Stellar differential rotation and coronal time-scales
View/ Open
Date
10/2014Funder
Grant ID
ST/K000950/1
ST/J001651/1
RPG-305
Keywords
Metadata
Show full item recordAbstract
We investigate the time-scales of evolution of stellar coronae in response to surface differential rotation and diffusion. To quantify this, we study both the formation time and lifetime of a magnetic flux rope in a decaying bipolar active region. We apply a magnetic flux transport model to prescribe the evolution of the stellar photospheric field, and use this to drive the evolution of the coronal magnetic field via a magnetofrictional technique. Increasing the differential rotation (i.e. decreasing the equator-pole lap time) decreases the flux rope formation time. We find that the formation time is dependent upon the lap time and the surface diffusion time-scale through the relation tau_Form ∝ &surd;{tau_Laptau_Diff}. In contrast, the lifetimes of flux ropes are proportional to the lap time (tauLife∝tauLap). With this, flux ropes on stars with a differential rotation of more than eight times the solar value have a lifetime of less than 2 d. As a consequence, we propose that features such as solar-like quiescent prominences may not be easily observable on such stars, as the lifetimes of the flux ropes which host the cool plasma are very short. We conclude that such high differential rotation stars may have very dynamical coronae.
Citation
Gibb , G P S , Jardine , M M & Mackay , D H 2014 , ' Stellar differential rotation and coronal time-scales ' , Monthly Notices of the Royal Astronomical Society , vol. 433 , no. 4 , pp. 3251-3259 . https://doi.org/10.1093/mnras/stu1415
Publication
Monthly Notices of the Royal Astronomical Society
Status
Peer reviewed
ISSN
0035-8711Type
Journal article
Rights
© 2014. The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. All rights reserved.
Description
GPSG would like to thank the STFC for financial support. DHM would like to thank the STFC and the Leverhulme Trust for financial support.Collections
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.