Lightning and charge processes in brown dwarf and exoplanet atmospheres

Abstract

The study of the composition of brown dwarf atmospheres helped to understand their formation and evolution. Similarly, the study of exoplanet atmospheres is expected to constrain their formation and evolutionary states. We use results from 3D simulations, kinetic cloud formation and kinetic ion-neutral chemistry to investigate ionisation processes which will affect their atmosphere chemistry: The dayside of super-hot Jupiters is dominated by atomic hydrogen, and not H${}_2$O. Such planetary atmospheres exhibit a substantial degree of thermal ionisation and clouds only form on the nightside where lightning leaves chemical tracers (e.g. HCN) for possibly long enough to be detectable. External radiation may cause exoplanets to be enshrouded in a shell of highly ionised, H${}_3^{+}$-forming gas and a weather-driven aurora may emerge. Brown dwarfs enable us to study the role of electron beams for the emergence of an extrasolar, weather-system driven aurora-like chemistry, and the effect of strong magnetic fields on cold atmospheric gases. Electron beams trigger the formation of H${}_3^{+}$ in the upper atmosphere of a brown dwarf (e.g. LSR-J1835) which may react with it to form hydronium, H${}_3$O${}^{+}$, as a longer lived chemical tracer. Brown dwarfs and super-hot gas giants may be excellent candidates to search for H${}_3$O${}^{+}$ as an H${}_3^{+}$ product.

arXiv comment16 pages, accepted for publication in the Philosophical Transactions A of the Royal Society, (some typos corrected)

References in corpus (60)

