A Monster CME Obscuring A Demon Star Flare

TL;DR

This study models a Coronal Mass Ejection (CME) as the cause of X-ray absorption during a 1997 superflare on Algol, estimating its properties and energy based on observational data and solar CME relations.

Contribution

It presents a detailed analysis of a stellar CME associated with a superflare, using the ice-cream cone model and magnetic energy considerations to estimate CME parameters.

Findings

CME likely caused the observed X-ray absorption decay.

Estimated CME mass range: 2×10^{21}–2×10^{22} g.

Estimated CME kinetic energy range: 7×10^{35}–3×10^{38} erg.

Abstract

We explore the scenario of a Coronal Mass Ejection (CME) being the cause of the observed continuous X-ray absorption of the August 30 1997 superflare on the eclipsing binary Algol (the Demon Star). The temporal decay of the absorption is consistent with absorption by a CME undergoing self-similar evolution with uniform expansion velocity. We investigate the kinematic and energetic properties of the CME using the ice-cream cone model for its three-dimensional structure in combination with the observed profile of the hydrogen column density decline with time. Different physically justified length scales were used that allowed us to estimate lower and upper limits of the possible CME characteristics. Further consideration of the maximum available magnetic energy in starspots leads us to quantify its mass as likely lying in the range $2\times 10^{21}$-$2\times 10^{22}$ g and kinetic energy in the range $7\times 10^{35}$-$3\times 10^{38}$ erg. The results are in reasonable agreement with extrapolated relations between flare X-ray fluence and CME mass and kinetic energy derived for solar CMEs.