科研之友
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摘要
Recent studies based on Hubble Space Telescope (HST) data reported the presence of transient polar dawn spots in the Jovian auroral region and interpreted them as signatures of internally driven magnetic reconnection in the Jovian magnetotail. Even though an association of the polar dawn spots with the reconnection process has been suggested, it has not been yet investigated which part of the process and what mechanism powers these auroral emissions. In the present study, we examine the scenario that the auroral spots are triggered by the inward moving flow bursts released during magnetic reconnection at Jupiter. We base our analysis on a model adapted from the terrestrial case, according to which moving plasma flow burst is coupled with the ionosphere by field-aligned currents, giving rise to auroral emissions. We estimate the upward field-aligned current at the flank of the flow bursts, using in-situ magnetic field measurements and we derive the auroral emitted power. We statistically study the observed emitted power of the polar dawn spots, based on HST data from 1998 to 2007, and we compare it with the emitted power derived according to the proposed scenario. Apart from the emitted power, other properties of the polar dawn spots such as their location, periodicity, duty cycle and multiplicity suggest that they are associated with the inward moving flow bursts released during magnetic reconnection in Jupiter's tail.
- 出版日期2010-7-17
