Article
Geosciences, Multidisciplinary
J. R. Szalay, G. Clark, G. Livadiotis, D. J. McComas, D. G. Mitchell, J. S. Rankin, A. H. Sulaiman, F. Allegrini, F. Bagenal, R. W. Ebert, G. R. Gladstone, W. S. Kurth, B. H. Mauk, P. W. Valek, R. J. Wilson, S. J. Bolton
Summary: Two distinct proton populations, a low-energy core population and a high-energy dispersive conic population, are observed over Jupiter's southern polar cap. The core protons are likely the seed population for the higher-energy dispersive conics, which are accelerated due to transient wave-particle heating. Plasma characteristics and composition suggest that Jupiter's polar-most field lines can be topologically closed, with magnetic footpoints connected to both hemispheres.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
B. H. Mauk, J. R. Szalay, F. Allegrini, F. Bagenal, S. J. Bolton, G. Clark, J. E. P. Connerney, G. R. Gladstone, D. K. Haggerty, P. Kollmann, W. S. Kurth, C. P. Paranicas, A. H. Sulaiman
Summary: By combining multiple ion and electron data sources to diagnose electrostatic potentials both above and below the spacecraft, this study finds that during downward electron broadband events in Zone I, evidence of downward electron electrostatic acceleration can either disappear or endure at some level. Most often, evidence of downward electron electrostatic acceleration is strongly suppressed with strong downward electron broadband acceleration. However, caution must be exercised in these studies as plasmasheet electron precipitation spectra can mimic broadband acceleration spectra.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Geosciences, Multidisciplinary
W. R. Dunn, D. M. Weigt, D. Grodent, Z. H. Yao, D. May, K. Feigelman, B. Sipos, D. Fleming, S. McEntee, B. Bonfond, G. R. Gladstone, R. E. Johnson, C. M. Jackman, R. L. Guo, G. Branduardi-Raymont, A. D. Wibisono, R. P. Kraft, J. D. Nichols, L. C. Ray
Summary: This study presents 14 simultaneous observations of Jupiter's Northern X-ray and ultraviolet (UV) aurorae using the Chandra X-ray Observatory (CXO) and the Hubble Space Telescope (HST) from 2016 to 2019. The observations reveal a lack of detectable X-ray and UV emission from the dark polar region (DPR), indicating that the emission in this region is primarily due to scattered solar radiation rather than other sources.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
V Hue, T. K. Greathouse, G. R. Gladstone, B. Bonfond, J-C Gerard, M. F. Vogt, D. C. Grodent, M. H. Versteeg, J. A. Kammer, G. Clark, R. W. Ebert, R. S. Giles, M. W. Davis, K. Haewsantati, S. J. Bolton, S. M. Levin, J. E. P. Connerney
Summary: Juno-UVS has discovered intriguing features in Jupiter's polar auroral region, characterized by expanding circles of UV-brightness and varying expansion velocities. Color ratio measurements indicate that the mean electron energy responsible for these emissions ranges from 80-160 keV, with events in the outer magnetosphere beyond 100 R-J potentially causing these features. Dayside magnetopause reconnection and Kelvin-Helmholtz instabilities near the magnetopause are expected to generate field-aligned currents that could be the cause of these features.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Geosciences, Multidisciplinary
Duan Zhang, Qing-He Zhang, Kjellmar Oksavik, Tong Xu, Zan-Yang Xing, L. R. Lyons, De-Sheng Han, Hong-Bo Zhang, Yu-Zhang Ma, Ze-Jun Hu, Jian-Jun Liu, Yong Wang, Xiang-Yu Wang
Summary: Throat auroras and polar cap patches are common phenomena in the polar ionosphere resulting from magnetosphere-ionosphere coupling. Observations during periods of radial interplanetary magnetic field (IMF) showed that throat auroras linked to poleward moving ionization patches. Throat auroras were produced by soft-electron precipitation associated with dayside magnetic reconnection and correlated with dayside reconnection events. Dense plasma from lower latitudes was transported poleward to form patches, which moved anti-sunward due to the E x B drift.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Multidisciplinary Sciences
Elias Roussos, Christina Cohen, Peter Kollmann, Marco Pinto, Norbert Krupp, Patricia Goncalves, Konstantinos Dialynas
Summary: Jupiter’s radiation belts contain hazardous radiation and an undetermined mix of heavy ions. Understanding the composition of these ions is crucial in order to understand the role of Jupiter's moons and other sources of energetic ions.
