Ionisation in atmospheres of Brown Dwarfs and extrasolar planets I The role of electron avalanche

Abstract

Brown Dwarf and extrasolar planet atmospheres form clouds which strongly influence the local chemistry and physics. These clouds are globally neutral obeying dust-gas charge equilibrium which is, on short time scales, inconsistent with the observation of stochastic ionisation events of the solar system planets. We argue that a significant volume of the clouds in Brown Dwarfs and extrasolar planets is susceptible to local discharge events. These are electron avalanches triggered by charged dust grains. Such intra-cloud discharges occur on time scales shorter than the time needed to neutralise the dust grains by collisional processes. An ensemble of discharges is likely to produce enough free charges to suggest a partial and stochastic coupling of the atmosphere to a large-scale magnetic field.

18 pages in referee's style, 5 figures, Acccepted by ApJ

References in corpus (18)

• Detection of atmospheric haze on an extrasolar planet: The 0.55 - 1.05 micron transmission spectrum of HD189733b with the Hubble Space Telescope
• The 0.8-14.5 micron Spectra of Mid-L to Mid-T Dwarfs: Diagnostics of Effective Temperature, Grain Sedimentation, Gas Transport, and Surface Gravity
• Metals in the Exosphere of the Highly Irradiated Planet WASP-12b
• Can TiO Explain Thermal Inversions in the Upper Atmospheres of Irradiated Giant Planets?
• Chromospheric Activity, Rotation, and Rotational Braking in M and L Dwarfs
• A comparison of chemistry and dust cloud formation in ultracool dwarf model atmospheres
• Early UV Ingress in WASP-12b: Measuring Planetary Magnetic Fields
• Review of recent results on streamer discharges and discussion of their relevance for sprites and lightning
• Dust in Brown Dwarfs and Extra-solar Planets I. Chemical composition and spectral appearance of quasi-static cloud layers
• Consistent simulations of substellar atmospheres and non-equilibrium dust-cloud formation
• Exploring the substellar temperature regime down to ~550K
• A Surprising Reversal of Temperatures in the Brown-Dwarf Eclipsing Binary 2MASS J05352184-0546085
• WASP-14b: 7.3 Mj transiting planet in an eccentric orbit
• Deviations from the local field approximation in negative streamer heads
• WASP-10b: a 3M_J, gas-giant planet transiting a late-type K star
• Three-fluid plasmas in star formation II. Momentum transfer rate coefficients
• 3D hybrid computations for streamer discharges and production of run-away electrons
• The low density transiting exoplanet WASP-15b

Cited by in corpus (32)

• Model atmospheres for massive gas giants with thick clouds: Application to the HR 8799 planets and predictions for future detections
• Understanding Trends Associated with Clouds in Irradiated Exoplanets
• BOSS Ultracool Dwarfs I: Colors and Magnetic Activity of M and L dwarfs
• Disk evolution, element abundances and cloud properties of young gas giant planets
• The shocking transit of WASP-12b: Modelling the observed early ingress in the near ultraviolet
• Atmospheres of Brown Dwarfs
• Origin of electron cyclotron maser-induced radio emissions at ultra-cool dwarfs: magnetosphere-ionosphere coupling currents
• Weather on Other Worlds I: Detection of Periodic Variability in the L3 Dwarf DENIS-P J1058.7-1548 with Precise Multi-Wavelength Photometry
• Clouds of Fluffy Aggregates: How They Form in Exoplanetary Atmospheres and Influence Transmission Spectra
• Volume-limited radio survey of ultracool dwarfs
• 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
• A Signature of Chromospheric Activity in Brown Dwarfs Revealed by 2.5-5.0 Micron AKARI Spectra
• Reference study to characterise plasma and magnetic properties of ultra-cool atmospheres
• The Hyperactive L Dwarf 2MASS J13153094-2649513: Continued Emission and a Brown Dwarf Companion
• MOVES IV. Modelling the influence of stellar XUV-flux, cosmic rays, and stellar energetic particles on the atmospheric composition of the hot Jupiter HD 189733b
• The First Millimeter Detection of a Non-Accreting Ultracool Dwarf
• Ionisation in atmospheres of brown dwarfs and extrasolar planets VI: Properties of large-scale discharge events
• Lightning climatology of exoplanets and brown dwarfs guided by Solar System data
• Ionization in Atmospheres of Brown Dwarfs and Extrasolar Planets V: Alfvén Ionization
• Calibrating Ultracool Dwarfs: Optical Template Spectra, Bolometric Corrections, and $\chi$ Values
• Understanding the atmospheric properties and chemical composition of the ultra-hot Jupiter HAT-P-7b: III. Changing ionisation and the emergence of an ionosphere
• Electrostatic activation of prebiotic chemistry in substellar atmospheres
• Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets
• Electron beam induced radio emission from ultracool dwarfs
• Dust cloud lightning in extraterrestrial atmospheres
• Weather on Other Worlds. VI. Optical Spectrophotometry of Luhman 16B Reveals Large-amplitude Variations in the Alkali Lines
• Dust cloud evolution in sub-stellar atmospheres via plasma deposition and plasma sputtering
• Exploring terrestrial lightning parameterisations for exoplanets and brown dwarfs
• Evolution of spheroidal dust in electrically active sub-stellar atmospheres
• Lightning activity on a tidally locked terrestrial exoplanet in storm-resolving simulations for a range of surface pressures
• Electrostatic instability of non-spherical dust in sub-stellar clouds