Origin of the main auroral oval in Jupiter's coupled magnetosphere–ionosphere system

摘要: Abstract We show that the principal features of main auroral oval in jovian system are consistent with an origin magnetosphere–ionosphere coupling currents associated departure plasma from rigid corotation middle magnetosphere, specifically inner region field-aligned current directed upwards ionosphere to magnetosphere. The we refer include its location, continuity local time, width, and precipitating particle energy flux luminosity. A simple empirical model field flow magnetosphere is used estimate flowing into out equatorial sheet breakdown corotation. models indicate flows outwards through most Mapped ionosphere, upward density order ∼1 μA m −2 , confined circumpolar annular rings around each pole latitudinal width ∼1° (∼1000 km ), centred near ∼16° dipole latitude. carried principally by downward-precipitating magnetospheric electrons tenuous hot which extends outside cooler denser high latitudes. For reasonable observed values electron parameters it found such require existence voltages ∼100 kV . primaries thus keV electrons, deep penetration atmosphere low-altitude auroras, as observed. peak ionospheric accelerated ∼0.1– 1 W sufficient drive a UV aurora 1–10 MR at ∼20% conversion efficiency. In addition, produce current, acceleration must extend altitude typically above ∼3–4RJ. spatially extended energetic beams so formed suggested form source free for non-Io-related radio emissions. An important implication auroras emissions will respond dynamic pressure solar wind, sense anticorrelation.