Simulating stellar coronal rain and slingshot prominences

TL;DR

This study uses numerical simulations to explore how stellar rotation influences the formation of coronal rain and slingshot prominences, revealing distinct behaviors and mass-loss components in different rotational regimes.

Contribution

It introduces a detailed simulation framework that distinguishes between slow and fast stellar rotation effects on coronal condensations and prominence formation.

Findings

Condensations form below the co-rotation radius in slow rotators.

Fast rotators develop slingshot prominences and periodic ejections.

Cold gas constitutes about 51% of the coronal mass in fast rotators.

Abstract

We have numerically demonstrated that simulated cool star coronae naturally form condensations. If the star rotates slowly, with a co-rotation radius greater than the Alfv\'{e}n radius (i.e. $R_{\mathrm{K}} > R_{\mathrm{A}}$), these condensations will form below the co-rotation radius $R_{\mathrm{K}}$ and simply fall back to the stellar surface as coronal rain. If, however, the star is more rapidly rotating, ($R_{\mathrm{K}} < R_{\mathrm{A}}$), not only rain will form but also ``slingshot prominences''. In this case, condensations collect into a large mass reservoir around the co-rotation radius, from which periodic centrifugal ejections occur. In this case, some $51\%$ of the coronal mass is cold gas, either in rain or prominences. We find that 21\% of the mass lost by our simulated fast rotating star is cold gas. Studies of stellar mass-loss from the hot wind do not consider this component of the wind and therefore systematically underestimate mass-loss rates of these stars. Centrifugal ejections happen periodically, between every 7.5 - 17.5 hours with masses clustering around $10^{16}$ g, These results agree well with observational statistics. Contrasting the fast and slow rotating magnetospheres, we find that there are two distinct types of solutions, high lying and low lying loops. Low lying loops only produce coronal rain whereas high lying loops produce both rain and slingshots.