Ice giant magnetospheres

Paty, C. S.; Arridge, C. S.; Cohen, I. J.; DiBraccio, G. A.; Ebert, R. W.; Rymer, A. M.

doi:10.1098/rsta.2019.0480

Cited by 19 publications

(13 citation statements)

References 119 publications

(222 reference statements)

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“…Their interaction with the solar wind in the outer heliosphere in turn shapes asymmetric magnetospheres of comparable sizes, twisted by the fast planetary rotation (approx. 17 h and 16 h, respectively), with weak internal plasma sources and complex dynamics [5]. The large magnetic tilt implies that the solar wind/magnetosphere geometry radically varies at timescales ranging from seasons (with revolution periods of 84 and 165 years, respectively) down to a fraction of a planetary rotation.…”

Section: Introductionmentioning

confidence: 99%

Auroral emissions from Uranus and Neptune

Lamy

2020

Phil. Trans. R. Soc. A.

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Uranus and Neptune possess highly tilted/offset magnetic fields whose interaction with the solar wind shapes unique twin asymmetric, highly dynamical, magnetospheres. These radiate complex auroral emissions, both reminiscent of those observed at the other planets and unique to the ice giants, which have been detected at radio and ultraviolet (UV) wavelengths to date. Our current knowledge of these radiations, which probe fundamental planetary properties (magnetic field, rotation period, magnetospheric processes, etc.), still mostly relies on Voyager 2 radio, UV and in situ measurements, when the spacecraft flew by each planet in the 1980s. These pioneering observations were, however, limited in time and sampled specific solar wind/magnetosphere configurations, which significantly vary at various timescales down to a fraction of a planetary rotation. Since then, despite repeated Earth-based observations at similar and other wavelengths, only the Uranian UV aurorae have been re-observed at scarce occasions by the Hubble Space Telescope. These observations revealed auroral features radically different from those seen by Voyager 2, diagnosing yet another solar wind/magnetosphere configuration. Perspectives for the in-depth study of the Uranian and Neptunian auroral processes, with implications for exoplanets, include follow-up remote Earth-based observations and future orbital exploration of one or both ice giant planetary systems. This article is part of a discussion meeting issue ‘Future exploration of ice giant systems’.

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Section: Introductionmentioning

confidence: 99%

Auroral emissions from Uranus and Neptune

Lamy

2020

Phil. Trans. R. Soc. A.

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“…Radiation belts magnetically trap and energize charged particles around a planet and are as diverse as the planets they encompass. Uranus's radiation belts are especially interesting, as Voyager 2 observations did not confirm our expectations (Kollmann et al 2020;Paty et al 2020). For the particles to accumulate to high intensities, the radiation belts need to draw from a large reservoir of lower-energy plasma (as illustrated in Figure 4(b)) and/or lose the accelerated particles very slowly.…”

Section: Magnetospheric Sciencementioning

confidence: 64%

“…Understand how internal and external drivers generate plasma structures and transport within Uranus's magnetosphere. The magnetosphere of Uranus (Stone & Miner 1986;Paty et al 2020) offers a unique configuration that provides an opportunity to understand the drivers of magnetospheric dynamics throughout the solar system. With the planetary rotation axis tilted by 98°relative to the ecliptic plane and a magnetic field axis tilted by ∼59°with respect to Uranus's rotation axis, the orientation of the magnetic field (Figure 4 Plasma transport within a planetary magnetosphere may generally be driven by external and/or internal forces.…”

Section: Magnetospheric Sciencementioning

confidence: 99%

The Case for a New Frontiers–Class Uranus Orbiter: System Science at an Underexplored and Unique World with a Mid-scale Mission

et al. 2022

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Current knowledge of the Uranian system is limited to observations from the flyby of Voyager 2 and limited remote observations. However, Uranus remains a highly compelling scientific target due to the unique properties of many aspects of the planet itself and its system. Future exploration of Uranus must focus on cross-disciplinary science that spans the range of research areas from the planet’s interior, atmosphere, and magnetosphere to the its rings and satellites, as well as the interactions between them. Detailed study of Uranus by an orbiter is crucial not only for valuable insights into the formation and evolution of our solar system but also for providing ground truths for the understanding of exoplanets. As such, exploration of Uranus will not only enhance our understanding of the ice giant planets themselves but also extend to planetary dynamics throughout our solar system and beyond. The timeliness of exploring Uranus is great, as the community hopes to return in time to image unseen portions of the satellites and magnetospheric configurations. This urgency motivates evaluation of what science can be achieved with a lower-cost, potentially faster-turnaround mission, such as a New Frontiers–class orbiter mission. This paper outlines the scientific case for and the technological and design considerations that must be addressed by future studies to enable a New Frontiers–class Uranus orbiter with balanced cross-disciplinary science objectives. In particular, studies that trade scientific scope and instrumentation and operational capabilities against simpler and cheaper options must be fundamental to the mission formulation.

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“…For the Uranian field, we used the internal hexadecapole AH5 magnetic field model derived from Voyager 2 Magnetometer data and Ultraviolet Spectrometer observations of aurora (Herbert, 2009) (Figure S1) at at the epoch of the Voyager 2 flyby (1986). Given the estimated magnetopause distance of ~19𝑅 U , all of the moons with the occasional exception of Oberon and Titania should spend essentially all of their time within the magnetosphere (Paty et al, 2020). Furthermore, the large angle between Uranus's spin and offset dipole axes means that the moons will spend relatively little time near the magnetic equator where field perturbations associated with a magnetospheric plasma sheet could mask the induction signals (C. J. .…”

Section: Driving Fieldmentioning

confidence: 99%