2025-11-13

PPARCセミナー (2025/11/14)

(1)

[Name]

Hiroaki Misawa

[Title]

Polarization characteristics of Jupiter’s hectometric radio emission (HOM)

[Abstract]

It has been known that Jupiter shows somewhat rare characteristic in its polarization (Pol.) of non-thermal radio emission among low frequency radio stars; i.e., highly elliptical Pol. of the decametric wave length radio emission (DAM) which is the most intense Jupiter’s radio emission. On the other hand, the Pol. characteristic of Jupiter’s longer wave length ranges, even another intense radio emission component in the hectometer wave length range (HOM), is poorly known due to limited Pol. observations. Therefore investigations of the Pol. characteristic is thought to be one of important observation themes, particularly in the on-going JUICE (JUpiter ICy moons Explorer) mission as the two points; one is as it would give clues to the origin of the long wave radio emissions and another one is as it may provide information as a remote sensing tool on plasma environment along their propagation paths of, for example, Io plasma torus and ionospheres of icy moons with the Faraday rotation analysis.
In order to evaluate a possibility of plasma environment exploration using the Pol. characteristics of Jupiter’s radio emissions with the JUICE mission, we have investigated Pol. characteristics of HOM using the data by High Frequency Analyzer (HFA) which is a subsystem of Plasma Wave Experiment (PWE) onboard the ERG(Arase) spacecraft. 　　
　Preliminary analyses are performed for 11 HOM events with high S/N obtained for Nov. 2017 ? Nov. 2021 and show that (1)RHCP(Right Handed Circular Pol.) HOMs are more circular than LHCP (Left Handed Circular Pol.) HOMs and (2)Most of ‘normal (non QP(Quasi-Periodic))’ HOMs are RHCP, while QP-HOMs are LHCP, suggesting normal/QP-HOMs would be originated from the northern/southern hemisphere.