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
Phillip H. Phipps, Paul Withers, Dustin R. Buccino, Yu-Ming Yang, Marzia Parisi
Summary: This study reports measurements of the total electron content through the Io plasma torus by the Juno spacecraft, revealing that the torus locations depend on longitude, the peak total electron content values vary with time, and the scale heights may depend on longitude and/or time. Additional analysis of observations by the Juno spacecraft is needed to further understand the roles of longitude, time, and the Io phase angle in shaping the density structure of the Io plasma torus.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Geosciences, Multidisciplinary
A. H. Sulaiman, J. R. Szalay, G. Clark, F. Allegrini, F. Bagenal, M. J. Brennan, J. E. P. Connerney, V. Hue, W. S. Kurth, R. L. Lysak, J. D. Nichols, J. Saur, S. J. Bolton
Summary: Juno's highly inclined orbits provide opportunities to study the magnetic field lines connected to the orbit of Io. Its payload allows for remote-sensing and in-situ measurements of the Io-Jupiter interaction. The study presents the analysis of Alfven Poynting fluxes and field-aligned current densities along field lines connected to Io and its orbit.
GEOPHYSICAL RESEARCH LETTERS
(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)
Article
Astronomy & Astrophysics
Xiaoyi Tan, Fei He, Masato Kagitani, Yong Zhao, Zhonghua Yao, Zhaojin Rong, Yong Wei
Summary: In this study, a three-dimensional model of the Io plasma torus is compiled and simulated emissions are conducted, which match well with previous observations. This work provides a convenient tool for observing and obtaining physical parameters of the plasma torus.
EARTH AND SPACE SCIENCE
(2023)
Article
Astronomy & Astrophysics
C. K. Louis, P. Louarn, B. Collet, N. Clement, S. Al Saati, J. R. Szalay, V. Hue, L. Lamy, S. Kotsiaros, W. S. Kurth, C. M. Jackman, Y. Wang, M. Blanc, F. Allegrini, J. E. P. Connerney, D. Gershman
Summary: This study focuses on the detection and characterization of radio sources associated with the Galilean moons Io, Europa, and Ganymede at Jupiter. Using data from the Juno spacecraft, this research suggests that the Cyclotron Maser Instability is responsible for the radio signals. The study also highlights the importance of Alfven perturbations and currents in amplifying the radio emissions.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Chihiro Tao, Tomoki Kimura, Elena A. Kronberg, Fuminori Tsuchiya, Go Murakami, Atsushi Yamazaki, Marissa F. Vogt, Bertrand Bonfond, Kazuo Yoshioka, Ichiro Yoshikawa, Yasumasa Kasaba, Hajime Kita, Shogo Okamoto
Summary: Quasi-periodic variations of a few to several days were observed in the energetic plasma and magnetic dipolarization in Jupiter's magnetosphere. The differences in periodicities between volcanically active and quiet periods were found to be insignificant based on long-term monitoring of Jupiter's northern aurora.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Yuxian Wang, Jian Yang, Xiaocheng Guo, Chi Wang, Michel Blanc
Summary: The dynamics of the Jovian inner magnetosphere, driven by centrifugal convection, are simulated using the Rice Convection Model-Jupiter. The study finds that the interchange instability and convection are significantly affected by the ionospheric conductances and Io source rate. Additionally, it is observed that a uniform Hall conductance has little influence on the convection system, while the inhomogeneity of the Hall conductance can regulate plasma convection.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Yash Sarkango, James A. Slavin, Xianzhe Jia, Gina A. DiBraccio, George B. Clark, Weijie Sun, Barry H. Mauk, William S. Kurth, George B. Hospodarsky
Summary: We expand on previous observations of magnetic reconnection in Jupiter's magnetosphere by surveying ion-inertial scale plasmoids in the Jovian magnetotail. Our results demonstrate that magnetic reconnection in the Jovian magnetotail occurs at ion scales like in other space environments. Ion-scale plasmoids would need to be released every 0.1 s or less to match the canonical 1 ton/s rate of plasma production due to Io.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
H. T. Smith, R. Koga, F. Tsuchiya, V. J. Dols
Summary: Io is an important source of particles for Jupiter's magnetosphere, and the JAXA Hisaki mission provides valuable observations of Io's neutral particle populations. The mission's UV neutral oxygen line of sight observations allow for direct observation of the neutral tori and provide insights into the sources and mechanisms from Io. However, 3-D modeling is necessary to interpret the complex observational geometries.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Geochemistry & Geophysics
Leonardo Carrer, Dustin M. Schroeder, Andrew Romero-Wolf, Paul A. Ries, Lorenzo Bruzzone
Summary: The article investigates the impact of Jovian DAM characteristics on radar sounding performance, evaluating recent radio spectra and selected radar missions for Ganymede and Europa. Results show that Jovian DAM is not perfectly white noise and has variable occurrence probabilities, with sporadic occurrence in some frequency ranges.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2021)
Article
Multidisciplinary Sciences
Sergey Ershkov, Dmytro Leshchenko
Summary: This paper applies recent ansatz to estimate the stability of Laplace resonance among Galilean moons, finding that the resonance should be valid and stable in the future, with possible chaotic perturbations of less than 0.1%. Furthermore, it is discovered that there is a net transfer of angular momentum between Io and Europa, resulting in tidal heating.
