Magnetospheric Science Objectives of the Juno Mission

Bagenal, F.; Adriani, A.; Allegrini, F.; Bolton, S. J.; Bonfond, Bertrand; Bunce, E. J.; Connerney, J. E. P.; Cowley, S. W. H.; Ebert, R. W.; Gladstone, G. R.; Hansen, C. J.; Kŭrth, W. S.; Levin, S. M.; Mauk, B. H.; McComas, D. J.; Paranicas, C.; Santos-Costa, Daniel; Thorne, R. M.; Valek, P. W.; Waite, J. H.; Zarka, Philippe

doi:10.1007/978-94-024-1560-5_3

Cited by 101 publications

(145 citation statements)

References 218 publications

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“…In contrast, interactions in multiple-satellite systems, such as the one around Jupiter, can prevent the total tidal synchronization of the close-in satellites through resonant orbital interactions and a pumping of the orbital eccentricity (see Peale 1999 and references therein). These effects could sustain significant tidal interactions throughout the system age that contribute to the internal satellite heat flux and the generation of prominent volcanism, and consequently a plasma disk, without significantly spinning down the host brown dwarf; for example, the Jovian rotational period is ∼10 hr (Bagenal et al 2014). If planetary companions are a necessary condition, these additional considerations may drive the difference between the overall UCD planet occurrence rate and the prevalence of UCD auroral emissions.…”

Section: The Possible Role Of Planetary Companionsmentioning

confidence: 99%

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A Panchromatic View of Brown Dwarf Aurorae

Pineda

Hallinan

Kao

2017

ApJ

118

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Stellar coronal activity has been shown to persist into the low-mass star regime, down to late M-dwarf spectral types. However, there is now an accumulation of evidence suggesting that at the end of the main sequence, there is a transition in the nature of the magnetic activity from chromospheric and coronal to planet-like and auroral, from local impulsive heating via flares and MHD wave dissipation to energy dissipation from strong large-scale magnetospheric current systems. We examine this transition and the prevalence of auroral activity in brown dwarfs through a compilation of multiwavelength surveys of magnetic activity, including radio, X-ray, and optical. We compile the results of those surveys and place their conclusions in the context of auroral emission as a consequence of large-scale magnetospheric current systems that accelerate energetic electron beams and drive the particles to impact the cool atmospheric gas. We explore the different manifestations of auroral phenomena, like Hα, in brown dwarf atmospheres and define their distinguishing characteristics. We conclude that large-amplitude photometric variability in the near-infrared is most likely a consequence of clouds in brown dwarf atmospheres, but that auroral activity may be responsible for long-lived stable surface features. We report a connection between auroral Hα emission and quiescent radio emission in electron cyclotron maser instability pulsing brown dwarfs, suggesting a potential underlying physical connection between quiescent and auroral emissions. We also discuss the electrodynamic engines powering brown dwarf aurorae and the possible role of satellites around these systems both to power the aurorae and seed the magnetosphere with plasma.

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Section: The Possible Role Of Planetary Companionsmentioning

confidence: 99%

“…at decimeter wavelengths (see Bagenal et al 2014 and references therein). If similar structures exist on these brown dwarfs, they could generate the quiescent emission at GHz and higher frequencies, given the comparatively stronger magnetic field strength of brown dwarfs relative to Jupiter.…”

Section: Quiescent Radio Emissionmentioning

confidence: 99%

A Panchromatic View of Brown Dwarf Aurorae

Pineda

Hallinan

Kao

2017

ApJ

118

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“…A key difference in the Jovian model from equivalent terrestrial models is the effect of the Jovian equatorial plasma sheet. As the plasma density in the plasma sheet is orders of magnitude higher than in the higher‐latitude regions (lobes), the Alfvén travel time is dominated by the plasma sheet thickness and Alfvén speed (see figure 27 in Bagenal et al, ). Conservation of energy flux also means that the magnetic perturbation amplitude is maximized inside the plasma sheet.…”

Section: Introductionmentioning

confidence: 99%

First Evidence for Multiple‐Harmonic Standing Alfvén Waves in Jupiter's Equatorial Plasma Sheet

Manners

Masters

2019

Geophysical Research Letters

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Quasiperiodic pulsations in the ultralow‐frequency band are ubiquitously observed in the Jovian magnetosphere, but their source and distribution have until now been a mystery. Standing Alfvén waves on magnetic field lines have been proposed to explain these pulsations and their large range in observed periods. However, in situ evidence in support of this mechanism has been scarce. Here we use magnetometer data from the Galileo spacecraft to report first evidence of a multiple‐harmonic ultralow‐frequency event in Jupiter's equatorial plasma sheet. The harmonic periods lie in the 4‐ to 22‐min range, and the nodal structure is confined to the plasma sheet. Polarization analysis reveals several elliptically polarized odd harmonics and no presence of even harmonics. The harmonic periods, their polarization, and the confinement of the wave to the plasma sheet are strong evidence supporting the standing Alfvén wave model. Multiple‐harmonic waves therefore potentially explain the full range of periods in quasiperiodic pulsations in Jupiter's magnetosphere.

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“…On 5 August 2011 the Juno spacecraft was successfully launched and arrived at Jupiter on 5 July 2016 (UT), conducting in situ and remote observations of the magnetosphere, atmosphere, and interior of the planet. These observations address the mission's primary science objectives, exploration of the origin and history of the gas giant, and exploration of the polar magnetosphere and auroral zones [ Bolton and Team , ; Bagenal et al , ]. The Juno spacecraft spent 5 years traveling to Jupiter, by way of a deep space maneuver on 12 September 2012, followed by an Earth gravity assist on 9 October 2013, before setting a course for Jupiter.…”

Section: Introductionmentioning

confidence: 99%

“…Shaded regions in Figure identify the times that these three missions obtained observations at distances <6 AU. The solar wind plays a role, as yet perhaps poorly understood, in Jovian magnetospheric dynamics and auroral processes [ Baron et al , ; Bagenal et al , ]. Investigations of the evolution of the solar wind during the current solar cycle will aid in putting Juno magnetospheric investigations into context of this current abnormal solar cycle.…”

Section: Introductionmentioning

confidence: 99%

The interplanetary magnetic field observed by Juno enroute to Jupiter

Gruesbeck

Gershman

Espley

et al. 2017

Geophysical Research Letters

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The Juno spacecraft was launched on 5 August 2011 and spent nearly 5 years traveling through the inner heliosphere on its way to Jupiter. The Magnetic Field Investigation was powered on shortly after launch and obtained vector measurements of the interplanetary magnetic field (IMF) at sample rates from 1 to 64 samples/second. The evolution of the magnetic field with radial distance from the Sun is compared to similar observations obtained by Voyager 1 and 2 and the Ulysses spacecraft, allowing a comparison of the radial evolution between prior solar cycles and the current depressed one. During the current solar cycle, the strength of the IMF has decreased throughout the inner heliosphere. A comparison of the variance of the normal component of the magnetic field shows that near Earth the variability of the IMF is similar during all three solar cycles but may be less at greater radial distances.

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Magnetospheric Science Objectives of the Juno Mission

Cited by 101 publications

References 218 publications

A Panchromatic View of Brown Dwarf Aurorae

A Panchromatic View of Brown Dwarf Aurorae

First Evidence for Multiple‐Harmonic Standing Alfvén Waves in Jupiter's Equatorial Plasma Sheet

The interplanetary magnetic field observed by Juno enroute to Jupiter

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