Survey of Jupiter's Dawn Magnetosheath Using Juno

Ranquist, D. A.; Bagenal, F.; Wilson, R. J.; Hospodarsky, G. B.; Ebert, R. W.; Allegrini, F.; Valek, P. W.; McComas, D. J.; Connerney, J. E. P.; Kurth, W. S.; Bolton, S. J.

doi:10.1029/2019ja027382

Cited by 25 publications

(53 citation statements)

References 90 publications

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“…Between 60 and 110 R J , an indication of magnetosheath encounters is shown with enhancements in counts. Variability of magnetosheath distance is due to a change in the upstream solar wind conditions (e.g., McComas et al, ; Ranquist et al, ; Wilson et al, ). The equatorially confined plasma observed between ∼10 and ∼50 R J represents plasma sheet ions.…”

Section: Instrumentation and Datamentioning

confidence: 99%

Survey of Ion Properties in Jupiter's Plasma Sheet: Juno JADE‐I Observations

et al. 2020

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This study presents a survey of ion flow speed, density, temperature, and composition observed by the Jovian Auroral Distributions Experiment Ion (JADE-I) sensor on Juno from 10-40 R J in the dawn to midnight sector of Jupiter's magnetosphere. The survey covers Juno orbits 5-22, and the observations are separated by equatorial (|z mag [R J ]| ≤ 1.5) and off-equator (|z mag [R J ]| > 1.5) regions. Plasma parameters for H + , O + , O 2+ , O 3+ , Na + , S + , S 2+ , and S 3+ are derived by forward modeling JADE-I's energy-per-charge versus time-of-flight spectra using omnidirectional averaged convected kappa distributions and modeled instrument responses. O + and S 2+ are resolved via a ray-tracing simulation based on carbon-foil-effects. The ion flow speed increases with radial distance and is comparable to rigid corotation speed out to ∼20 R J . Ion number densities decrease with radial distance, the primary species being H + , O + , and S 2+ . The relative contribution of H + and S 2+ increases and decreases, respectively, in the off-equator regions, supporting the interpretation that the latitudinal distribution of ions is mass dependent. The O + to S 2+ and O n+ to S n+ number density ratios are variable, the 5 R J bin averages for O + to S 2+ ranging from ∼0.75-1.5 (equator) and ∼1.1-1.8 (off-equator) and O n+ to S n+ from ∼0.6-0.9 (equator) and ∼0.8-1.1 (off-equator). Both proton and heavy ion temperatures show order of magnitude increases between 10 and 20 R J and range from ∼100 eV to 10 keV and 1 keV to a few tens of keV, respectively. Plain Language Summary The Jovian Auroral Distributions Experiment (JADE) on Juno hascontinuously investigated the plasma environment in Jupiter's magnetosphere since its arrival in August 2016. The polar-orbiting spacecraft enables JADE to explore both equatorial and off-equator regions of Jupiter's plasma sheet. In this study, we present plasma sheet ion characteristics such as ion composition, flow speed, and temperatures for H + , O + , O 2+ , O 3+ , Na + , S + , S 2+ , and S 3+ that are originating from the innermost Galilean satellite Io. A spatial dependence of ion characteristics is discussed and compared to previous observations. While the density profiles agree well with the Voyager-based studies, temperatures found in this study show at least an order of magnitude higher values. A new addition to this paper is that the latitudinal distribution of ions shows trend in the mass. Relative composition of protons increases compared to the heavier ions in the off-equator regions. These observations provide insights on how the ions are distributed throughout Jupiter's magnetosphere and improve our current understanding on ion dynamics in the plasma sheet. Key Points:• Ion flow speed, number density, temperature, and composition in Jupiter's plasma sheet show radial and/or latitudinal trends • H + , O + , and S 2+ are the primary ions, the contribution of H + and S 2+ increasing and decreasing, respectively, in the off-equator region • The O + to S 2+ density ratio is vari...

