Planet-induced radio emission from the coronae of M dwarfs : the case of Prox Cen and AU Mic
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There have recently been detections of radio emission from low-mass stars, some of which are indicative of star-planet interactions. Motivated by these exciting new results, in this paper we present Alfvén wave-driven stellar wind models of the two active planet-hosting M dwarfs Prox Cen and AU Mic. Our models incorporate large-scale photospheric magnetic field maps reconstructed using the Zeeman-Doppler Imaging method. We obtain a mass-loss rate of 0.25 Ṁ⊙ for the wind of Prox Cen. For the young dwarf AU Mic, we explore two cases: a low and high mass-loss rate. Depending on the properties of the Alfvén waves which heat the corona in our wind models, we obtain mass-loss rates of 27 and 590 Ṁ⊙ for AU Mic. We use our stellar wind models to assess the generation of electron cyclotron maser instability emission in both systems, through a mechanism analogous to the sub-Alfvénic Jupiter-Io interaction. For Prox Cen we do not find any feasible scenario where the planet can induce radio emission in the star’s corona, as the planet orbits too far from the star in the super-Alfvénic regime. However, in the case that AU Mic has a stellar wind mass-loss rate of 27 Ṁ⊙, we find that both planets b and c in the system can induce radio emission from ∼10 MHz – 3 GHz in the corona of the host star for the majority of their orbits, with peak flux densities of ∼10 mJy. Detection of such radio emission would allow us to place an upper limit on the mass-loss rate of the star.
Kavanagh , R D , Vidotto , A A , Klein , B , Jardine , M M , Donati , J-F & Fionnagáin , D Ó 2021 , ' Planet-induced radio emission from the coronae of M dwarfs : the case of Prox Cen and AU Mic ' , Monthly Notices of the Royal Astronomical Society , vol. Advance Article . https://doi.org/10.1093/mnras/stab929
Monthly Notices of the Royal Astronomical Society
Copyright © 2021 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/stab929.
DescriptionRDK acknowledges funding received from the Irish Research Council (IRC) through the Government of Ireland Postgraduate Scholarship Programme. AAV acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 817540, ASTROFLOW). BK acknowledges funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 865624, GPRV). MMJ acknowledges support from STFC consolidated grant number ST/R000824/1. JFD and BK acknowledge the ERC for grant agreement No 740651, NewWorlds. DOF acknowledges funding from the IRC Government of Ireland Postdoctoral Fellowship Programme. We acknowledge the Irish Centre for High-End Computing (ICHEC) for providing the computational facilities used to perform the simulations published in this work.
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