Diffuse Jovian aurora influenced by plasma injection from IO

Journal Article · Wed Aug 01 04:00:00 EDT 1979 · Geophys. Res. Lett.; (United States)

DOI:https://doi.org/10.1029/GL006i008p00649· OSTI ID:5939281

Thorne, R M; Tsurutani, B T

Cyclotron resonant instability of Jovian energetic electrons is dramatically enhanced as a consequence of the lower resonant electron energy (E/sub res/proportionalB/sup 2//8..pi..N) within the equatorial high density plasma torus surrounding the orbit of Io. This mechanism accounts adequately for the continuous broad band whistler mode waves observed within the Io torus on Voyager I. The higher energy resonant electrons (approx.100 keV to 1 MeV) can be scattered by the observed low frequency waves (< or approx. =1 kHz) at a rate as high as 10 percent of the limit attainable under strong pitch-angle diffusion; the corresponding energetic electron lifetimes are comparable to a day. This is much shorter than any realistic estimates for radial diffusion transport near Io. Thus an efficient local acceleration process is required to continually replenish the precipitating relativistic electrons. Concomitant energy deposition into the Jovian atmosphere is estimated to be approx.5 to 15 ergs cm/sup -2/ sec/sup -1/ over a broad invariant latitude range mapping from the Io plasma torus (65/sup 0/< or approx. =..lambda..< or approx. =75/sup 0/). This intense precipitation should both provide a dominant source of middle atmospheric ionization and excite a continuous band of diffuse auroral emission. In the absence of significant extinction, H Ly..cap alpha.. intensity is estimated to be 30 to 100 kR in approximate agreement with the Voyager Extreme Ultraviolet observations. Total power dissipation over the diffuse auroral zone should be at least 10/sup 13/ watts. Because the cyclotron resonant scattering process is strongly influenced by the ambient equatorial thermal plasma density we suggest that the diffuse Jovian aurora should be influenced by the variable volcanic activity on Io which is thought to be an important source of plasma.

• Research Organization: Dept. of Atmospheric Sciences, University of California, Los Angeles, 90024
• OSTI ID: 5939281
• Journal Information: Geophys. Res. Lett.; (United States), Journal Name: Geophys. Res. Lett.; (United States) Vol. 6:8; ISSN GPRLA
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics &amp; Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
CHARGED-PARTICLE PRECIPITATION
DIFFUSION
ELECTROMAGNETIC RADIATION
ELECTRON PRECIPITATION
EXTREME ULTRAVIOLET RADIATION
JUPITER PLANET
PLANETARY IONOSPHERES
PLANETS
PLASMA DENSITY
RADIATIONS
SATELLITES
SPACE VEHICLES
ULTRAVIOLET RADIATION
VOYAGER SPACE PROBES