Dynamic infrared aurora on Jupiter
2025-05-12
Auroral emissions are an important diagnostic for a planet’s magnetosphere and upper atmosphere. At the outer planets, the characteristics of emission from the triatomic hydrogen ion $${{\rm{H}}}_{3}^{+}$$ H 3 + are key to understanding the auroral energy budget. We present James Webb Space Telescope observations of Jupiter’s infrared auroral $${{\rm{H}}}_{3}^{+}$$ H 3 + emission, exhibiting variability on timescales down to seconds. Together with simultaneous Hubble Space Telescope ultraviolet observations, these results imply an auroral $${{\rm{H}}}_{3}^{+}$$ H 3 + lifetime of 150 s, and that $${{\rm{H}}}_{3}^{+}$$ H 3 + cannot efficiently radiate heat deposited by bursty auroral precipitation. However, $${{\rm{H}}}_{3}^{+}$$ H 3 + radiation is particularly efficient in a dusk active region, which has no significant ultraviolet counterpart. The cause of such emission is unclear. We also present observations of rapid eastward-travelling auroral pulses in the dawn side auroral region and pulsations that propagate rapidly along the Io footprint tail. Together, these observations open a diagnostic window for the jovian magnetosphere and ionosphere.