The emergence of weakly twisted magnetic fields in the Sun
Abstract
We have studied the emergence of a weakly twisted magnetic flux tube from the upper convection zone into the solar atmosphere. It is found that the rising magnetized plasma does not undergo the classical, single Ω-shaped loop emergence, but it becomes unstable in two places, forming two magnetic lobes that are anchored in small-scale bipolar structures at the photosphere, between the two main flux concentrations. The two magnetic lobes rise and expand into the corona, forming an overall undulating magnetic flux system. The dynamical interaction of the lobes results in the triggering of high-speed and hot jets and the formation of successive cool and hot loops that coexist in the emerging flux region. Although the initial emerging field is weakly twisted, a highly twisted magnetic flux rope is formed at the low atmosphere, due to shearing and reconnection. The new flux rope (hereafter post-emergence flux rope) does not erupt. It remains confined by the overlying field. Although there is no ejective eruption of the post-emergence rope, it is found that a considerable amount of axial and azimuthal flux is transferred into the solar atmosphere during the emergence of the magnetic field.
Citation
Archontis , V , Hood , A W & Tsinganos , K 2013 , ' The emergence of weakly twisted magnetic fields in the Sun ' , Astronomical Journal , vol. 778 , no. 1 , 42 . https://doi.org/10.1088/0004-637X/778/1/42
Publication
Astronomical Journal
Status
Peer reviewed
ISSN
0004-6256Type
Journal article
Rights
© 2013. The American Astronomical Society. All rights reserved.
Description
The simulations were performed on the STFC and SRIF funded UKMHD cluster, at the University of St Andrews. K.T. and V.A. acknowledge EU support (IEF-272549 grant).Collections
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.