Pulsation Characteristics of Jovian Infrared Northern Aurora Observed by the Subaru IRCS with Adaptive Optics

Abstract

We report narrow band-filtered imaging observations of the Jovian H3+ 3.4-μm emission using the IRCS (infrared camera and spectrograph) on the Subaru telescope taken on 25 May 2016. Approximately 1 hr of data was taken at intervals of 45–110 s, with high spatial resolution (~0.2 arcsec) using adaptive optics. In the northern polar region, we found bright patch-like emissions on the poleward side of the main oval. One of them had a pulsation period of ~10 min. We utilized an H3+ emission model to investigate the response time of the H3+ emission to abrupt and periodic variations of the precipitating electron flux. The model showed that the H3+ emission could pulsate with this timescale due to a modulated flux of the precipitating electrons in the kilo-electron-volt to tens of kilo-electron-volt energy range.