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Section: Instrumentation and Datamentioning

confidence: 99%

Survey of Ion Properties in Jupiter's Plasma Sheet: Juno JADE‐I Observations

et al. 2020

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“…The second assumption is a looser variation on the assumption that the magnetosheath magnetic field lies tangentially to the magnetopause surface. Unfortunately, the stricter assumption breaks down since Ranquist et al (2019) showed that the magnetosheath magnetic field direction is frequently 25° farther away from aligned with the X axis than the velocity vectors. This implies that the plasma flow is more likely to lie tangentially to the magnetopause surface than the magnetic field.…”

Section: Methodsmentioning

confidence: 99%

“…These results can be used to better understand the preferential rotation of the magnetic field in the magnetosheath to align with Jupiter's spin axis (Erkaev et al, 1996;Farrugia et al, 1998;Ranquist et al, 2019), which in turn changes the dynamics of magnetic reconnection and the Kelvin-Helmholtz instability at the Figure 3. The equatorial portion of the Joy et al (2002) model combined with a polar flattening of 1.29 ± 0.29 for the (a) JSN X-Z cross section and (b) JSN Y-Z cross section at the terminator.…”

Section: Figure 3 Combines Thementioning

confidence: 99%

“…This study uses the same Juno data set published by Ranquist et al (2019) on Jupiter's dawn magnetosheath. This includes particle data from the Jovian Auroral Distributions Experiment (JADE) (McComas et al, 2017), magnetic field data from the Magnetic Field Investigation (MAG) (Connerney et al, 2017), and radio and plasma wave data from the Juno Waves Investigation (Waves) (Kurth et al, 2017).…”

Section: Datamentioning

confidence: 99%

“…When JADE data were unavailable, MAG and Waves data determined the boundaries of the magnetosheath. As discussed in Ranquist et al (2019), to avoid contamination from the boundary/depletion layer, they removed 66 min of data near each magnetopause crossing and 1 min from each bow shock crossing. They then dropped the magnetosheath crossing if less than 2 hr remained.…”

Section: Datamentioning

confidence: 99%

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Polar Flattening of Jupiter's Magnetosphere

Ranquist

Bagenal

Wilson

2020

Geophysical Research Letters

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Jupiter's magnetosphere is filled with plasma that expands from Io into an equatorial plasma disk, which preferentially inflates the magnetosphere against the solar wind equatorially. This results in a polar flattened magnetosphere and changes the dynamics between the solar wind and the magnetopause boundary. The degree of polar flattening at Jupiter, however, is not well known because no spacecraft has traversed the magnetopause at high latitudes. Instead, estimates must be made from much lower latitudes. In this study, we present a new method of estimating the large‐scale shape of magnetospheres by using magnetic field draping within the magnetosheath. Utilizing data of Jupiter's dawn magnetosheath from the Juno spacecraft, we estimate the ratio of the semimajor to semiminor axes of the Jupiter‐Sun‐North Y‐Z elliptical cross section of Jupiter's magnetopause is 1.29 ± 0.29.

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Observation of Kolmogorov Turbulence in the Jovian Magnetosheath From JADE Data

Bandyopadhyay

McComas

Szalay

et al. 2021

Geophysical Research Letters

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The solar wind is the supersonic outward flow of plasma from the Sun. When the turbulent solar wind approaches Jupiter, it crosses a bow shock, which slows the plasma to subsonic speeds and causes significant increase in the plasma's density, temperature, and turbulence level. This region of subsonic plasma between the bow shock and magnetosphere is known as the magnetosheath. Magnetosheath of different sizes with varying properties is seen in the magnetospheres of Earth, Saturn, and Jupiter (Bagenal et al., 2017). The bounding surface of the magnetosphere is called the magnetopause. The magnetopause is the region where the source of the magnetic field changes: inside the magnetopause, the controlling magnetic field is that of Jupiter; while outside, it is the solar wind magnetic field.The magnetosheath is the interface of the solar wind-magnetosphere interaction, affecting the physical processes occurring within Jupiter's magnetopause. The magnetosheath magnetic field and plasma interact at the magnetopause and, consequently, with Jupiter's magnetosphere (Ranquist et al., 2020). Therefore, studying the properties of turbulence in the magnetosheath helps to better understand the dynamical coupling between the solar wind and the magnetosphere and to improve the current models. In addition, the interest in exploring plasma turbulence near Jupiter also lies in its plasma conditions: it has a strong magnetic field, a broad range of plasma β (the ratio of thermal pressure to magnetic pressure) values (Ranquist et al., 2019), and a very large system size, the combination makes the Jovian magnetospheric system a

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Survey of Jupiter's Dawn Magnetosheath Using Juno

Cited by 25 publications

References 90 publications

Survey of Ion Properties in Jupiter's Plasma Sheet: Juno JADE‐I Observations

Survey of Ion Properties in Jupiter's Plasma Sheet: Juno JADE‐I Observations

Polar Flattening of Jupiter's Magnetosphere

Observation of Kolmogorov Turbulence in the Jovian Magnetosheath From JADE Data

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