A current sheet traced from the Sun to interplanetary space

¹ Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, PR China
e-mail: gpzhou@nao.cas.cn; wangjx@nao.cas.cn
² School of Physics, Peking University, Beijing 100871, PR China
e-mail: cjxiao@pku.edu.cn
³ Sydney Institute for Astronomy, School of Physics, University of Sydney, Australia
e-mail: michael.wheatland@sydney.edu.au
⁴ National Tsing Hua University, Taiwan 30013, PR China
e-mail: berserker0715@hotmail.com

Received: 9 September 2010
Accepted: 9 October 2010

Abstract

Context. Magnetic reconnection is a central concept for understanding solar activity, including filament eruptions, flares, and coronal mass ejections (CMEs). The existence of transverse and vertical current sheets, sites where reconnection takes place in the solar atmosphere, is frequently proposed as a precondition for flare/CME models, but is rarely identified in observations.

Aims. We aim at identifying a transverse current sheet that existed in the pre-CME structure and persisted from the CME solar source to interplanetary space.

Methods. STEREO A/B provide us a unique opportunity to calculate the interplanetary current sheets for the magnetic cloud. We analyze such a structure related to the fast halo CME of 2006 December 13 with assembled observations. A current sheet at the front of the magnetic cloud is analyzed to its origin in a transverse current sheet in the CME solar source, which can be revealed in the magnetic field extrapolations, XRT, and LASCO observations.

Results. An interplanetary current sheet is identified as coming from the CME solar source by carefully mapping and examining multiple observations from the Sun to interplanetary space, along with nonlinear force-free magnetic field extrapolations of the active region NOAA 10930.

Conclusions. The structure identified in the pre-flare state is a global transverse current sheet, which plays a role in the CME initiation, and propagates from the corona to interplanetary space.