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Post Info TOPIC: Sun 19.10.14


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Solar Active Region 12192
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Title: Confined Flares in Solar Active Region 12192 from 2014 October 18 to 29
Author: Huadong Chen, Jun Zhang, Suli Ma, Shuhong Yang, Leping Li, Xin Huang, Junmin Xiao

Using the observations from the Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) aboard the Solar Dynamics Observatory (SDO), we investigate six X-class and twenty-nine M-class flares occurring in solar active region (AR) 12192 from October 18 to 29. Among them, thirty (including six X- and twenty-four M-class) flares originated from the AR core and the other five M-flares appeared at the AR periphery. Four of the X-flares exhibited similar flaring structures, indicating they were homologous flares with analogous triggering mechanism. The possible scenario is: photospheric motions of emerged magnetic fluxes lead to shearing of the associated coronal magnetic field, which then yields a tether-cutting favourable configuration. Among the five periphery M-flares, four were associated with jet activities. The HMI vertical magnetic field data show that the photospheric fluxes of opposite magnetic polarities emerged, converged and canceled with each other at the footpoints of the jets before the flares. Only one M-flare from the AR periphery was followed by a coronal mass ejection (CME). From October 20 to 26, the mean decay index of the horizontal background field within the height range of 40-105 Mm is below the typical threshold for torus instability onset. This suggests that a strong confinement from the overlying magnetic field might be responsible for the poor CME production of AR 12192.

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Date:
Sunspot 12192
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Title: Oscillating light wall above a sunspot light bridge
Author: Shuhong Yang, Jun Zhang, Fayu Jiang, Yongyuan Xiang

With the high tempo-spatial Interface Region Imaging Spectrograph 1330 {\AA} images, we find that many bright structures are rooted in the light bridge of NOAA 12192, forming a light wall. The light wall is brighter than the surrounding areas, and the wall top is much brighter than the wall body. The New Vacuum Solar Telescope H alpha and the \emph{Solar Dynamics Observatory} 171 {\AA} and 131 {\AA} images are also used to study the light wall properties. In 1330 {\AA}, 171 {\AA}, and 131 {\AA}, the top of the wall has a higher emission, while in the H alpha line, the wall top emission is very low. The wall body corresponds to bright areas in 1330 {\AA} and dark areas in the other lines. The top of the light wall moves upward and downward successively, performing oscillations in height. The deprojected mean height, amplitude, oscillation velocity, and the dominant period are determined to be 3.6 Mm, 0.9 Mm, 15.4 km s-1, and 3.9 min, respectively. We interpret the oscillations of the light wall as the leakage of p-modes from below the photosphere. The constant brightness enhancement of the wall top implies the existence of some kind of atmospheric heating, e.g., via the persistent small-scale reconnection or the magneto-acoustic waves. In another series of 1330 {\AA} images, we find that the wall top in the upward motion phase is significantly brighter than in the downward phase. This kind of oscillations may be powered by the energy released due to intermittent impulsive magnetic reconnection.

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RE: Sun 19.10.14
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Title: Why Is the Great Solar Active Region 12192 CME-Poor?
Author: Xudong Sun, Monica G. Bobra, J. Todd Hoeksema, Yang Liu, Yan Li, Chenglong Shen, Sebastien Couvidat, Aimee A. Norton, George H. Fisher

Solar active region (AR) 12192 of October 2014 hosts the largest sunspot group in 24 years. It is the most prolific flaring site of Cycle 24, but surprisingly produced no coronal mass ejection (CME) from the core region during its disk passage. Here, we study the magnetic conditions that prevented eruption and the consequences that ensued. We find AR 12192 to be "big but mild"; its core region exhibits weaker non-potentiality, stronger overlying field, and smaller flare-related field changes compared to two other major flare-CME-productive ARs (11429 and 11158). These differences are present in the intensive-type indices (e.g., means) but generally not the extensive ones (e.g., totals). AR 12192's large amount of magnetic free energy does not translate into CME productivity. The unexpected behavior suggests that AR eruptiveness is limited by some relative measure of magnetic non-potentiality over the restriction of background field, and that confined flares may leave weaker photospheric and coronal imprints compared to their eruptive counterparts.

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NASA's SDO Observes an X-class Solar Flare

The sun emitted a significant solar flare, peaking at 1:01 a.m. EDT on Oct. 19, 2014. NASA's Solar Dynamics Observatory, which is always observing the sun, captured an image of the event. Solar flares are powerful bursts of radiation.
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Sunspot 12192
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Sunspot 12192 captured with a 100mm f5/ Helios refractor and vesta pro webcam + 2x Barlow lens + solar filter.

Capture 19_10_2014 13_34_12Capture 19_10_2014 13_32_08
  High contrast processed.


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RE: Sun 19.10.14
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Two panel photomosaic of sunspots 12192, 12187 and 12185 (western edge).

Capture 19_10_2014 12_41_23mosaic 
  


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 Two panel photomosaic of sunspots 12192, 12187 and 12185 (western edge) captured with a 100mm f5/ acromatic refractor and vesta pro webcam.

Capture 19_10_2014 08_49_17_mosaic 
 Cloudy, Low in sky, bad seeing 


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Three panel photomosaic captured with a 100mm f5/ Helios refractor and vesta pro webcam

Capture 19_10_2014 08_48_11mosaicPicture 001
  


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