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Post Info TOPIC: Sun 13.09.11


L

Posts: 131433
Date:
RE: Sun 13.09.11
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Title: Unusual Filaments Inside the Umbra
Authors: Lucia Kleint, Alberto Sainz Dalda

We analyse several unusual filamentary structures, which appeared in the umbra of one of the sunspots in AR 11302. They do not resemble typical light bridges, neither in morphology, nor in evolution. We analyse data from SDO/HMI to investigate their temporal evolution, Hinode/SP for photospheric inversions, IBIS for chromospheric imaging, and SDO/AIA for the overlying corona. Photospheric inversions reveal a horizontal, inverse Evershed flow along these structures, which we call umbral filaments. Chromospheric images show brightenings and energy dissipation, while coronal images indicate that bright coronal loops seem to end in these umbral filaments. These rapidly evolving features do not seem to be common, and are possibly related to the high flare-productivity of the active region. Their analysis could help to understand the complex evolution of active regions.

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L

Posts: 131433
Date:
Sunspot 11295
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Title: Observational Evidence of Sausage-Pinch Instability in Solar Corona by SDO/AIA
Authors: A.K. Srivastava, R. Erdélyi, Durgesh Tripathi, V. Fedun, N.C. Joshi, P. Kayshap

We present the first observational evidence of the evolution of sausage-pinch instability in Active Region 11295 during a prominence eruption using data recorded on 12 September 2011 by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). We have identified a magnetic flux tube visible in AIA 304 angstrom that shows curvatures on its surface with variable cross-sections as well as enhanced brightness. These curvatures evolved and thereafter smoothed out within a time-scale of a minute. The curved locations on the flux tube exhibit a radial outward enhancement of the surface of about 1-2 Mm (factor of 2 larger than the original thickness of the flux tube) from the equilibrium position. AIA 193 angstrom snapshots also show the formation of bright knots and narrow regions inbetween at the four locations as that of 304 angstrom along the flux tube where plasma emission is larger compared to the background. The formation of bright knots over an entire flux tube as well as the narrow regions in < 60 s may be the morphological signature of the sausage instability. We also find the flows of the confined plasma in these bright knots along the field lines, which indicates the dynamicity of the flux tube that probably causes the dominance of the longitudinal field component over short temporal scales. The observed longitudinal motion of the plasma frozen in the magnetic field lines further vanishes the formed curvatures and plasma confinements as well as growth of instability to stabilise the flux tube.

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L

Posts: 131433
Date:
Sun 29.09.11
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Sunspot 11302, with a trail of smaller sunspots, (11305, 11306 and 11307 which has recently emerged over the Sun's eastern limb).

Sun290911b.gif
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Credit: SOHO/MDI



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L

Posts: 131433
Date:
Sun 28.09.11
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Sunspot 11302 at the center of the solar disk

Sun280911b.gif
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Credit: SOHO/MDI



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L

Posts: 131433
Date:
Sun 27.09.11
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Sunspot 11302.

Sun270911b.gif
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Credit: SOHO/MDI



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L

Posts: 131433
Date:
Sun 25.09.11
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A small sunspot has appeared over the Sun's eastern limb.

Sun2540911b.gif
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Credit: SOHO/MDI



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L

Posts: 131433
Date:
Sun 24.09.11
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Sunspot 11295 is just about to disappear over the Sun's western limb.

Sun240911b.gif
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Credit: SOHO/MDI



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L

Posts: 131433
Date:
Sun 19.09.11
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Sunspot 11289 is just about to disappear over the Sun's western limb, while a new sunspot, 11301, has appeared on the Sun's opposite limb.

Sun190911b.gif
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Credit: SOHO/MDI



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L

Posts: 131433
Date:
Sun 18.09.11
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Sunspots 11296, 11295, 11298, 11299 and 11289 which is about to disappear over the Sun's western limb. A new sunspot appears to be emerging over the Sun's northeastern limb.

Sun180911b.gif
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Credit: SOHO/MDI



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L

Posts: 131433
Date:
Sun 14.09.11
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Sunspots are clearly visible in small telescopes (fitted with suitable solar filters).

sun140911b.gif
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Credit: SOHO/MDI



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