ANAIS DA ACADEMIA BRASILEIRA DE CIENCIAS
(2021)
Article
Geochemistry & Geophysics
Minyi Long, Binbin Ni, Xing Cao, Xudong Gu, Peter Kollmann, Qiong Luo, Ruoxian Zhou, Yingjie Guo, Deyu Guo, Yuri Y. Shprits
Summary: This study quantitatively and comprehensively investigates the absorption probabilities and particle lifetimes due to encounters with four of Jupiter's inner moons. The results show that the particle lifetimes vary dramatically depending on the particle equatorial pitch angle, kinetic energy, and moon orbit. The lifetimes are shortest for encounters with Io and longest for encounters with Thebe. Additionally, the lifetimes of energetic protons decrease with increasing kinetic energy, while the lifetimes of energetic electrons remain roughly constant at higher energies.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2022)
Article
Geochemistry & Geophysics
Naoya Momoki, Hiroaki Toh
Summary: This study updates the model of Jupiter's magnetospheric field using data from multiple missions, revealing long-term variations in current sheet and magnetospheric field parameters. The updated model is valuable for studying dynamic events in the magnetosphere and probing the Galilean icy moons.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2022)
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
K. Yamamoto, K. Seki, A. Matsuoka, S. Imajo, M. Teramoto, M. Kitahara, Y. Kasahara, A. Kumamoto, F. Tsuchiya, M. Shoji, S. Nakamura, Y. Miyoshi, I. Shinohara
Summary: This study conducted a statistical analysis of multi-harmonic toroidal waves using data from the Arase satellite observations. The results showed that the occurrence rate and wave power of these waves are correlated with solar wind velocity and interplanetary magnetic field cone angle. The median frequency of the waves on the dayside is correlated with the upstream wave frequency predicted by the ion beam instability theory. Kelvin-Helmholtz instability, upstream waves, and dynamic pressure fluctuations are suggested as possible sources of these waves.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Balazs Heilig, Claudia Stolle, Guram Kervalishvili, Jan Rauberg, Yoshizumi Miyoshi, Fuminori Tsuchiya, Atsushi Kumamoto, Yoshiya Kasahara, Masafumi Shoji, Satoko Nakamura, Masahiro Kitahara, Iku Shinohara
Summary: This study investigates the relationship between the plasmapause (PP) and various ionospheric phenomena, such as the midlatitude ionospheric trough (MIT). The research uses Swarm observations and PP positions to address unanswered questions, revealing the correlation and time lag between these phenomena.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
M. Teramoto, Y. Miyoshi, A. Matsuoka, Y. Kasahara, A. Kumamoto, F. Tsuchiya, M. Nose, S. Imajo, M. Shoji, S. Nakamura, M. Kitahara, I. Shnohara
Summary: Using magnetic field and electron density data from the Arase satellite, this study investigates the spatial properties of Pi2 pulsations in relation to the plasmapause in the inner magnetosphere. The results show that high-coherence magnetic field disturbances are mainly identified in the radial and compressional components on the nightside in the pre-midnight sector. By determining the location of the plasmapause using electron densities, it is found that the high-coherence events exhibit specific power ratio and phase changes near the plasmapause, indicating excitation by the plasmaspheric virtual resonance mode on the nightside.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Review
Astronomy & Astrophysics
Tomoki Kimura, Yuka Fujii, Hajime Kita, Fuminori Tsuchiya, Hideo Sagawa
Summary: Low-frequency radio emissions from bodies in our solar system have significant implications for understanding their magnetosphere, atmosphere, surface, and interior. This review highlights key questions regarding the dynamics and evolution of these bodies, and explores the feasibility of using the Square Kilometre Array (SKA) for future observations.
