Exoplanets as probes of the winds of host stars: the case of the M dwarf GJ 436

Abstract

Winds of cool dwarfs are difficult to observe, with only a few M dwarfs presenting observationally-derived mass-loss rates (Mdot), which span several orders of magnitude. Close-in exoplanets are conveniently positioned in the inner regions of stellar winds and can, thus, be used to probe the otherwise-unobservable local properties of their host-stars' winds. Here, we use local stellar wind characteristics observationally-derived in the studies of atmospheric evaporation of the warm-neptune GJ436 b to derive the global characteristics of the wind of its M-dwarf host. Using an isothermal wind model, we constrain the stellar wind temperature to be in the range [0.36,0.43] MK, with Mdot=[0.5,2.5] x 10^{-15} Msyn/yr. By computing the pressure balance between the stellar wind and the interstellar medium, we derive the size of the astrophere of GJ436 to be around 25 au, significantly more compact than the heliosphere. We demonstrate in this paper that transmission spectroscopy, coupled to planetary atmospheric evaporation and stellar wind models, can be a useful tool for constraining the large-scale wind structure of planet-hosting stars. Extending our approach to future planetary systems discoveries will open new perspectives for the combined characterisation of planetary exospheres and winds of cool dwarf stars.

MNRAS in press

References in corpus (17)

• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b
• Stellar magnetism: empirical trends with age and rotation
• The Structure of the Local Interstellar Medium V: Electron Densities
• A Re-appraisal of the Habitability of Planets Around M Dwarf Stars
• Lyman-$\alpha$ Transit Spectroscopy and the Neutral Hydrogen Tail of the Hot Neptune GJ436b
• Early UV Ingress in WASP-12b: Measuring Planetary Magnetic Fields
• Energetic neutral atoms as the explanation for the high velocity hydrogen around HD 209458b
• Magnetic moment and plasma environment of HD 209458b as determined from Ly$\alpha$ observations
• A global analysis of Spitzer and new HARPS data confirms the loneliness and metal-richness of GJ 436 b
• The transiting exoplanet host star GJ 436: a test of stellar evolution models in the lower main sequence, and revised planetary parameters
• The effects of stellar winds on the magnetospheres and potential habitability of exoplanets
• Powerful Winds from Low-Mass Stars: V374 Peg
• Modeling magnesium escape from HD209458b atmosphere
• Radio emission and mass loss rate limits of four young solar-type stars
• First Detection of Thermal Radio Emission from Solar-Type Stars with the Karl G. Jansky Very Large Array
• On the magnetic structure and wind parameter profiles of Alfven wave driven winds in late-type supergiant stars

Cited by in corpus (32)

• Hubble PanCET: An extended upper atmosphere of neutral hydrogen around the warm Neptune GJ 3470 b
• New Observational Constraints on the Winds of M Dwarf Stars
• The evolution of the solar wind
• Investigating the young AU~Mic system with SPIRou: large-scale stellar magnetic field and close-in planet mass
• Stellar Coronal Mass Ejections I. Estimating occurrence frequencies and mass-loss rates
• Stellar wind effects on the atmospheres of close-in giants: a possible reduction in escape instead of increased erosion
• Do non-dipolar magnetic fields contribute to spin-down torques?
• MOVES II. Tuning in to the radio environment of HD189733b
• GJ 436b and the stellar wind interaction: simulations constraints using Ly$\alpha$ and H$\alpha$ transits
• The solar wind from a stellar perspective: how do low-resolution data impact the determination of wind properties?
• Stellar versus Galactic: The intensity of cosmic rays at the evolving Earth and young exoplanets around Sun-like stars
• Possible Atmospheric Diversity of Low Mass Exoplanets, some Central Aspects
• Can we detect aurora in exoplanets orbiting M dwarfs?
• From Stellar Coronæ to Gyrochronology: a theoretical and observational exploration
• The space weather around the exoplanet GJ 436 b. II. Stellar wind-exoplanet interactions
• The space weather around the exoplanet GJ 436b
• Transit Ly-$\alpha$ signatures of terrestrial planets in the habitable zones of M dwarfs
• The Earth-like Galactic cosmic ray intensity in the habitable zone of the M dwarf GJ 436
• Global trends in winds of M dwarf stars
• M-dwarf's Chromosphere, Corona and Wind Connection via the Nonlinear Alfvén Wave
• Breezing through the space environment of Barnard's Star b
• Numerical quantification of the wind properties of cool main sequence stars
• X-ray detection of astrospheres around three main-sequence stars and their mass-loss rates
• Star-Planet Interactions: A Computational View
• A Study of the Magnetic Activity and Variability of GJ 436
• Accounting for Differential Rotation in Calculations of the Sun's Angular Momentum-loss Rate
• Nonlinear Alfvén Wave Model of Stellar Coronae and Winds from the Sun to M dwarfs
• Radio eclipses of exoplanets by the winds of their host stars
• Galactic cosmic ray propagation through M dwarf planetary systems
• sunset: A database of synthetic atmospheric-escape transmission spectra for nearly every transiting planet
• Modeling the astrosphere of LHS~1140
• The impact of stellar winds and tidal locking effects on the habitability of Earth-like exoplanets around M dwarf stars