Closed Fluxtubes and Dispersive Proton Conics at Jupiter's Polar Cap

Abstract

The polar regions of Jupiter's magnetosphere are unlike those of any other planet explored by spacecraft with an internal magnetic field. Mercury (e.g., Anderson et al., 2010), Earth (e.g., Smith & Lockwood, 1996), and Saturn (e.g., Jasinski et al., 2014 all exhibit open magnetic topologies in their polar-most regions, where the solar wind is magnetically connected to each of these planets. Evidence for this solar wind connectivity has been found in magnetic field signatures associated with magnetopause transits (e.g., Gurnett et al., 2010) and direct observation of solar wind plasma composition and polar rain -field aligned solar wind strahl electrons that stream along the interconnected magnetic field toward the planet (Winningham & Heikkila, 1974).Jupiter's magnetosphere is internally driven by its strong, rapidly rotating magnetic field and Io's immense heavy ion plasma source. It likely has a fundamentally different magnetospheric interaction with the solar wind than the aforementioned planets ). Jupiter's intense auroral features are primarily driven by plasma processes throughout the magnetosphere and are an important diagnostic in understanding these complex processes (Delamere & Bagenal, 2010). These auroral features (e.g., Grodent, 2016) are typically categorized into: the oval-shaped main auroral emission, Galilean satellite footprint aurora, diffuse emissions equatorward of the main oval, and polar cap emissions poleward of the main oval (Figure 1). Polar cap emissions can exhibit rapid variations (e.g., Bonfond et al., 2016) and the mechanisms sustaining these emissions remain a mystery (e.g., Ebert et al., 2019). As the most poleward auroral features would map to the farthest distances from Jupiter, these auroral emissions have been used to diagnose Jupiter's solar wind interaction. Polar cap emissions have previously been interpreted to infer the presence of a Jovian cusp (Bunce et al., 2004). In contrast, a subsequent analysis interpreted these emissions to indicate a highly complex topological setup where the large majority of

Periodicities and Plasma Density Structure of Jupiter's Dawnside Magnetosphere

“…Szalay et al. (2022) demonstrated that Jupiter's extreme high latitude polar regions contain magnetospheric heavy ions with energy spectra that are consistent with those in the magnetotail. In parallel, recent results from the Grid Agnostic MHD for Extended Research Applications (GAMERA) global simulations (Zhang et al., 2021) also support a largely closed magnetosphere.…”

Proton Equatorial Pitch Angle Distributions in Jupiter's Inner Magnetosphere

“…Unlike heavy ions (O n + /S n + ), which come from the equatorial magnetosphere mainly as pickup‐ions through electron‐impact ionization, proton sources in Jupiter's magnetosphere are less well understood (Bagenal & Dols, 2020). Juno observed up‐welling proton beams contributing 1–5 kg/s of proton outflow from the polar regions of Jupiter (Szalay et al., 2021) along with conic distributions connected to Io's orbit (Clark et al., 2020) and between 3 and 5 R J in the polar‐most regions (Szalay, Clark, et al., 2022). These suggest wave‐particle interactions can also lead to protons being injected into the magnetosphere from Jupiter.…”

Jupiter's Low‐Altitude Auroral Zones: Fields, Particles, Plasma Waves, and Density Depletions

“…Poleward of the zones is the polar cap—a vast and dynamic region where persistent highly field‐aligned, upgoing energetic electrons have been observed (both inverted V and broadband distributions, albeit spatially separated) simultaneously with upgoing broadband emissions interpreted as the whistler mode (Ebert et al., 2017; Elliott, Gurnett, Kurth, Clark, et al., 2018; Elliott, Gurnett, Kurth, Mauk, et al., 2018; Mauk et al., 2020; Paranicas et al., 2018). There has been ongoing research on plasma processes in this region and this will not be the focus of this study (e.g., Elliott et al., 2020; Masters et al., 2021; Shi et al., 2020; Szalay et al., 2022).…”