Stellar Influence on Heavy Ion Escape from Unmagnetized Exoplanets

Abstract

Planetary habitability is in part determined by the atmospheric evolution of a planet; one key component of such evolution is escape of heavy ions to space. Ion loss processes are sensitive to the plasma environment of the planet, dictated by the stellar wind and stellar radiation. These conditions are likely to vary from what we observe in our own solar system when considering a planet in the habitable zone around an M-dwarf. Here we use a hybrid global plasma model to perform a systematic study of the changing plasma environment and ion escape as a function of stellar input conditions, which are designed to mimic those of potentially habitable planets orbiting M-dwarfs. We begin with a nominal case of a solar wind experienced at Mars today, and incrementally modify the interplanetary magnetic field orientation and strength, dynamic pressure, and Extreme Ultraviolet input. We find that both ion loss morphology and overall rates vary significantly, and in cases where the stellar wind pressure was increased, the ion loss began to be diffusion or production limited with roughly half of all produced ions being lost. This limit implies that extreme care must be taken when extrapolating loss processes observed in the solar system to extreme environments.

arXiv commentAccepted to MNRAS. 10 pages, 3 figures, 2 tables

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• Planetary Magnetic Field Control of Ion Escape from Weakly Magnetized Planets
• Atmospheric Escape From TOI-700 d: Venus versus Earth Analogs
• Observing Isotopologue Bands in Terrestrial Exoplanet Atmospheres with the James Webb Space Telescope---Implications for Identifying Past Atmospheric and Ocean Loss
• The Evolution of Earth's Magnetosphere During the Solar Main Sequence
• Numerical quantification of the wind properties of cool main sequence stars
• A Virtual Solar Wind Monitor at Mars with Uncertainty Quantification using Gaussian Processes