Extreme Ultraviolet Explorer Satellite Observation of Jupiter's Io Plasma Torus
Abstract
We present the first Extreme Ultraviolet Explorer (EUVE) satellite observation of the Jupiter system, obtained during the 2 day period 1993 March 30 through April 1, which shows a rich emission-line spectrum from the Io plasma torus spanning wavelengths 370 to 735 A. The emission features correspond primarily to known multiplets of oxygen and sulfur ions, but a blended feature near 372 A is a plausible Na II transition. The summed detected energy flux of (7.2 +/- 0.2) x 10-11 ergs/sq cm(s) corresponds to a radiated power of approximately equal to 4 x 1011 W in this spectral range. All ansa emissions show a distinct dawn-dusk brightness asymmetry and the measured dusk/dawn ratio of the bright S III lambda-680 feature is 2.3 +/- 0.3, significantly larger than the ratio measured by the Voyager spacecraft ultraviolet (UV) instruments. A preliminary estimate of ion partitioning indicates that the oxygen/sulfur ion ratio is approximately equal to 2, compared to the value approximately equal to 1.3 measured by Voyager, and that (Na(+))/(e) greater than 0.01.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1994
- DOI:
- 10.1086/187337
- Bibcode:
- 1994ApJ...426L..51H
- Keywords:
-
- Io;
- Jupiter (Planet);
- Space Plasmas;
- Spaceborne Astronomy;
- Toroidal Plasmas;
- Toruses;
- Ultraviolet Astronomy;
- Ultraviolet Spectra;
- Astronomical Spectroscopy;
- Asymmetry;
- Emission Spectra;
- Extreme Ultraviolet Explorer Satellite;
- Line Spectra;
- Spectrographs;
- Ultraviolet Spectroscopy;
- Astronomy;
- LINE: IDENTIFICATION;
- PLANETS AND SATELLITES: INDIVIDUAL IO;
- PLANETS AND SATELLITES: INDIVIDUAL JUPITER;
- PLASMAS;
- ULTRAVIOLET: SOLAR SYSTEM