Flares we observe on stars in white light, UV or soft X-rays are probably harbingers of coronal mass ejections (CMEs). If we use the Sun as a guide, large stellar flares will dissipate two orders of magnitude less X-ray radiative energy than the kinetic energy in the associated CME. Since coronal emission on active stars appears to be dominated by flare activity, CMEs pose a quandary for understanding the fraction of their energy budget stars can spend on magnetic activity. One answer is magnetic suppression of CMEs, in which the strong large-scale fields of active stars entrap and prevent CMEs unless their free energy exceeds a critical value. The CME-less flaring active region NOAA 2192 presents a possible solar analogue of this. Monster CMEs will still exist, and have the potential to ravage planetary atmospheres.
@article{arxiv.1610.05185,
title = {Stellar flares and the dark energy of CMEs},
author = {Jeremy J. Drake and Ofer Cohen and Cecilia Garraffo and Vinay Kashyap},
journal= {arXiv preprint arXiv:1610.05185},
year = {2016}
}
Comments
6 pages, to appear in Proceedings of IAU Symposium No. 320