Jovian Injections Observed at High Latitude

Haggerty, D. K.; Mauk, B. H.; Paranicas, C.; Clark, G.; Kollmann, P.; Rymer, A. M.; Gladstone, G. R.; Greathouse, Thomas; Bolton, S. J.; Levin, S. M.

doi:10.1029/2019gl083442

Cited by 21 publications

(42 citation statements)

References 34 publications

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“…These authors found no injection signatures inside of Io's L‐positions. While we do not know why we are seeing such injections and Dumont et al (2015) did not, we do know that injections observed in situ do not necessarily show up in auroral images (Haggerty et al, 2019). Also, there may be something about the innermost environment that suppresses such auroral manifestations.…”

Section: In Situ Characterizationmentioning

confidence: 71%

“…But, what we can say is that during PJ22 (Figure 9), dynamic injections had recently populated the regions near and even inside Io's orbit ( R = 5.9 RJ). Dynamic injections have been characterized in more distant regions by Mauk et al (1999) and in regions as planetward as L = 7 using Juno by Haggerty et al (2019). One small‐scale injection event studied by Thorne et al (1997), and labeled an “interchange event,” occurred just outside of Io's orbit, at about L = 6.02.…”

Section: In Situ Characterizationmentioning

confidence: 99%

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Juno Energetic Neutral Atom (ENA) Remote Measurements of Magnetospheric Injection Dynamics in Jupiter's Io Torus Regions

et al. 2020

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In planetary magnetospheres, singly charged energetic particles, trapped by the planet's magnetic field, can steal electrons from cold gas atoms and become neutralized. These now energetic neutral atoms (ENAs), no longer confined by the magnetic field, can travel out of the system similar to photons leaving a hot oven. ENAs have been used to image magnetospheric processes at Earth, Jupiter, and Saturn. At Jupiter, the opportunities to image the magnetosphere have been limited and always from the perspective of the near-equatorial plane at distance >139 RJ. The polar-orbiting Juno mission carries the Jupiter Energetic particle Detector Instrument that is serendipitously sensitive to ENAs with energies >50 keV, provided that there are no charged particles in the environment to mask their presence. Here we report on the first ENA observations of Jupiter's magnetosphere from a nonequatorial perspective. In this brief report we concentrate on emissions seen during Perijove 22 (PJ22) during very active conditions and compare them with emissions during the inactive Perijove 23 (PJ23). We observe, and discriminate between, distinct ENA signatures from the neutral gases occupying the orbit of Io (away from Io itself), the orbit of Europa (away from Europa), and from Jupiter itself. Strong ENA emissions from Io's orbit during PJ22 are associated with energetic particle injections observed near Io's orbit several hours earlier. Some injections occurred planetward of Io's L-shell (magnetic position), somewhat of a surprise given that injections are thought to be driven by outward transport of plasmas generated by Io.Plain Language Summary In the space environments of magnetized planets (magnetospheres), magnetic fields trap and confine energetic charged particles like protons and singly charged heavier ions. These ions can neutralize themselves by stealing electrons from cold gas atoms within the same environment. They become energetic neutral atoms (ENAs), and no longer confined by the magnetic field, can travel out of the system in a fashion similar to light leaving a hot oven. ENAs have been used to image magnetospheric processes at Earth, Jupiter, and Saturn. At Jupiter, the opportunities to image the magnetosphere have been limited and always from the perspective of the near-equatorial plane at large distances (>139 RJ). The polar-orbiting Juno mission carries the Jupiter Energetic particle Detector Instrument that is serendipitously sensitive to ENAs with energies >50 keV, provided that there are no charged particles in the environment to mask their presence. Here we report on the first ENA observations of Jupiter's magnetosphere from a nonequatorial perspective. That perspective allows us to observe distinct ENA signatures from the neutral gases occupying the orbit of the moon Io (away from Io itself), the gases in the orbit of the moon Europa (away from Europa), and from Jupiter itself.

