ABSTRACT
Nandita Srivastavanandita@prl.res.in
Udaipur Solar Observatory, PRL
| Title : | On the dynamics of the largest active region of the solar cycle 24 |
| Abstract | |
| AR12192 is the largest region of the solar cycle 24 and it underwent a noticeable growth and produced 6 X-class flares, 22 M class flares, and 53 C-class flares in the course of its disc passage. But the most peculiar fact of this AR is that it was associated with only one CME in spite of producing several X-class flares. We carry out a comparative study between the eruptive and non-eruptive flares produced by AR 12192. We find that the magnitude of abrupt and permanent changes in the horizontal magnetic field and Lorentz force are smaller in case of the confined flares compared to the eruptive one. We find the flare related morphological changes to be weaker during the confined flares, whereas the eruptive flare exhibits a rapid and permanent disappearance of penumbral area away from the magnetic neutral line after the flare. Furthermore, from the extrapolated nonlinear force-free magnetic field, we examine the overlying coronal magnetic environment over the eruptive and non-eruptive zones of the AR. We find the critical decay index for the onset of torus instability was achieved at a lower height over the eruptive flaring region, than for the noneruptive core area. These results suggest that the decay rate of the gradient of overlying magnetic field strength may play a decisive role to determine the CME productivity of the AR. As an extension of the above work, we also study magnetic field changes in the AR which produce recurrent eruptive flares and CMEs within a day, thereby leading to CME-CME interaction in the heliosphere. In particular, this will be helpful to understand the conditions leading to an energetic and fast CME following a slow CME from the same active region. |
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