Other
Scientific paper
Mar 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994jgr....99.4143h&link_type=abstract
Journal of Geophysical Research (ISSN 0148-0227), vol. 99, no. A3, p. 4143-4160
Other
19
Auroras, Convection, Magnetic Field Configurations, Particle Precipitation, Planetary Magnetospheres, Ultraviolet Emission, Uranus (Planet), Uranus Atmosphere, Airglow, Hydrogen, Interstellar Matter, Ultraviolet Spectrometers, Voyager 2 Spacecraft, Whistlers, Uranus, Auroras, Magnetosphere, Airglow, Emissions, Voyager 2 Mission, Spacecraft Observations, Uvs Instrument, Analysis, Intensity, Origin, Magnetic Pole, Magnetic Properties, Position (Location), Convection, Source, Energy, Excitation, Calculations,
Scientific paper
About 32 h of Voyager Ultraviolet Spectrometer (UVS) observations of Uranus H2 band airglow emission (875 less than or equal to lambda less than or equal to 1115 A) have been analyzed using the singular value decomposition (SVD) approach to inversion, producing an intensity map showing aurora at both magnetic poles. An H Lyman alpha aurora may also be present but is difficult to separate from scattered solar and local interstellar medium components. SVD analysis of variance shows that the intensity estimate is significantly larger than the error estimate over both Uranographic poles and part of the equatorial region, fortuitously including both magnetic polar regions. The Goddard Space Flight Center Q3 magnetic field model correctly predicts that the aurora should be larger in area and emit more power at the weaker N magnetic pole than at the stronger S magnetic pole. However, the auroral emissions are quite localized in magnetic longitude and so do not form complete auroral ovals. The brightest auroral emission at each magnetic pole is confined to a range of approximately 90 deg of magnetic longitude centered on the magnetotail direction, at moderate magnetic L parameter (5 less than or equal to L less than or equal to 10), but some emission at each pole is distributed over a range of more than 180 deg of longitude. The magnetic longitudes of the aurora are completely inconsistent with the 'windshield wiper' effect for either ions or electrons, indicating that some other effect, such as rapid depletion of the population of precipitating particles of highly localized strong pitch-angle diffusion, may be acting to localize emission. The low apparent L of the precipitating particles indicates that their energies may be less than or equal to 10 keV. Hence magnetospheric convection is likely to be important, and thus particles exciting the aurora may not remain on constant L shells. The precipitating particles may be a relatively low-energy population at high L that is heated to aurora-exciting energy by adiabatic compression during convection to low L. We estimate that the total auroral power output at H Lyman alpha and shorter wavelengths is about 3 x 109 to 7 x 109 W, requiring about 10 times that much power for excitation.
Herbert Fritz
Sandel Bill R.
No associations
LandOfFree
The Uranian aurora and its relationship to the magnetosphere does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Uranian aurora and its relationship to the magnetosphere, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Uranian aurora and its relationship to the magnetosphere will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1872034