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
(2023)
Article
Astronomy & Astrophysics
L. Chen, K. Shiokawa, Y. Miyoshi, S. Oyama, C-W Jun, Y. Ogawa, K. Hosokawa, Y. Inaba, Y. Kazama, S. Y. Wang, S. W. Y. Tam, T. F. Chang, B. J. Wang, K. Asamura, S. Kasahara, S. Yokota, T. Hori, K. Keika, Y. Kasaba, A. Kumamoto, F. Tsuchiya, M. Shoji, Y. Kasahara, A. Matsuoka, I Shinohara, S. Imajo, S. Nakamura, M. Kitahara
Summary: In this study, the source plasma and field variations of a substorm brightening aurora in the inner magnetosphere were comprehensively observed. The observations showed that the brightening arc displayed east-west structures, synchronized with the appearance of bi-directional electrons detected by a satellite. The magnetic and electric field data exhibited characteristic fluctuations and earthward Poynting flux, suggesting the possibility of a ballooning instability.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
H. T. Smith, R. Koga, F. Tsuchiya, V. J. Dols
Summary: Io is an important source of particles for Jupiter's magnetosphere, and the JAXA Hisaki mission provides valuable observations of Io's neutral particle populations. The mission's UV neutral oxygen line of sight observations allow for direct observation of the neutral tori and provide insights into the sources and mechanisms from Io. However, 3-D modeling is necessary to interpret the complex observational geometries.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Geochemistry & Geophysics
A. V. Rubtsov, M. Nose, A. Matsuoka, Y. Kasahara, A. Kumamoto, F. Tsuchiya, I. Shinohara, Y. Miyoshi
Summary: The radial distribution of ion mass density in the Earth's magnetosphere can differ from that of electrons when there is a localized enhancement of heavy ion flux, such as an oxygen torus. This difference is crucial for the study of ultra-low-frequency (ULF) waves, which rely on the Alfven velocity and mass density. One important consequence is the shift in the location of the plasmapause, which is considered as the resonator and generation area for ULF waves. In this study, we identified that a factor of 1.65 or more increase in the Alfven velocity within a radial distance of 0.5 RE corresponds to the classic definition of plasmapause, where the electron density drops by a factor of 5 or more within the same radial distance. This finding allows us to confidently use the Alfven velocity to detect the plasmapause even when heavier ions are included and a direct comparison with electron density is not possible.
JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS
(2023)
Article
Environmental Sciences
Desy Purnami Singgih Putri, Yoshiya Kasahara, Mamoru Ota, Shoya Matsuda, Fuminori Tsuchiya, Atsushi Kumamoto, Ayako Matsuoka, Yoshizumi Miyoshi
Summary: This paper proposes a technique to correct plasmaspheric electron density profiles using ray tracing and dispersion analyses of lightning whistlers. The Global Core Plasma Model and the International Reference Ionosphere are used as reference density profiles, and modifications are made to satisfy the dispersion characteristics of observed whistlers. The method is applied to two lightning whistler events and the effect of density modification on ray path delay time is analyzed.
