Magnetic Hole and Its Resultant Electron Pitch‐Angle Distribution at Jupiter.

Magnetic hole (MH), sometimes referred to as magnetic bottle, exhibits strong magnetic fields at its neck but weak magnetic fields at its belly. Such structure has been widely reported in the solar wind and the Earth's magnetosphere, but has not been reported at Jupiter. Here, for the first time, we report two MHs in the Jupiter's magnetosphere by utilizing measurements of the Juno mission, with one existing in the dawn side and the other existing in the dusk side. We find that the electron pitch‐angle distribution inside the MHs can be either cigar‐type or pancake‐type. The cigar‐type distribution probably appears at the belly of the MH, whereas the pancake‐type distribution probably appears at the neck. Our analyses of the depression of magnetic fields inside the MHs support such a conjunction. These results have advanced our understanding of the transient structure and its related electron dynamics in the giant planets' magnetosphere. Plain Language Summary: Examining the electron pitch‐angle distribution (PAD) can help us better understand the electron dynamics in planetary magnetosphere. Up to now, there has been no report of magnetic holes (MHs) at Jupiter and thus the electron dynamics in such place is unknown. Here using the Juno measurements, we for the first time report two MHs in the Jupiter's magnetosphere. We find the PA distribution of suprathermal electrons inside the MHs can be either cigar type or pancake type, and further explain their formation processes by using a magnetic bottle model. Our study is very useful to understand electron dynamics in Jupiter's magnetosphere. Key Points: For the first time, we report magnetic holes (MHs) in the Jupiter's magnetosphereWe found both cigar and pancake distribution of electrons inside magnetic holesUsing a magnetic bottle model, we reasonably explain the formation of these two distributions and provide observation evidence [ABSTRACT FROM AUTHOR]