References of "Paranicas, Chris"
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See detailThe polar region of Jupiter’s aurora : barcode noise, conjugate flares and more...
Bonfond, Bertrand ULiege; Grodent, Denis ULiege; Gladstone, Randy et al

Conference (2018, July 11)

Juno’s unprecedented polar orbits around Jupiter allow for unique observations of the polar aurorae and related phenomena. Here we make use of Juno-UVS, the UV imaging spectrograph operating in the 60-200 ... [more ▼]

Juno’s unprecedented polar orbits around Jupiter allow for unique observations of the polar aurorae and related phenomena. Here we make use of Juno-UVS, the UV imaging spectrograph operating in the 60-200 nm range, to explore the polar physics in two very different ways. In the first part of this presentation, we will analyze the rapid variations of the background noise caused by >10MeV electrons penetrating the instrument. In UV images, this rapidly varying signal takes the form of a barcode-like pattern. We will discuss the mapping, the altitude and the characteristic timescale of the “barcode events” in order to constrain the mechanisms giving rise to them. In the second part, we will compare simultaneous observations of the aurorae from the two hemispheres. One dataset comes from Juno-UVS while the other comes from the Hubble Space Telescope STIS instrument. We will show that most auroral features in one hemisphere have a clear counterpart in the other one. Among other examples, we will show evidence of conjugate flares in the active region of the two hemispheres. However, other strong brightness enhancements only show up in one hemisphere, without any echo in the other one. [less ▲]

Detailed reference viewed: 45 (6 ULiège)
See detailA comparative examination of auroral acceleration processes at Jupiter and Earth as enabled by the Juno mission to Jupiter
Mauk, Barry; Haggerty, Dennis; Paranicas, Chris et al

Conference (2017, December 12)

Particle distributions observed by Juno’s Energetic Particle Detector Investigation (JEDI) at low altitudes over Jupiter’s polar regions are exceedingly diverse in directionality and in the shapes of ... [more ▼]

Particle distributions observed by Juno’s Energetic Particle Detector Investigation (JEDI) at low altitudes over Jupiter’s polar regions are exceedingly diverse in directionality and in the shapes of their 3-dimensional energy distributions. Asymmetric, bi-directional angular beams with broad energy distributions are often observed near Jupiter’s main auroral oval with considerable variability as to whether upward or downward intensities are the strongest. Signatures of upward and downward magnetic field-aligned potentials, with inferred potentials up to 100’s of kV are sometimes observed, but unlike at Earth, these potentials do not seem to be associated with the strongest discrete-like auroral emission intensities. Particle distributions have similarities to those observed at Earth over the various phenomenological auroral emission regions, but they are observed in unexpected places with respect to the strongest auroral emission regions, and the jovian distributions are much more energetic. We present a comparative examination of auroral acceleration processes observed at Earth and Jupiter in relation to the respective auroral emission regions. [less ▲]

Detailed reference viewed: 32 (1 ULiège)
See detailSolar wind interaction, structure, and dynamics of the outer planet magnetospheres: A report on the ongoing activities of two ISSI teams
Vogt, Marissa; Jackman, Caitriona; Masters, Adam et al

Poster (2017, June 15)

In 2015 two teams of scientists were selected by the International Space Science Institute (ISSI) in Bern with similar goals of understanding the nature of the solar wind interaction with the ... [more ▼]

In 2015 two teams of scientists were selected by the International Space Science Institute (ISSI) in Bern with similar goals of understanding the nature of the solar wind interaction with the magnetospheres of Jupiter and Saturn and the resulting structure and dynamics of the magnetospheric boundary regions. The team “How does the Solar Wind Influence the Giant Planet Magnetospheres?” is led by Marissa Vogt and Adam Masters and the team “Structure and Dynamics of Jupiter’s Magnetosphere and Boundary Regions” is led by Caitriona Jackman and Chris Paranicas. Because these two teams share several overlapping scientific goals the teams decided to combine activities and hold a joint first meeting, which occurred in April 2016. The second team meeting will also be a joint meeting of the two teams and will be held in September 2017. Some of the outstanding research questions that the teams have been addressing include: “How do processes like magnetic reconnection and the viscous interaction at the Jovian and Saturnian magnetopauses compare to the same processes at Earth’s magnetopause?” and “Is there evidence that the solar wind drives tail reconnection at Jupiter and Saturn? If so, what process (dayside reconnection, solar wind compression) is responsible?” Here we report on some of the initial team activities, which include data analysis, modeling, and theory. Additionally, we will take this opportunity to solicit input from the wider MOP community before the second team meeting. [less ▲]

