First Vertical Ion Density Profile in Jupiter’s Auroral Atmosphere: Direct Observations Using the Keck II Telescope

Lystrup, Makenzie; Miller, Steve; Russo, N. Dello; Vervack, R. J.; Stallard, T.

doi:10.1086/529509

Cited by 45 publications

(63 citation statements)

References 34 publications

(50 reference statements)

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“…This justification also applies to Jupiter. Vertical profiles of electron density are available, from radio occultation data (Hinson et al, 1997(Hinson et al, , 1998) and more recently from telescopic observations (Lystrup et al, 2008). However, these profiles are spatially scattered and are not co-located with measurements of vertical thermospheric structure that would permit reliable calculations of ionospheric conductivity.…”

Section: Ionosphere Modelmentioning

confidence: 99%

Coupled rotational dynamics of Jupiter's thermosphere and magnetosphere

2009

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Abstract.We describe an axisymmetric model of the coupled rotational dynamics of the thermosphere and magnetosphere of Jupiter that incorporates self-consistent physical descriptions of angular momentum transfer in both systems. The thermospheric component of the model is a numerical general circulation model. The middle magnetosphere is described by a simple physical model of angular momentum transfer that incorporates self-consistently the effects of variations in the ionospheric conductivity. The outer magnetosphere is described by a model that assumes the existence of a Dungey cycle type interaction with the solar wind, producing at the planet a largely stagnant plasma flow poleward of the main auroral oval. We neglect any decoupling between the plasma flows in the magnetosphere and ionosphere due to the formation of parallel electric fields in the magnetosphere. The model shows that the principle mechanism by which angular momentum is supplied to the polar thermosphere is meridional advection and that mean-field Joule heating and ion drag at high latitudes are not responsible for the high thermospheric temperatures at low latitudes on Jupiter. The rotational dynamics of the magnetosphere at radial distances beyond ∼30 R J in the equatorial plane are qualitatively unaffected by including the detailed dynamics of the thermosphere, but within this radial distance the rotation of the magnetosphere is very sensitive to the rotation velocity of the thermosphere and the value of the Pedersen conductivity. In particular, the thermosphere connected to the inner magnetosphere is found to super-corotate, such that true Pedersen conductivities smaller than previously predicted are required to enforce the observed rotation of the magnetosphere within ∼30 R J . We find that increasing the Joule heating at high latitudes by adding a component due to rapidly fluctuating electric fields is unable to explain the Correspondence to: C. G. A. Smith (cgasmith@gmail.com) high equatorial temperatures. Adding a component of Joule heating due to fluctuations at low latitudes is able to explain the high equatorial temperatures, but the thermospheric wind systems generated by this heating cause super-corotation of the inner magnetosphere in contradiction to the observations. We conclude that the coupled model is a particularly useful tool for study of the thermosphere as it allows us to constrain the plausibility of predicted thermospheric structures using existing observations of the magnetosphere.

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Section: Ionosphere Modelmentioning

confidence: 99%

Coupled rotational dynamics of Jupiter's thermosphere and magnetosphere

2009

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“…They observed several lines, in particular the strong emission lines at 2.095 and 2.105 lm, using the Fourier Transform Spectrometer (FTS) (Maillard and Michel, 1982) at CFHT. Many other lines have since been observed (e.g., Oka and Geballe, 1990;Maillard et al, 1990;Kim et al, 1991b;Drossart et al, 1993;Stallard et al, 2001;Raynaud et al, 2004;Lystrup et al, 2008). These emission lines have been used to derive temperatures and H þ 3 abundances in the upper atmosphere of Jupiter (e.g., Stallard et al, 2002;Raynaud et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Spectro-imaging observations of Jupiter’s 2μm auroral emission. II: Thermospheric winds

Chaufray

Greathouse

Gladstone

et al. 2011

Icarus

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“…The first (top) image and the second (immediately below) show the full southern auroral oval, displayed on the disk of the planet. The oval is strongly limb-brightened on the dusk limb due to both the oval coinciding with the limb and the fact that H + 3 extends up to high altitudes, some 3000 km or more above the reference 1 bar level (Lystrup et al 2008). Thus our line-of-sight passes through an extended column of H + 3 .…”

Section: Observationsmentioning

confidence: 99%

Is the Jovian auroral H\hbox{$_{3}^{+}$} emission polarised?

Barthélemy

Lystrup

Menager

et al. 2011

A&A

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Context. Measurement of linear polarisation in Earth's thermospheric oxygen red line can be a useful observable quantity for characterising conditions in the upper atmosphere; therefore, polarimetry measurements are extended to other planets. Since FUV emissions are not observable from the ground, the best candidates for Jupiter auroral emissions are H + 3 infrared lines near 4 μm. This ion is created after a chemical process in the Jovian upper atmosphere. Thus the anisotropy responsible of the polarisation cannot be the particle impact as in the Earth case. Aims. The goal of this study is to detect polarisation of H + 3 emissions from Jupiter's aurora. Methods. Measurements of the H + 3 emissions from Jupiter's southern auroral oval were performed at the UK Infrared Telescope using the UIST-IRPOL spectro-polarimeter, with the instrument slit positioned perpendicular to Jupiter's rotation axis. Data were processed by dividing the slit into 24 bins. Stokes parameters (u, q and v), polarisation degree and direction were extracted for each bin and debiased. Results. More than 5 bins show polarisation with a confidence level above 3σ. Polarisation degrees up to 7% are detected. Assuming the auroral intensity is constant during the 8 waveplate positions exposure time, i.e. around 10 min, strong circular polarisation is present, with an absolute value of the Stokes v parameter up to 0.35. Conclusions. This study shows that polarisation is detectable in the Jovian infrared auroras, but new measurements are needed to be able to use it to characterise the ionospheric environment. At present, it is not possible to propose a mechanism to explain this polarisation owing to the lack of theoretical work and laboratory experiments concerning the polarisation of H + 3 .

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First Vertical Ion Density Profile in Jupiter’s Auroral Atmosphere: Direct Observations Using the Keck II Telescope

Cited by 45 publications

References 34 publications

Coupled rotational dynamics of Jupiter's thermosphere and magnetosphere

Coupled rotational dynamics of Jupiter's thermosphere and magnetosphere

Spectro-imaging observations of Jupiter’s 2μm auroral emission. II: Thermospheric winds

Is the Jovian auroral H\hbox{$_{3}^{+}$} emission polarised?

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