Jupiter possesses an exceptionally strong magnetic field, and within its magnetosphere lies a vast distribution of plasma released from its volcanically active moon, Io. This plasma forms a structure known as the Io plasma torus, from which narrowband kilometric radiation (nKOM) is emitted.
The objective of my research is to investigate the long-term variations in the occurrence frequency and intensity of nKOM emissions, in order to clarify their relationship with magnetospheric dynamics such as injection phenomena within Jupiter’s magnetosphere.

We focus on the volcanically active Io and the icy moon Europa. Sulfur and oxygen ions generated from Io spread to Europa’s orbit as a doughnut-shaped Io plasma torus. However, time and spatial continuity of plasma parameters at Europa’s orbit has rarely been investigated because of the limited observations. This study aims to estimate the electron density, electron temperature, and ion composition in Io plasma torus from Io’s orbit to Europa’s orbit using Hisaki satellite data. As a result, the sulfur and oxygen ion emission lines were successfully identified at Europa’s orbit. We will work on how the plasma density and ion composition at Europa’s orbit changed in response to Io’s volcanic activity occurred in late January 2015.

Jupiter’s polar regions exhibit auroral emissions with complex structures. The “footprint aurora” associated with Europa is a signature of the plasma environment around Europa. Using the observations of the footprint aurora made by the Hubble Space Telescope, I detected temporal variations in the plasma mass density and temperature around Europa. Currently, I am continuing my research using the high spatial resolution data obtained by the Juno spacecraft. A detailed investigation of the footprint aurora will lead to a deeper understanding of the plasma environment surrounding Europa.

Jupiter’s synchrotron radiation (JSR) is emitted from the high-energy electrons trapped in the Jupiter’s radiation belts. Its intensity and frequency depend on electron energy, electron number density, and magnetic field strength.

We are observing the JSR with several telescopes, including the Giant Metrewave Radio Telescope (GMRT) in India, and analyzing the data to estimate the spatial structure and energy spectrum of electrons in Jupiter’s radiation belts.