Article
Astronomy & Astrophysics
D. P. Hartley, G. S. Cunningham, J. -f. Ripoll, D. M. Malaspina, Y. Kasahara, Y. Miyoshi, S. Matsuda, S. Nakamura, F. Tsuchiya, M. Kitahara, A. Kumamoto, I. Shinohara, A. Matsuoka
Summary: A new empirical density model is developed for the inner zone between 1 L < 3 by using plasma densities inferred from the upper hybrid resonance on Arase and hiss-inferred density values from Van Allen Probes. The model includes dependencies on L, magnetic latitude, and magnetic local time (MLT), and can provide density values in areas outside the validity region of many previous models, making it a useful resource for accurately determining diffusion coefficients and predicting electron dynamics and their lifetimes in the inner radiation belt.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Shin Sugo, Satoshi Kasahara, Yoshizumi Miyoshi, Yuto Katoh, Kunihiro Keika, Shoichiro Yokota, Tomoaki Hori, Yoshiya Kasahara, Shoya Matsuda, Ayako Matsuoka, Iku Shinohara, Fuminori Tsuchiya, Atsushi Kumamoto, Satoko Nakamura, Masahiro Kitahara
Summary: Plasmaspheric hiss waves play a crucial role in electron precipitation and the formation of the slot region in the Earth's radiation belt. Previous studies have shown that the intensity of whistler-mode waves and electron precipitation is influenced by electron density and background magnetic field strength. However, direct evidence of strong pitch angle scattering by hiss waves inside the plasmasphere has been lacking, and the simultaneous investigation of density and magnetic field structures with hiss wave enhancement and electron precipitation has not been conducted. Our study provides direct observations of the importance of electron density and its spatial structure in electron precipitation, and the occurrence of strong scattering up to a magnetic latitude of about 15°.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Zhiyang Xia, Lunjin Chen, Wenyao Gu, Richard B. Horne, Yoshizumi Miyoshi, Yoshiya Kasahara, Atsushi Kumamoto, Fuminori Tsuchiya, Satoko Nakamura, Masahiro Kitahara, Iku Shinohara
Summary: In this study, 3 years of data from the ERG/Arase satellite was used to analyze the meridional distribution of wave power from VLF ground transmitters in the inner magnetosphere. It was found that the intensity of NWC transmitter signals decreases as they propagate from the southern to the equatorial region, and then increases as they propagate to the northern region. Similar results were observed from Van Allen Probes' data within a narrower latitude range. A ray-tracing simulation of the transmitter emission propagation reproduced similar meridional wave power distribution. Similar latitudinal dependence was also found for NAA, NLK, and NLM transmitters.
FRONTIERS IN ASTRONOMY AND SPACE SCIENCES
(2023)
Article
Astronomy & Astrophysics
Lorenz Roth, H. Todd Smith, Kazuo Yoshioka, Tracy M. Becker, Aljona Bloecker, Nathaniel J. Cunningham, Nickolay Ivchenko, Kurt D. Retherford, Joachim Saur, Michael Velez, Fuminori Tsuchiya
Summary: In situ plasma measurements and remote mapping of energetic neutral atoms around Jupiter provide indirect evidence of enhanced neutral gas near the orbit of moon Europa. Observations by the Cosmic Origins Spectrograph (COS) of the Hubble Space Telescope (HST) from 2020 to 2021 do not detect any neutral gas emissions. Comparison with modeled emissions supports the previous findings that the torus is dilute and primarily consists of molecular hydrogen. Detection of sulfur ion emissions is consistent with emissions from the extended Io torus.
PLANETARY SCIENCE JOURNAL
(2023)
Article
Astronomy & Astrophysics
Asuka Hirai, Fuminori Tsuchiya, Takahiro Obara, Yuto Katoh, Yoshizumi Miyoshi, Kazuo Shiokawa, Yasumasa Kasaba, Hiroaki Misawa, Chae-Woo Jun, Satoshi Kurita, Martin G. G. Connors, Aaron T. T. Hendry, Atsuki Shinbori, Yuichi Otsuka, Takuya Tsugawa, Michi Nishioka, Septi Perwitasari, Jerry W. W. Manweiler
Summary: By analyzing ground and satellite observations of EMIC waves, researchers found that the increased frequency of intervals of pulsations of diminishing periods (IPDPs) is caused by an inward shift of the EMIC wave source region, which is influenced by the enhanced convection electric field. This inward shift allows EMIC waves to scatter relativistic electrons over a wide range of radial distances during IPDP events. The study also suggests a possible contribution of EMIC waves to outer radiation belt loss during the main phase of geomagnetic storms.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Shinnosuke Satoh, Fuminori Tsuchiya, Shotaro Sakai, Yasumasa Kasaba, Rikuto Yasuda, Tomoki Kimura
Summary: Observations from the Hubble Space Telescope reveal an asymmetry in the morphology of the oxygen O-I] 135.6 nm emissions in Europa's atmosphere, which changes with the moon's position relative to Jupiter's magnetospheric plasma sheet. This study uses a test particle simulation to evaluate the cause of this north-south asymmetry and successfully reproduces it with the idea of a deceleration effect of the magnetospheric flux tube. However, additional model scenarios are needed to fully explain the observed brightness ratio.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
A. V. Rubtsov, M. Nose, A. Matsuoka, Y. Kasahara, A. Kumamoto, F. Tsuchiya, I. Shinohara, Y. Miyoshi
Summary: Magnetic storms and substorms cause global disturbances in the Earth's magnetosphere. Plasma clouds injected from the magnetotail during storm or substorm drift around the Earth and generate ultra-low frequency (ULF) waves via various mechanisms. The plasmasphere and its boundary, plasmapause, are special regions for ULF waves to interact with charged particles.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)