Like Earth, Jupiters magnetic field channels electrically charged particles into its environment, resulting in the formation of brilliant aurorae near its poles. Of particular interest are patches of emission that stem from even closer to the poles than the primary aurorae, a function that appears far stronger at Jupiter than at Earth or Saturn.
The authors carry out one-dimensional magnetohydrodynamic modeling to track the development of private magnetic field lines in the vicinity of Jupiters pole. The authors suggest downward traveling energetic electrons may be the source of the swirl regions in Jupiters polar aurorae.
This composite image reveals the area of Jupiters northern aurorae, as seen by the Hubble Space Telescope. Strong auroral activity occurs extremely near the pole, a feature distinct in the solar system to Jupiter. Credit: NASA, ESA, and J. Nichols, University of Leicester
Magnetic reconnection events less than 2 Jovian radii above the planets cloud tops might describe why Juno has yet to observe a source for Jupiters polar aurore.
Like Earth, Jupiters electromagnetic field channels electrically charged particles into its atmosphere, leading to the development of dazzling aurorae near its poles. Nevertheless, the brightness and range of Jupiters auroral emissions go beyond those generated on our planet. Of specific interest are patches of emission that originate from even closer to the poles than the main aurorae, a function that appears far more powerful at Jupiter than at Earth or Saturn.
Emission in the polar region can be fleeting, lasting minutes or sometimes just seconds. The polar auroral location can be additional divided into three morphologies: “dark” regions of minimal emission, “active” regions of vigorous emission, and, at the greatest latitudes, “swirl” regions of rough emission.
NASAs Juno spacecraft has actually spotted down particle fluxes that can account for the main emission. No such flux has actually been discovered that could account for the bulk of the polar emissions, particularly those from the swirl areas. Masters et al. propose a system that would not yet have been observed by Juno: magnetic reconnection occurring not far above the Jovian cloud tops.
The authors carry out one-dimensional magnetohydrodynamic modeling to track the development of individual electromagnetic field lines in the vicinity of Jupiters pole. They model the area beginning at the top of the planets atmosphere and extending 2 Jovian radii from that point. This area lies entirely listed below any extant spacecraft observations.
Waves moving through the plasma go into the model domain from above, created by interactions further out in the worlds magnetosphere. The propagation of these waves has the result of deflecting the idealized electromagnetic field lines from a perfectly vertical position. This is a little effect, on the order of 0.01 °, however it may suffice to kick-start magnetic reconnection occasions between neighboring field lines.
Throughout reconnection, adjacent field lines break and reform in a more energetically favorable configuration. This procedure releases energy saved within the field, which is carried away by the velocity of nearby charged particles. The authors recommend down traveling energetic electrons might be the source of the swirl regions in Jupiters polar aurorae.
Finally, the authors recommend that this result isnt important at Earth or Saturn since of their weaker magnetic fields. Jupiters field is more than an order of magnitude stronger, and the reconnection rate increases by approximately the square of that worth. Therefore, Jupiter has strong polar aurorae, whereas Earth and Saturn do not.
Recommendation: “Magnetic Reconnection Near the Planet as a Possible Driver of Jupiters Mysterious Polar Auroras” by A. Masters, W. R. Dunn, T. S. Stallard, H. Manners and J. Stawarz, 14 July 2021, Journal of Geophysical Research: Space Physics.DOI: 10.1029/ 2021JA029544.