Auroral Processes at the Giant Planets: Energy Deposition, Emission Mechanisms, Morphology and Spectra (original) (raw)
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Journal of Geophysical Research, 2011
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Journal of Geophysical Research, 2008
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Magnetized plasmas in motion inevitably generate currents and the magnetized plasmas that form the magnetospheres of the outer planets are no exception. Although a focus on the current systems tends to distract from the underlying dynamics, many elements of magnetospheric structure can be organized by discussing them in terms of the large scale currents present in the system. This paper starts with a digression on the pitfalls of a current-based description of a planetary magnetosphere but then proceeds to characterize the magnetospheres of Jupiter, Earth, and to some extent Saturn by the currents that flow within them. Emphasis is placed on the field-aligned currents that couple the equatorial magnetospheres to the ionospheres and the conditions that call for the development of field-aligned electric fields.
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The Astrophysical Journal, 2012
Weak intrinsic magnetic dipole moments of tidally locked close-in giant exoplanets ("hot Jupiters") have been shown in previous studies to be unable to provide an efficient magnetospheric protection for their expanding upper atmospheres against the stellar plasma flow, which should lead to significant non-thermal atmosphere mass loss. The present work provides a more complete view of the magnetosphere structure of "hot Jupiters," based on a paraboloid magnetospheric model (PMM). Besides the intrinsic planetary magnetic dipole, the PMM considers among the main magnetic field sources also the electric current system of the magnetotail, magnetopause currents, and the ring current of a magnetodisk. Due to the outflow of ionized particles from the hydrodynamically expanding upper atmosphere, "hot Jupiters" may have extended magnetodisks. The magnetic field produced by magnetodisk ring currents dominates above the contribution of an intrinsic magnetic dipole of a "hot Jupiter" and finally determines the size and shape of the whole magnetosphere. A slower-than-the-dipole-type decrease of the magnetic field with the distance forms the essential specifics of magnetodisk-dominated magnetospheres of "hot Jupiters." This results in their 40%-70% larger scales compared to those traditionally estimated by only the planetary dipole taken into account. Therefore, the formation of magnetodisks has to be included in the studies of the stellar wind plasma interaction with close-in exoplanets, as well as magnetospheric protection for planetary atmospheres against non-thermal escape due to erosion by the stellar plasma flow.