A self‐consistent model of the Jovian auroral thermal structure

Grodent, Denis; Waite, J. H.; Gérard, Jean‐Claude

doi:10.1029/2000ja900129

Cited by 184 publications

(422 citation statements)

References 96 publications

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“…However, this hypothesis was later questioned because the electron beams were found unable to carry enough power to generate the observed IFP, given the assumed extent of the beams close to Io [Mauk et , we find that the energy flux contained in the electron beams can deliver 30 mW/m 2 into Jupiter's ionosphere.The leading spot size on the images is approximately 350 Â 150 km 2 , so that the total power reaches $1.6 GW. Assuming a $15% efficiency [Grodent et al, 2001], the injected power leads to $0.24 GW emitted power, on the same order but somewhat smaller than typical values of 0.7 GW for the leading spot. Since the beams have been observed in the center of Io's wake and during polar flybys, the current system might be more complex than illustrated in Figure 4.…”

Section: Interpretation and Discussionmentioning

confidence: 89%

UV Io footprint leading spot: A key feature for understanding the UV Io footprint multiplicity?

Bonfond

Grodent

Gérard

et al. 2008

Geophysical Research Letters

140

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The electromagnetic interaction between Io and the Jovian magnetosphere generates a UV auroral footprint in both Jovian hemispheres. Multiple spots were observed in the northern Jovian hemisphere when Io was in the northern part of the plasma torus and vice‐versa for the South. Based on recent Hubble Space Telescope (HST) measurements, we report here the discovery of a UV leading spot, i.e., a faint emission located ahead of the main spot. The leading spot emerges at System III longitudes between 0° and 100° in the northern hemisphere and between 130° and 300° in the southern hemisphere, i.e., in one hemisphere when multiple spots are observed in the other hemisphere. We propose as one potential mechanism that electron beams observed near Io are related to the generation of the leading spot and the secondary spot in the opposite hemisphere.

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Section: Interpretation and Discussionmentioning

confidence: 89%

UV Io footprint leading spot: A key feature for understanding the UV Io footprint multiplicity?

Bonfond

Grodent

Gérard

et al. 2008

Geophysical Research Letters

140

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“…As for the lower boundary condition, we adopt Jovian auroral mixing ratios (Grodent et al 2001) for models with a = 0.2-1 AU, while for a < 0.2 AU we use the mixing ratio of H from Liang et al (2003). We assume the planets to be tidally synchronized if the orbital distance is between 0.047 and 0.2 AU and to be rotating asynchronously with a period of 10 hr beyond 0.2 AU.…”

Section: Methodsmentioning

confidence: 99%

Ionization of Extrasolar Giant Planet Atmospheres

Koskinen

Cho

Achilleos

et al. 2010

ApJ

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Many extrasolar planets orbit close in and are subject to intense ionizing radiation from their host stars. Therefore, we expect them to have strong, and extended, ionospheres. Ionospheres are important because they modulate escape in the upper atmosphere and can modify circulation, as well as leave their signatures, in the lower atmosphere. In this paper, we evaluate the vertical location Z I and extent D I of the EUV ionization peak layer. We find that Z I ≈ 1-10 nbar-for a wide range of orbital distances (a = 0.047-1 AU) from the host star-and D I /H p 15, where H p is the pressure scale height. At Z I , the plasma frequency is ∼80-450 MHz, depending on a. We also study global ion transport, and its dependence on a, using a three-dimensional thermosphere-ionosphere model. On tidally synchronized planets with weak intrinsic magnetic fields, our model shows only a small, but discernible, difference in electron density from the dayside to the nightside (∼9 × 10 13 m −3 to ∼2 × 10 12 m −3 , respectively) at Z I . On asynchronous planets, the distribution is essentially uniform. These results have consequences for hydrodynamic modeling of the atmospheres of close-in extrasolar giant planets.

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“…Higher power densities are possible with the electric current generation mechanism. Models of interaction between electrons and Jupiter's atmosphere 22 , recalculated with the energy distribution shapes measured in Fig. 2, yield about 3 erg cm -2 s -1 for the electron input needed to explain the auroral emissions.…”

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confidence: 99%

“…23). Atmospheric penetration of electrons modelled for diffuse aurorae require the involvement of over 48 keV electrons to explain even the peak auroral emissions 24,22 . M…”

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confidence: 99%