scostep 2010 (stp12) - Leibniz-Institut für Atmosphärenphysik an der ...

Flares, coronal mass ejections, and magnetic clouds from a mixed helicity active region
Mandrini Cristina H. 1 , Chandra Ramesh 2 , Pariat Etienne 2 , Schmieder Brigitte 2 , Démoulin Pascal 2 ,
Torok Tibor 2 , Uddin Wahab 3
1 Instituto de Astronomía y Física del Espacio, CONICET-UBA, CC 67 Suc. 28, 1428 Buenos Aires,
Argentina, 2 Observatoire de Paris, LESIA, UMR8109 (CNRS), F-92195, Meudon Principal Cedex,
France, 3 Aryabhatta Research Institute of Observational Science, ARIES, Nainital - 263 129, India
On 18 and 20 November 2003, active region (AR) 10501 produced a series of M flares all of
them associated with coronal mass ejections (CMEs), some of which were identified as the
source of subsequent magnetic clouds at 1 AU.
The particularity of this AR is that while observational tracers of the magnetic helicity sign
indicate that the large scale field in the region had negative magnetic helicity, the MC
associated to the most intense flare/CME on November 18 showed the opposite sign.
Furthermore, the filaments observed on November 20 present morphological characteristics
that correspond to a negative magnetic helicity sign, the rotation of the polarities of an
emerging bipole indicate negative magnetic helicity sign injection; however, the flare ribbons
observed after two homologous events can be connected either by field lines computed using
a positive or a negative helicity sign magnetic field.
We combine Halpha, EUV, hard X-rays, and magetic field data analysis with magnetic field
modeling, topology, and magnetic helicity injection computations to understand the origin of
the helicity sign discrepancies and the initiation scenario of the ejective events.