Detailed reference viewed: 42 (1 ULiège)
See detailParticle energization and structuring of Jupiter’s main auroral oval as diagnosed with Juno measurements of (>30 keV) energetic particles
Mauk, Barry; Haggerty, Dennis; Paranicas, Chris et al

Conference (2017, June 14)

Juno polar low-altitude energetic particle observations indicate that the most intense emissions from Jupiter’s main auroral oval are caused by the impingement onto the atmosphere of relatively flat ... [more ▼]

Juno polar low-altitude energetic particle observations indicate that the most intense emissions from Jupiter’s main auroral oval are caused by the impingement onto the atmosphere of relatively flat, energy-monotonic electron distributions, often extending to energies >1 MeV. They can be associated with bi-directional angular beaming with upward fluxes greater than the downward fluxes. Downward fluxes of >800 mW/m^2 have been observed. However, when viewed in high time resolution ( 1.0s) these distributions are sometimes (3 of 8)) intermixed with >50keV downward accelerated electron distributions with the classic inverted-V configuration, indicative of steady magnetic field-aligned electric fields. The highest downward energy peak observed so far is 400 keV. The inverted-V energy distributions lack the high energy tails observed in adjacent regions, and thus, contrary to what is observed at Earth, the associated downward energy fluxes are generally lower than the downward energy fluxes associated with the more intense energy-monotonic distributions. The relationship between these two modes of auroral particle energization is unclear. Do the classic auroral processes that create inverted-V distributions become so powerful that instabilities are stimulated that cause stochastic energization to turn on and dominate, or do these two different forms of auroral acceleration represent distinctly different processes? These and other questions are explored. [less ▲]

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See detailSimulations of the auroral signatures of Jupiter’s magnetospheric injections
Dumont, Maïté ULiege; Grodent, Denis ULiege; Radioti, Aikaterini ULiege et al

Conference (2015, September 29)

We report the evolution of ultraviolet auroral features located equatorward of the main emission appearing in the Hubble Space Telescope (HST) images of the northern and the southern Jovian hemisphere. We ... [more ▼]

We report the evolution of ultraviolet auroral features located equatorward of the main emission appearing in the Hubble Space Telescope (HST) images of the northern and the southern Jovian hemisphere. We investigate the possibility that those ultraviolet auroral structures are associated with energetic particle injections. For this study, we compare the characteristics of the simulated auroral signature of plasma injections with the observed parameters of equatorward isolated auroral structures. [less ▲]

Detailed reference viewed: 22 (6 ULiège)
See detailSimulations of the auroral signatures of Jupiter’s magnetospheric injections
Dumont, Maïté ULiege; Grodent, Denis ULiege; Radioti, Aikaterini ULiege et al

Poster (2015, June 04)

Jupiter’s ultraviolet auroral emissions are divided into four main components: the polar emissions, the main emission, the satellite footprints and the outer emissions. The morphology of the outer ... [more ▼]

Jupiter’s ultraviolet auroral emissions are divided into four main components: the polar emissions, the main emission, the satellite footprints and the outer emissions. The morphology of the outer emissions can be either diffuse, arc-shaped or compact emissions. In the present study, we focus on outer emissions clearly detaching from the main emission and forming compact structures that are evolving regardless of the rest of the auroral emission. These auroral features were selected because they have the same appearance as the auroral signature of a clearly identified injection previously observed by Mauk et al. [2002] at Jupiter, based on simultaneous Galileo spacecraft and Hubble Space Telescope measurements. Here, we report on the evolution of those ultraviolet auroral features appearing in Hubble Space Telescope images of the northern and southern Jovian hemispheres. We investigate the possibility that those ultraviolet auroral structures are associated with energetic particle injections. For this study, we analyze the temporal variations of the longitudinal extent and of the brightness of the auroral structures. Indeed, the injected charged particles drift at different rates due to energy-dependent gradient and curvature drifts, which leads to an increase with time of the longitudinal extent of the feature and of its associated auroral signature. Since the injected energy follows the same trend, the brightness decreases with time. Different processes can generate auroral signatures of plasma injections. We simulate them by considering that pitch angle diffusion is generated by the precipitating energy flux in the ionosphere and whistler-mode waves through electron scattering. We compare the characteristics of the simulated signature with the observed parameters. Following this comparison, we are able to test whether the aforementioned mechanism is responsible for the auroral emission and to infer the typical energy and the spectral index of the energy distribution of the electrons involved in the injection process. [less ▲]

Detailed reference viewed: 15 (3 ULiège)