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Solar Phys (2009) 258: 5367 DOI 10.1007/s11207-009-9392-z

Summary: Solar Phys (2009) 258: 5367
DOI 10.1007/s11207-009-9392-z
Evidence of Magnetic Helicity in Emerging Flux
and Associated Flare
R. Chandra B. Schmieder G. Aulanier
J.M. Malherbe
Received: 18 July 2008 / Accepted: 2 June 2009 / Published online: 26 June 2009
Springer Science+Business Media B.V. 2009
Abstract The aim of this paper is to look at the magnetic helicity structure of an emerg-
ing active region and show that both emergence and flaring signatures are consistent with
a same sign for magnetic helicity. We present a multiwavelength analysis of an M1.6 flare
occurring in the NOAA active region 10365 on 27 May 2003, in which a large new bipole
emerges in a decaying active region. The diverging flow pattern and the "tongue" shape of
the magnetic field in the photosphere with elongated polarities are highly suggestive of the
emergence of a twisted flux tube. The orientation of these tongues indicates the emergence
of a flux tube with a right-hand twist (i.e., positive magnetic helicity). The flare signatures
in the chromosphere are ribbons observed in H by the MSDP spectrograph in the Meudon
solar tower and in 1600 by TRACE. These ribbons have a J shape and are shifted along the
inversion line. The pattern of these ribbons suggests that the flare was triggered by magnetic
reconnection at coronal heights below a twisted flux tube of positive helicity, corresponding


Source: Aulanier, Guillaume - Observatoire de Paris


Collections: Physics