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Section: In Situ Characterizationmentioning

confidence: 71%

Section: In Situ Characterizationmentioning

confidence: 99%

Juno Energetic Neutral Atom (ENA) Remote Measurements of Magnetospheric Injection Dynamics in Jupiter's Io Torus Regions

et al. 2020

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“…The inward‐moving fluxtubes containing energetic particles are often called “injections.” Such injections of energetic particles have been observed in the Io‐Europa environment (Haggerty et al, 2019; Mauk et al, 1999) and are clearly a major element in radial transport within these regions. The structures are much broader in scale than the events observed in magnetometer data by Russell et al (2005), and their dispersion in energy suggests such structures have aged (presumably as they travelled inward).…”

Section: Plasma Torusmentioning

confidence: 71%

The Space Environment of Io and Europa

2020

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The Galilean moons play major roles in the giant magnetosphere of Jupiter. At the same time, the magnetospheric particles and fields affect the moons. The impact of magnetospheric ions on the moons' atmospheres supplies clouds of escaping neutral atoms that populate a substantial fraction of their orbits. At the same time, ionization of atoms in the neutral cloud is the primary source of magnetospheric plasma. The stability of this feedback loop depends on the plasma/moon-atmosphere interaction. The purpose of this review is to describe the physical processes that shape the space environment around the two innermost Galilean moons-Io and Europa-and to show their impact from the planet Jupiter out into interplanetary space.

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“…Pertinent to this work, “auroral injection” events are transient auroral structures occurring between the main auroral oval and the footprint of Io. These auroral structures are thought to be the consequence of energetic particles injected toward the planet in the middle magnetosphere (Haggerty et al, 2019; Mauk et al, 1997, 2002). An understanding of auroral injections is crucial for understanding plasma transport in the magnetosphere and the ionosphere.…”

Section: Introductionmentioning

confidence: 99%

“…Plasma injections are a key consequence of magnetic dipolarizations at Earth (Gabrielse et al, 2016; Ohtani et al, 2007), but such a connection for Jupiter is not yet confirmed by observations. Auroral injection signatures are a counterpart of magnetospheric plasma injections at Jupiter (Dumont et al, 2014; Haggerty et al, 2019; Mauk et al, 2002). Haggerty et al (2019) have also revealed that a plasma injection does not always produce an auroral injection signature.…”

Section: Introductionmentioning

confidence: 99%

Reconnection‐ and Dipolarization‐Driven Auroral Dawn Storms and Injections

et al. 2020

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Jupiter displays many distinct auroral structures, among which auroral dawn storms and auroral injections are often observed contemporaneously. However, it is unclear if the contemporaneous nature of the observations is a coincidence or part of an underlying physical connection. We show six clear examples from a recent Hubble Space Telescope campaign (GO‐14634) that each display both auroral dawn storms and auroral injection signatures. We found that these conjugate phenomena could exist during intervals of either relatively low or high auroral activity, as evidenced by the varied levels of total auroral power. In situ observations of the magnetosphere by Juno show a strong magnetic reconnection event inside of 45 Jupiter radii (RJ) on the predawn sector, followed by two dipolarization events within the following 2 hr, coincident with the auroral dawn storm and auroral injection event. We therefore suggest that the auroral dawn storm is the manifestation of magnetic reconnection in the dawnside magnetosphere. The dipolarization region is mapped to the auroral injection, strongly suggesting that this was associated with the auroral injection. Since magnetic reconnection and dipolarization are physically connected, we therefore suggest that the often‐conjugate auroral dawn storm and auroral injection events are also physically connected consequences.

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Jovian Injections Observed at High Latitude

Cited by 21 publications

References 34 publications

Juno Energetic Neutral Atom (ENA) Remote Measurements of Magnetospheric Injection Dynamics in Jupiter's Io Torus Regions

Juno Energetic Neutral Atom (ENA) Remote Measurements of Magnetospheric Injection Dynamics in Jupiter's Io Torus Regions

The Space Environment of Io and Europa

Reconnection‐ and Dipolarization‐Driven Auroral Dawn Storms and Injections

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