The rise of kink-unstable magnetic flux tubes in the solar convection zone

Citation
Y. Fan et al., The rise of kink-unstable magnetic flux tubes in the solar convection zone, ASTROPHYS J, 505(1), 1998, pp. L59-L63
Citations number
19
Categorie Soggetti
Space Sciences
Journal title
ASTROPHYSICAL JOURNAL
ISSN journal
0004637X → ACNP
Volume
505
Issue
1
Year of publication
1998
Part
2
Pages
L59 - L63
Database
ISI
SICI code
0004-637X(19980920)505:1<L59:TROKMF>2.0.ZU;2-7
Abstract
We report preliminary results of a three-dimensional simulation of the buoy ant rise of a strongly twisted, kink-unstable magnetic flux tube through a gravitationally stratified layer representing the solar convection zone. Th e numerical calculations employ the well-known anelastic approximation, whi ch is suitable for studying slow, subsonic dynamical processes in the press ure-dominated, high-beta plasma of the solar interior. This Letter investig ates the case in which the initial twist of the buoyant flux tube is suffic iently high that the e-folding growth times of the unstable kink modes are short in comparison to the rise time of the flux tube. Our simulation shows that the flux tube becomes kinked and that the top portion of the flux tub e evolves into a buckled shape with the tube axis being deflected by more t han 90 degrees from its original orientation. We suggest that the emergence of this buckled flux tube can give rise to a compact magnetic bipole with polarity order inverted from Hale's polarity law, similar to the configurat ion often seen in delta spots.