcsec/pixel) and high cadence (45 sec). The flare impact on the solar surface was observed in the form of compact and rapid variations of the HMI observables (Doppler velocity, line-of-sight magnetic field and continuum intensity). These variations, caused by the impact of high-energy particles in the photosphere, formed a typical two-ribbon flare structure. The sunquake can be easily seen in the raw Dopplergram differences without any special data processing. The source of this quake was located near the outer boundary of a very complicated sunspot region, NOAA 1158, in a sunspot penumbra and at the penumbra boundary. This caused an interesting plasma dynamics in the impact region. I present some preliminary results of analysis of the near-real-time data from HMI, and discuss properties of the sunquake and the flare impact sources.

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Posts: 130529
Date:
Sunspot 11158
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A powerful solar eruption that has already disturbed radio communications in China could disrupt electrical power grids and satellites used on Earth in the next days, NASA said.
The massive sunspot, which astronomers say is the size of Jupiter, is the strongest solar flare in four years, NASA said Wednesday.

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L

Posts: 130529
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RE: Sun 16.02.11
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Sun unleashes huge solar flare towards Earth

The Sun has unleashed its strongest flare in four years, observers say.
The eruption is a so-called X-flare, the strongest type; such flares can affect communications on Earth.
Nasa's Solar Dynamics Observatory (SDO) spacecraft recorded an intense flash of extreme ultraviolet radiation emanating from a sunspot.

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Sunspot 11158
Sun160211b.jpg
Expand (135kb, 560 x 560)
Credit: SOHO/MDI

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