Slingshot prominences : coronal structure, mass-loss and spin-down
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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-α. By using different methods of extrapolating this field from the surface measurements, we determine locations for prominence support and produce synthetic H-α 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.
Jardine , M , Cameron , A C , Donati , J -F & Hussain , G A J 2020 , ' Slingshot prominences : coronal structure, mass-loss and spin-down ' , Monthly Notices of the Royal Astronomical Society , vol. 491 , no. 3 , stz3173 , pp. 4076-4088 . https://doi.org/10.1093/mnras/stz3173
Monthly Notices of the Royal Astronomical Society
Copyright © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1093/mnras/stz3173
DescriptionMJ and ACC acknowledge support from STFC consolidated grant number ST/R000824/1. JFD acknowledges funding from the European Research Council (ERC) under the H2020 research and innovation programme (grant agreement 740651 NewWorlds).
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