Please use this identifier to cite or link to this item:
|Title:||Recurrent flares in active region NOAA 11283||Authors:||ROMANO, Paolo
Guglielmino, S. L.
de Lauretis, M.
Del Moro, D.
Kordi, A. S.
Landi Degl'Innocenti, E.
Marcucci, M. F.
|Issue Date:||2015||Journal:||ASTRONOMY & ASTROPHYSICS||Number:||582||First Page:||A55||Abstract:||Context. Flares and coronal mass ejections (CMEs) are solar phenomena that are not yet fully understood. Several investigations have been performed to single out their related physical parameters that can be used as indices of the magnetic complexity leading to their occurrence. <BR /> Aims: In order to shed light on the occurrence of recurrent flares and subsequent associated CMEs, we studied the active region NOAA 11283 where recurrent M and X GOES-class flares and CMEs occurred. <BR /> Methods: We use vector magnetograms taken by HMI/SDO to calculate the horizontal velocity fields of the photospheric magnetic structures, the shear and the dip angles of the magnetic field, the magnetic helicity flux distribution, and the Poynting fluxes across the photosphere due to the emergence and the shearing of the magnetic field. <BR /> Results: Although we do not observe consistent emerging magnetic flux through the photosphere during the observation time interval, we detected a monotonic increase of the magnetic helicity accumulated in the corona. We found that both the shear and the dip angles have high values along the main polarity inversion line (PIL) before and after all the events. We also note that before the main flare of X2.1 GOES class, the shearing motions seem to inject a more significant energy than the energy injected by the emergence of the magnetic field. <BR /> Conclusions: We conclude that the very long duration (about 4 days) of the horizontal displacement of the main photospheric magnetic structures along the PIL has a primary role in the energy release during the recurrent flares. This peculiar horizontal velocity field also contributes to the monotonic injection of magnetic helicity into the corona. This process, coupled with the high shear and dip angles along the main PIL, appears to be responsible for the consecutive events of loss of equilibrium leading to the recurrent flares and CMEs. <P />A movie associated to Fig. 4 is available in electronic form at <A href="http://www.aanda.org/10.1051/0004-6361/201525887/olm">http://www.aanda.org||Acknowledgments:||The authors wish to thank the referee for his/her very useful comments and suggestions, which led to a sounder version of the article. This research work has received funding from the European Commissions Seventh Framework Programme under the grant agreements No. 284461 (eHEROES project), No. 312495 (SOLARNET project), No. 606862 (F-Chroma project). This research work is partly supported by the Italian MIUR-PRIN grant 2012P2HRCR on The active Sun and its effects on Space and Earth climate and by Space Weather Italian COmmunity (SWICO) Research Program. The research by the KSU astronomy unit – A.E. and A.S.K. – was supported by King Saud University, Deanship of Scientific Research, College of Science Research Center.||URI:||http://hdl.handle.net/20.500.12386/24062||URL:||https://www.aanda.org/articles/aa/abs/2015/10/aa25887-15/aa25887-15.html||ISSN:||0004-6361||DOI:||10.1051/0004-6361/201525887||Bibcode ADS:||2015A&A...582A..55R||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
Show full item record
Files in This Item:
|romano_aa25887-15.pdf||PDF editoriale||3.83 MB||Adobe PDF||View/Open|
checked on Sep 24, 2020
checked on Sep 24, 2020
Items in DSpace are published in Open Access, unless otherwise indicated.