Article
Geochemistry & Geophysics
Thomas Greathouse, Randy Gladstone, Maarten Versteeg, Vincent Hue, Joshua Kammer, Rohini Giles, Michael Davis, Scott Bolton, Steven Levin, John Connerney, Jean-Claude Gerard, Denis Grodent, Bertrand Bonfond, Emma Bunce, Marissa F. Vogt
Summary: The study reveals distinct features of auroral brightness and color ratio in the northern polar region of Jupiter, with the most poleward area displaying high color ratio emissions, while lower color ratio emissions are found in the collar region. Bright emissions in the polar collar are influenced by strong magnetospheric local time control, gradually decreasing in brightness from the dusk side to the midnight side.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2021)
Article
Astronomy & Astrophysics
K. Haewsantati, B. Bonfond, S. Wannawichian, G. R. Gladstone, V. Hue, T. K. Greathouse, D. Grodent, Z. Yao, J. -c. Gerard, R. Guo, S. Elliott, B. H. Mauk, G. Clark, D. Gershman, S. Kotsiaros, W. S. Kurth, J. Connerney, J. R. Szalay, A. Phriksee
Summary: Juno's in situ observations of bright auroral spots on Jupiter have provided unprecedented details about the planet's UV aurorae. The observations reveal that the particle acceleration region is located below the spacecraft, and the northern bright spot in PJ3 shows higher brightness and upward particle flux compared to the southern spots in PJ15 and PJ33. Whistler-mode waves intensify during particle enhancements, suggesting that wave-particle interactions play a role in accelerating the particles responsible for the UV aurorae. Magnetic perturbations during the PJ3 spot detection indicate the presence of significant field-aligned electric currents. The stable positions of the bright spots in System III suggest a fixed relationship to the planet's rotation, but the presence of field-aligned currents leaves open the possibility of a more distant magnetospheric origin.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
K. Haewsantati, B. Bonfond, S. Wannawichian, G. R. Gladstone, V Hue, M. H. Versteeg, T. K. Greathouse, D. Grodent, Z. Yao, W. Dunn, J-C Gerard, R. Giles, J. Kammer, R. Guo, M. F. Vogt
Summary: A systematic analysis of bright spots in Jupiter's polar auroras was conducted, revealing isolated, localized, and transient brightenings in the polar regions. These bright spots exhibit variable emitted power and some show quasiperiodic behavior, reappearing in specific locations within short time intervals. The locations of these bright spots vary between the northern and southern hemispheres, suggesting a complex and dynamic nature of Jupiter's auroral activity.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Astronomy & Astrophysics
F. Allegrini, W. S. Kurth, S. S. Elliott, J. Saur, G. Livadiotis, G. Nicolaou, F. Bagenal, S. Bolton, G. Clark, J. E. P. Connerney, R. W. Ebert, G. R. Gladstone, P. Louarn, B. H. Mauk, D. J. McComas, A. H. Sulaiman, J. R. Szalay, P. W. Valek, R. J. Wilson
Summary: This study investigates the electron partial densities and temperatures in Jupiter's main auroral emission region using data from the Jovian Auroral Distributions Experiment (JADE) on Juno. The results show that electron partial densities and temperatures exhibit consistent trends across different longitudes and hemispheres, with no significant correlation with radial distance.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Astronomy & Astrophysics
A. Masters, W. R. Dunn, T. S. Stallard, H. Manners, J. Stawarz
Summary: Auroral emissions have been extensively observed at the Earth, Jupiter, and Saturn, with Jupiter's polar auroras being brighter and more dynamic. The stronger magnetic field of Jupiter may trigger magnetic reconnection and generate high-energy electron beams, explaining some of the mysterious features of Jupiter's polar auroras.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Marissa F. Vogt, Matthew Rutala, Bertrand Bonfond, John T. Clarke, Luke Moore, Jonathan D. Nichols
Summary: Hubble Space Telescope images of Jupiter's UV aurora show that the main emission occasionally contracts or expands, shifting toward or away from the magnetic pole by several degrees in response to changes in the solar wind dynamic pressure and Io's volcanic activity. The study analyzes HST images from the Galileo era (1996-2003) and compares the latitudinal shifts of the Ganymede footprint and the main auroral emission. The research finds that the Ganymede footprint and main auroral emission typically, but not always, move together and their movements are weakly linked to changes in the current sheet strength measured by Galileo.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
B. Palmaerts, D. Grodent, B. Bonfond, Z. H. Yao, R. L. Guo, J. -c. Gerard, K. Haewsantati, G. R. Gladstone, T. K. Greathouse, V. Hue, J. D. Nichols
Summary: During the period between February and September 2019, the Hubble Space Telescope conducted a large-scale campaign to observe Jupiter's ultraviolet aurorae. The observations revealed the dynamic nature and complex structures of the aurorae, with the help of data from the Juno spacecraft and high-resolution images from HST.
