Slingshot prominences: coronal structure, mass loss and spin down

TL;DR

This paper introduces a new method to map the coronal magnetic field of young stars using slingshot prominences as markers, revealing insights into stellar mass loss and spin-down processes.

Contribution

It demonstrates the effectiveness of using prominence observations and magnetic field extrapolations to study stellar coronal structures and their impact on stellar evolution.

Findings

Potential field extrapolation matches observed prominence features.

Up to 50% of prominence mass can transit the star in aligned systems.

Mass and angular momentum loss rates vary widely, approaching stellar wind levels.

Abstract

The structure of a star's coronal magnetic field is a fundamental property that governs the high-energy emission from the hot coronal gas and the loss of mass and angular momentum in the stellar wind. It is, however, extremely difficult to measure. We report a new method to trace this structure in rapidly-rotating young convective stars, using the cool gas trapped on coronal field lines as markers. This gas forms "slingshot prominences" which appear as transient absorption features in H-$\alpha$. By using different methods of extrapolating this field from the surface measurements, we determine locations for prominence support and produce synthetic H-$\alpha$ stacked spectra. The absorption features produced with a potential field extrapolation match well this those observed, while those from a non-potential field do not. In systems where the rotation and magnetic axes are well aligned, up to $50\%$ of the prominence mass may transit the star and so produces a observable feature. This fraction may fall as low as $~2\%$ in very highly inclined systems. Ejected prominences carry away mass and angular momentum at rates that vary by two orders of magnitude, but which may approach those carried by the stellar wind.