Magnetized winds of M-type stars and star-planet magnetic interactions: uncertainties and modeling strategy

Abstract

M-type stars are the most common stars in the universe. They are ideal hosts for the search of exoplanets in the habitable zone (HZ), as their small size and low temperature make the HZ much closer in than their solar twins. Harboring very deep convective layers, they also usually exhibit very intense magnetic fields. Understanding their environment, in particular their coronal and wind properties, is thus very important, as they might be very different from what is observed in the solar system. The mass loss rate of M-type stars is poorly known observationally, and recent attempts to estimate it for some of them (TRAPPIST-1, Proxima Cen) can vary by an order of magnitude. In this work, we revisit the stellar wind properties of M-dwarfs in the light of the latest estimates of $\dot{M}$ through Lyman-$\alpha$ absorption at the astropause and slingshot prominences. We outline a modeling strategy to estimate the mass loss rate, radiative loss and wind speed, with uncertainties, based on an Alfvén wave driven stellar wind model. We find that it is very likely that several TRAPPIST-1 planets lie within the Alfvén surface, which imply that these planets experience star-planet magnetic interactions (SPMI). We also find that SPMI between Proxima Cen b and its host star could be the reason of recently observed radio emissions.

15 pages, 9 figures, published in ApJ, typos corrected in the model description

References in corpus (34)

• PLUTO: a Numerical Code for Computational Astrophysics
• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• CHIANTI -- an atomic database for emission lines -- Paper XVI: Version 10, further extensions
• The effect of magnetic topology on thermally-driven winds: towards a general formulation of the braking law
• Magnetism, rotation, and nonthermal emission in cool stars -- Average magnetic field measurements in 292 M dwarfs
• XUV-driven mass loss from extrasolar giant planets orbiting active stars
• The Space Weather of Proxima Centauri b
• Reconnaissance of the TRAPPIST-1 exoplanet system in the Lyman-$\alpha$ line
• Temporal evolution of the high-energy irradiation and water content of TRAPPIST-1 exoplanets
• The Threatening Environment of the TRAPPIST-1 Planets
• On the diversity of magnetic interactions in close-in star-planet systems
• Predicting the Extreme Ultraviolet Radiation Environment of Exoplanets Around Low-Mass Stars: the TRAPPIST-1 System
• A review of possible planetary atmospheres in the TRAPPIST-1 system
• Planet-induced radio emission from the coronae of M dwarfs: the case of Prox Cen and AU Mic
• SPIRou Input Catalog: Activity, Rotation and Magnetic Field of Cool Dwarfs
• Monitoring the radio emission of Proxima Centauri
• Assessing magnetic torques and energy fluxes in close-in star-planet systems
• Direct and Inverse Cascades in the Acceleration Region of the Fast Solar Wind
• Predicting the Extreme Ultraviolet Radiation Environment of Exoplanets Around Low-Mass Stars: GJ 832, GJ 176, GJ 436
• The large-scale magnetic field of Proxima Centauri near activity maximum
• The Effect of Combined Magnetic Geometries on Thermally Driven Winds I: Interaction of Dipolar and Quadrupolar Fields
• Flux ropes and dynamics of the heliospheric current sheet
• Universal Scaling Laws for Solar and Stellar Atmospheric Heating
• Proton and electron temperatures in the solar wind and their correlations with the solar wind speed
• MOVES V. Modelling star-planet magnetic interactions of HD 189733
• Validation of a wave heated 3D MHD coronal-wind model using Polarized Brightness and EUV observations
• Reconstructing the XUV Spectra of Active Sun-like Stars Using Solar Scaling Relations with Magnetic Flux
• Universal Scaling Laws for Solar and Stellar Atmospheric Heating: Catalog of Power-law Index between Solar Activity Proxies and Various Spectral Irradiances
• MHD study of planetary magnetospheric response during extreme solar wind conditions: Earth and exoplanet magnetospheres applications
• MHD study of extreme space weather conditions for exoplanets with Earth-like magnetospheres: On habitability conditions and radio-emission
• Modeling Solar Wind Variations over an 11-yr Cycle with Alfvén Wave Dissipation: a Parameter Study
• MHD simulations of the space weather in Proxima b: Habitability conditions and radio emission
• The high energy spectrum of Proxima Centauri simultaneously observed at X-ray and FUV wavelengths

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• Ohmic heating in the upper atmosphere of hot exoplanets The influence of a time-varying magnetic field
• A post-common-envelope binary with double-peaked Balmer emission lines from TMTS
• Formation and rising phase of a flux rope through data-constrained simulations
• MHD Simulations Preliminarily Predict The Habitability and Radio Emission of TRAPPIST-1e
• Corotating Interaction Regions (CIRs): evolution over a solar lifetime
• Upper Limits on Planet-Induced GHz Radio Emission from Inactive M Dwarfs