Letter to the Editor

Eruption of magnetic flux ropes during flux emergence

¹ School of Mathematics and Statistics, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9SS, UK e-mail: vasilis@mcs.st-and.ac.uk
² LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France e-mail: tibor.torok@obspm.fr

Received: 10 October 2008
Accepted: 5 November 2008

Abstract

Aims. We investigate the formation of flux ropes in a flux emergence region and their rise into the outer atmosphere of the Sun.

Methods. We perform 3D numerical experiments by solving the time-dependent and resistive MHD equations.

Results. A sub-photospheric twisted flux tube rises from the solar interior and expands into the corona. A flux rope is formed within the expanding field, due to shearing and reconnection of field lines at low atmospheric heights. If the tube emerges into a non-magnetized atmosphere, the flux rope rises, but remains confined inside the expanding magnetized volume. In contrast, if the expanding tube is allowed to reconnect with a pre-existing coronal field, the flux rope experiences a full eruption with a rise profile that is in qualitative agreement with erupting filaments and Coronal Mass Ejections.