Stellar flares and the dark energy of CMEs

TL;DR

This paper explores the relationship between stellar flares and coronal mass ejections (CMEs), proposing magnetic suppression as a key factor in stellar magnetic activity and its impact on planetary atmospheres.

Contribution

It introduces the concept of magnetic suppression of CMEs on active stars, explaining how strong magnetic fields can prevent CMEs despite large flares.

Findings

Large stellar flares emit significantly less X-ray energy than associated CMEs.

Magnetic suppression can prevent CMEs in active stars with strong magnetic fields.

Potential for massive CMEs to impact planetary atmospheres despite suppression.

Abstract

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.