• Models of Stars, Brown Dwarfs and Exoplanets
• A map of the day-night contrast of the extrasolar planet HD 189733b
• Hubble Space Telescope Transmission Spectroscopy of the Exoplanet HD 189733b: High-altitude atmospheric haze in the optical and near-UV with STIS
• Cosmic-ray ionization of molecular clouds
• From thermal dissociation to condensation in the atmospheres of ultra hot Jupiters: WASP-121b in context
• Masses, Radii, and Cloud Properties of the HR 8799 Planets
• Atomic iron and titanium in the atmosphere of the exoplanet KELT-9b
• Exploring Exoplanet Populations with NASA's Kepler Mission
• Confirmation of the Electron Cyclotron Maser Instability as the Dominant Source of Radio Emission from Very Low Mass Stars and Brown Dwarfs
• HST Spectral Mapping of L/T Transition Brown Dwarfs Reveals Cloud Thickness Variations
• Global Climate and Atmospheric Composition of the Ultra-Hot Jupiter WASP-103b from HST and Spitzer Phase Curve Observations
• VULCAN: an Open-Source, Validated Chemical Kinetics Python Code for Exoplanetary Atmospheres
• Large Amplitude Variations of an L/T Transition Brown Dwarf: Multi-Wavelength Observations of Patchy, High-Contrast Cloud Features
• Search for Carbon Monoxide in the atmosphere of the Transiting Exoplanet HD189733b
• Spatially resolved eastward winds and rotation of HD 189733b
• A self-consistent cloud model for brown dwarfs and young giant exoplanets: comparison with photometric and spectroscopic observations
• Flaring Up All Over -- Radio Activity in Rapidly-Rotating Late-Type M and L Dwarfs
• Dynamic mineral clouds on HD 189733b I. 3D RHD with kinetic, non-equilibrium cloud formation
• Magnetospherically driven optical and radio aurorae at the end of the stellar main sequence
• An absolute sodium abundance for a cloud-free 'hot Saturn' exoplanet
• L-dwarf variability: I-band observations
• Three Dimensional Radiative Hydrodynamical Simulations of the Highly Irradiated Short Period Exoplanet HD189733b
• The Peculiar Atmospheric Chemistry of KELT-9b
• A Chemical Kinetics Network for Lightning and Life in Planetary Atmospheres
• Exoplanet atmospheres with GIANO. I. Water in the transmission spectrum of HD 189733b
• Hydrogen Cyanide in Nitrogen-Rich Atmospheres of Rocky Exoplanets
• Simulating the cloudy atmospheres of HD 209458 b and HD 189733 b with the 3D Met Office Unified Model
• The Strongest Magnetic Fields on the Coolest Brown Dwarfs
• Characterizing the thermosphere of HD209458b with UV transit observations
• The mineral clouds on HD 209458b and HD189733b
• Spherically symmetric model atmospheres for low mass pre-Main Sequence stars with effective temperatures between 2000 and 6800 K
• Effects of Bulk Composition on The Atmospheric Dynamics on Close-in Exoplanets
• Atmospheric Circulation of Brown Dwarfs and Jupiter and Saturn-like Planets: Zonal Jets, Long-term Variability, and QBO-type Oscillations
• Hint of 150 MHz radio emission from the Neptune-mass extrasolar transiting planet HAT-P-11b
• Origin of electron cyclotron maser-induced radio emissions at ultra-cool dwarfs: magnetosphere-ionosphere coupling currents
• Modelling the local and global cloud formation on HD 189733b
• Sparkling nights and very hot days on WASP-18b: the formation of clouds and the emergence of an ionosphere
• Observing a column-dependent zeta in dense interstellar sources: the case of the Horsehead Nebula
• Connecting the dots: A versatile model for the atmospheres of tidally locked Super-Earths
• A Search for Variability in Exoplanet Analogues and Low-Gravity Brown Dwarfs
• ExoMol molecular line lists XX: a comprehensive line list for H${}_3^{+}$
• Ionisation in atmospheres of Brown Dwarfs and extrasolar planets III. Breakdown conditions for mineral clouds
• Multiwaveband photometry of the irradiated brown dwarf WD0137-349B
• Ionisation in atmospheres of Brown Dwarfs and extrasolar planets II Dust-induced collisional ionization
• Ionization in atmospheres of Brown Dwarfs and extrasolar planets IV. The Effect of Cosmic Rays
• Reference study to characterise plasma and magnetic properties of ultra-cool atmospheres
• Lightning Chemistry on Earth-like Exoplanets
• A chemical kinetics code for modelling exoplanetary atmospheres
• Emission lines in the atmosphere of the irradiated brown dwarf WD0137-349B
• Lightning climatology of exoplanets and brown dwarfs guided by Solar System data
• The Influence of Galactic Cosmic Rays on Ion-Neutral Hydrocarbon Chemistry in the Upper Atmospheres of Free-Floating Exoplanets
• EUV-driven ionospheres and electron transport on extrasolar giant planets orbiting active stars
• The direct detection of the irradiated brown dwarf in the white dwarf - brown dwarf binary SDSS J141126.20+200911.1
• No Detectable H3+ Emission from the Atmospheres of Hot Jupiters
• Is lightning a possible source of the radio emission on HAT-P-11b?
• Search for H3+ in HD141569A
• Atmospheric electrification in dusty, reactive gases in the solar system and beyond
• Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets
• A CRIRES-search for H3+ emission from the hot Jupiter atmosphere of HD 209458 b
• Exo-lightning radio emission: the case study of HAT-P-11b

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• Patchy Forsterite Clouds in the Atmospheres of Two Highly Variable Exoplanet Analogs
• From cold to hot irradiated gaseous exoplanets: Fingerprints of chemical disequilibrium in atmospheric spectra
• Grid of pseudo-2D chemistry models for tidally locked exoplanets -- II. The role of photochemistry
• The Galactic cosmic ray intensity at the evolving Earth and young exoplanets
• Stellar versus Galactic: The intensity of cosmic rays at the evolving Earth and young exoplanets around Sun-like stars
• Understanding the atmospheric properties and chemical composition of the ultra-hot Jupiter HAT-P-7b II. Mapping the effects of gas kinetics
• ExoMol line lists -- XL. Ro-vibrational molecular line list for the hydronium ion (H${}_3$O${}^{+}$)
• Ions in the Thermosphere of Exoplanets: Observable Constraints Revealed by Innovative Laboratory Experiments
• Limits on the Auroral Generation of H${}_3^{+}$ in Brown Dwarf and Extrasolar Giant Planet Atmospheres with Keck/NIRSPEC
• The energetic particle environment of a GJ 436 b-like planet
• Charting nearby stellar systems: The intensity of Galactic cosmic rays for a sample of solar-type stars
• The strong suppression of Galactic cosmic rays reaching AU Mic b, c and Prox Cen b