Plasma wave observations from Juno spacecraft at the Jovian bow shock

Abstract

Recent observations of Jupiter’s bow shock have provided new insights into the energy dissipation mechanisms associated with bow shocks of outer planets. At greater distances from the Sun, the typically increasing super-Alfvénic nature of the solar wind leads to higher-energy bow shocks with enhanced dissipation requirements. Research on Earth’s bow shock suggests that plasma waves (e.g., ion-acoustic waves, waves driven by the electron cyclotron drift instability, electrostatic solitary waves, and whistler mode waves) play a critical role in converting solar wind bulk kinetic energy into thermal energy. However, the lack of high-resolution plasma wave data, which is essential for detecting these waves, has previously hindered their identification at the outer planets. Here we demonstrate, based on two case studies, that similar waves also exist at Jupiter’s bow shock. But, unlike their terrestrial counterparts, Ion-acoustic waves at Jupiter may display harmonic structures, indicating possible particle trapping, and intense electron cyclotron drift instability may occur to accommodate the shock’s intensity. Magnetic field measurements suggest possible shock reformation. Plasma waves mediate conversion of solar wind kinetic energy into thermal energy at bow shocks. Here, the authors show waves at Jupiter’s bow shock resemble those at Earth but exhibit distinct harmonic structures, enhancing heating.