Article
Astronomy & Astrophysics
S. J. Kim, C. K. Sim, T. R. Geballe, Y. L. Yung, S. Miller, S. Lee, C. Tao
Summary: The 8-mu m CH4 north polar hot spot (8CNPHS) of Jupiter, detected in 1980, has been observed for four decades. Its shape and longevity are still not understood, but several mechanisms have been proposed. Recent observations suggest that the 8CNPHS is caused by transient and energetic magnetospheric particles that heat the hydrocarbon layers and energize the spot.
Article
Astronomy & Astrophysics
J. D. Nichols, S. W. H. Cowley
Summary: We compare the intensity of Jupiter's dawn-side main auroral emission observed by the Hubble Space Telescope with the magnitude of the dawn-side magnetospheric equatorial radial current observed by Juno. We find a strong correlation between the two phenomena, providing evidence that the magnetosphere-ionosphere coupling current system plays a key role in powering Jupiter's auroras on the dawn side.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Geosciences, Multidisciplinary
F. Zambon, A. Mura, R. M. C. Lopes, J. Rathbun, F. Tosi, R. Sordini, R. Noschese, M. Ciarniello, A. Cicchetti, A. Adriani, L. Agostini, G. Filacchione, D. Grassi, G. Piccioni, C. Plainaki, G. Sindoni, D. Turrini, S. Brooks, C. Hansen-Koharcheck, S. Bolton
Summary: In this study, the most updated catalog of Io hot spots based on Juno/JIRAM data is presented. A total of 242 hot spots were found, including 23 previously undetected ones. Most of the new hot spots were located at high latitudes (>70 degrees). There was a latitudinal variability and a higher concentration of hot spots in the polar regions, especially in the North. The comparison with previous hot spot catalogs showed that JIRAM detected a high percentage of the total number of hot spots and confirmed the activity of some faint hot spots.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geochemistry & Geophysics
Rohini S. Giles, Vincent Hue, Thomas K. Greathouse, G. Randall Gladstone, Joshua A. Kammer, Maarten H. Versteeg, Bertrand Bonfond, Denis C. Grodent, Jean-Claude Gerard, James A. Sinclair, Scott J. Bolton, Steven M. Levin
Summary: Reflected sunlight observations from the Ultraviolet Spectrograph on the Juno spacecraft revealed significant spatial variability in the distribution of acetylene at Jupiter's south pole. A localized region with enhanced acetylene absorption corresponds to the location of Jupiter's southern polar aurora. This finding highlights the strong influence of charged auroral particles on Jupiter's upper-atmosphere chemistry.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Astronomy & Astrophysics
V. Hue, G. R. Gladstone, C. K. Louis, T. K. Greathouse, B. Bonfond, J. R. Szalay, A. Moirano, R. S. Giles, J. A. Kammer, M. Imai, A. Mura, M. H. Versteeg, G. Clark, J. -c. Gerard, D. C. Grodent, J. Rabia, A. H. Sulaiman, S. J. Bolton, J. E. P. Connerney
Summary: The positions of Jupiter's satellites Io, Europa, and Ganymede vary with time, resulting in changes in the lead angles of their respective auroral footprints. This study provides an empirical model of the equatorial lead angles for the northern and southern hemispheres using spectral images collected by Juno-UVS. The lead angle measurements are used to estimate the travel times of Alfven waves between the three innermost Galilean moons and Jupiter's hemispheres.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
B. H. Mauk, J. R. Szalay, F. Allegrini, F. Bagenal, S. J. Bolton, G. Clark, J. E. P. Connerney, G. R. Gladstone, D. K. Haggerty, P. Kollmann, W. S. Kurth, C. P. Paranicas, A. H. Sulaiman
Summary: By combining multiple ion and electron data sources to diagnose electrostatic potentials both above and below the spacecraft, this study finds that during downward electron broadband events in Zone I, evidence of downward electron electrostatic acceleration can either disappear or endure at some level. Most often, evidence of downward electron electrostatic acceleration is strongly suppressed with strong downward electron broadband acceleration. However, caution must be exercised in these studies as plasmasheet electron precipitation spectra can mimic broadband acceleration spectra.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
James A. Sinclair, Thomas K. Greathouse, Rohini S. Giles, John Lacy, Julianne Moses, Vincent Hue, Denis Grodent, Bertrand Bonfond, Chihiro Tao, Thibault Cavalie, Emma K. Dahl, Glenn S. Orton, Leigh N. Fletcher, Patrick G. J. Irwin
Summary: We used the Gemini-North/Texas Echelon Cross Echelle Spectrograph to observe mid-infrared spectroscopy of Jupiter's mid-to-high latitudes. Our observations capture the auroral emissions and the effects of a solar wind compression, highlighting the interaction between the polar stratosphere and the external space environment. By analyzing the spectra, we found that the brightening of certain emissions is due to upper stratospheric heating, driven by magnetospheric dynamics accelerated by the solar wind enhancement. The south side of Jupiter experiences deeper heating compared to the north, likely due to higher Pedersen conductivities and inhibiting efficient horizontal mixing/advection.
