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See detailOn the origin of the 2-3 minutes quasi-periodicity in the Jovian magnetosphere
Bonfond, Bertrand ULg; Vogt, Marissa F.; Gérard, Jean-Claude ULg et al

Poster (2011, October 05)

Several kinds of periodicities have been observed at Jupiter since the first probes fly-by. However, pre- vious investigations mainly focused on the longer timescales, such as the 40 minutes (QP40) or the ... [more ▼]

Several kinds of periodicities have been observed at Jupiter since the first probes fly-by. However, pre- vious investigations mainly focused on the longer timescales, such as the 40 minutes (QP40) or the 2- 3 days quasi-periodicity. Here we describe the recent finding of the 2-3 minutes quasi-periodic occurrence of UV flares in the active region of the polar aurora. These observations are then compared to other measurements of such quasi-periodic behaviors in electron and magnetic field data and their probably common origin is discussed. [less ▲]

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See detailImproved mapping of Jupiter’s auroral features to magnetospheric sources
Vogt, Marissa. F.; Kivelson, Margaret. G.; Khurana, Krishan. K. et al

in Journal of Geophysical Research. Space Physics (2011), 116

The magnetospheric mapping of Jupiter's polar auroral emissions is highly uncertain because global Jovian field models are known to be inaccurate beyond ∼30 RJ. Furthermore, the boundary between open and ... [more ▼]

The magnetospheric mapping of Jupiter's polar auroral emissions is highly uncertain because global Jovian field models are known to be inaccurate beyond ∼30 RJ. Furthermore, the boundary between open and closed flux in the ionosphere is not well defined because, unlike the Earth, the main auroral oval emissions at Jupiter are likely associated with the breakdown of plasma corotation and not the open/closed flux boundary in the polar cap. We have mapped contours of constant radial distance from the magnetic equator to the ionosphere in order to understand how auroral features relate to magnetospheric sources. Instead of following model field lines, we map equatorial regions to the ionosphere by requiring that the magnetic flux in some specified region at the equator equals the magnetic flux in the area to which it maps in the ionosphere. Equating the fluxes in this way allows us to link a given position in the magnetosphere to a position in the ionosphere. We find that the polar auroral active region maps to field lines beyond the dayside magnetopause that can be interpreted as Jupiter's polar cusp; the swirl region maps to lobe field lines on the night side and can be interpreted as Jupiter's polar cap; the dark region spans both open and closed field lines and must be explained by multiple processes. Additionally, we conclude that the flux through most of the area inside the main oval matches the magnetic flux contained in the magnetotail lobes and is probably open to the solar wind. [less ▲]

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See detailRelating Jupiter's auroral features to magnetospheric sources
Vogt, Marissa F.; Kivelson, Margaret G.; Khurana, Krishan K. et al

Poster (2010, December)

In order to understand the physical processes that produce the various auroral features we must first understand how the auroral emissions are linked to magnetospheric sources. However, magnetic mapping ... [more ▼]

In order to understand the physical processes that produce the various auroral features we must first understand how the auroral emissions are linked to magnetospheric sources. However, magnetic mapping of Jupiter’s polar auroral emissions to equatorial regions in which source currents are plausibly generated is highly uncertain because the available field models are inaccurate beyond ~30 Jovian radii. We have related auroral features to their magnetospheric sources through a flux equivalence calculation, where we require that the magnetic flux in some specified region at the equator equals the magnetic flux in the area to which it links in the ionosphere. This approach is preferred to tracing model field lines for mapping the auroral polar regions, because the latter method is inaccurate at large distances. Here we present our results, highlighting new mappings for the southern hemisphere, and will compare our mapping to auroral observations from both hemispheres. In particular we relate equatorial regions in which reconnection events have been identified with the locations of polar dawn spots and other possible auroral signatures of tail reconnection. We find that the mapping reproduces several other key auroral features. The polar auroral active region maps to just outside the dayside magnetopause, a region that we identify as the Jovian polar cusp. The polar auroral swirl region maps to open tail field lines and is interpreted as the Jovian polar cap. These interpretations are consistent with some earlier predictions based on auroral observations. We identify the boundary between open and closed flux in the ionosphere, which previously was not well defined. We show that the magnetic flux through the regions interpreted as the polar caps in both hemispheres closely matches the estimated flux through the tail lobe, consistent with the suggestion that this area maps to open field lines. [less ▲]

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