ELECTRODYNAMICS ON EXTRASOLAR GIANT PLANETS

Strong ionization on close-in extrasolar giant planets (EGPs) suggests that their atmospheres may be affected by ion drag and resistive heating arising from wind-driven electrodynamics. We show that photoionization dominates over thermal ionization over much of the dayside atmosphere above the 100 m...

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Bibliographic Details
Published in:The Astrophysical journal 2014-11, Vol.796 (1), p.1-16
Main Authors: Koskinen, T T, Yelle, R V, Lavvas, P, Cho, J Y-K
Format: Article
Language:English
Subjects:
ALKALI METALS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CHROMOSPHERE
COLLISIONS
ELECTRODYNAMICS
ELECTRON DENSITY
ELECTRONS
Extrasolar planets
HEATING
IONIZATION
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
PHOTOIONIZATION
Planetary atmospheres
PLANETARY IONOSPHERES
PLANETS
PLASMA
SATELLITES
SOLAR SYSTEM
SUN
Transit
ULTRAVIOLET RADIATION
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Summary:Strong ionization on close-in extrasolar giant planets (EGPs) suggests that their atmospheres may be affected by ion drag and resistive heating arising from wind-driven electrodynamics. We show that photoionization dominates over thermal ionization over much of the dayside atmosphere above the 100 mbar level, creating an upper ionosphere dominated by ionization of H and He and a lower ionosphere dominated by ionization of metals such as Na, K, and Mg. The resulting dayside electron densities on close-in exoplanets are higher than those encountered in any planetary ionosphere of the solar system, and the conductivities are comparable to the chromosphere of the Sun. A combined approach that relies on UV observations of the upper atmosphere, phase curve and Doppler measurements of global dynamics, and visual transit observations to probe the alkali metals can potentially be used to constrain electrodynamics in the future.
ISSN:1538-4357
0004-637X
1538-4357
DOI:10.1088/0004-637X/796/1/16