PLANETARY SCIENCE JOURNAL
(2023)
Article
Geosciences, Multidisciplinary
J. D. Nichols, F. Allegrini, F. Bagenal, B. Bonfond, G. B. Clark, J. T. Clarke, J. E. P. Connerney, S. W. H. Cowley, R. W. Ebert, G. R. Gladstone, D. Grodent, D. K. Haggerty, B. Mauk, G. S. Orton, G. Provan, R. J. Wilson
Summary: This study compares Hubble Space Telescope observations of Jupiter's FUV auroras with Juno spacecraft observations in the equatorial middle magnetosphere of Jupiter, and shows that bright patches on the auroras are associated with magnetospheric convection and plasma injections.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Letter
Geosciences, Multidisciplinary
J. Montgomery, R. W. Ebert, F. Allegrini, F. Bagenal, S. J. Bolton, G. A. DiBraccio, S. A. Fuselier, R. J. Wilson, Adam Masters
Summary: In this study, observations of particle and magnetic field in Jupiter's magnetosphere were used to study the Kelvin-Helmholtz instability (KHI) condition. Magnetopause crossings that show evidence of being KH unstable were identified. The results indicate the presence of KH waves at Jupiter's dawn flank, with primary drivers such as high velocity shears and changes in plasma pressure. This study provides important insights into the prevalence of KHI at Juno's dawn magnetopause.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Astronomy & Astrophysics
Wenli Mo, Sarah K. Vines, Robert C. Allen, Caitriona M. Jackman, Chris Paranicas
Summary: Analysis of 2,114 magnetopause crossings at Saturn during the Cassini mission reveals the presence of possible magnetic reconnection and Kelvin-Helmholtz instability at Saturn's magnetopause, suggesting their prevalence in the outer planets. This study provides insight into magnetopause dynamics and plasma transport, contributing to a more comprehensive understanding of outer planets' magnetospheric processes.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
A. Moirano, A. Mura, B. Bonfond, J. E. P. Connerney, V. Dols, D. Grodent, V. Hue, J. C. Gerard, F. Tosi, A. Migliorini, A. Adriani, F. Altieri, C. Castagnoli, A. Cicchetti, B. M. Dinelli, D. Grassi, M. L. Moriconi, R. Noschese, G. Piccioni, C. Plainaki, P. Scarica, G. Sindoni, R. Sordini, D. Turrini, F. Zambon
Summary: One of the features of Jupiter's aurora is the emission caused by the orbital motion of its moon Io. The interaction between Io and the surrounding plasma generates Alfven waves that travel along the magnetic field lines towards Jupiter's ionosphere, causing the production of the Io footprint auroral emission. By studying the position of the Io footprint using JIRAM onboard Juno, researchers can retrieve information on the variability of the Io Plasma Torus and gain insights into the density and temperature variations. The results provide evidence of non-System III variability in the plasma density and temperature, suggesting either local time asymmetry or temporal variability of the torus.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
K. Haewsantati, B. Bonfond, S. Wannawichian, G. R. Gladstone, V. Hue, T. K. Greathouse, D. Grodent, Z. Yao, J. -c. Gerard, R. Guo, S. Elliott, B. H. Mauk, G. Clark, D. Gershman, S. Kotsiaros, W. S. Kurth, J. Connerney, J. R. Szalay, A. Phriksee
Summary: Juno's in situ observations of bright auroral spots on Jupiter have provided unprecedented details about the planet's UV aurorae. The observations reveal that the particle acceleration region is located below the spacecraft, and the northern bright spot in PJ3 shows higher brightness and upward particle flux compared to the southern spots in PJ15 and PJ33. Whistler-mode waves intensify during particle enhancements, suggesting that wave-particle interactions play a role in accelerating the particles responsible for the UV aurorae. Magnetic perturbations during the PJ3 spot detection indicate the presence of significant field-aligned electric currents. The stable positions of the bright spots in System III suggest a fixed relationship to the planet's rotation, but the presence of field-aligned currents leaves open the possibility of a more distant magnetospheric origin.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)