Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Site Tools

  • AAAS
  • Subscribe
  • Feedback

Site Search

Search Advanced

Science 23 November 1979:
Vol. 206. no. 4421, pp. 977 - 984
DOI: 10.1126/science.206.4421.977
Prev | Table of Contents | Next

Articles

Hot Plasma Environment at Jupiter: Voyager 2 Results

S. M. KRIMIGIS 1, T. P. ARMSTRONG 2, W. I. AXFORD 3, C. O. BOSTROM 4, C. Y. FAN 5, G. GLOECKLER 6, L. J. LANZEROTTI 7, E. P. KEATH 4, R. D. ZWICKL 4, J. F. CARBARY 4, and D. C. HAMILTON 8

1 Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland 20810
2 Department of Physics and Astronomy, University of Kansas, Lawrence 66044
3 Max-Planck Institute for Aeronomy, D-3411 Katlenburg-Lindau 3, West Germany
4 Applied Physics Laboratory, Johns Hopkins University
5 Department of Physics, University of Arizona, Tucson 85721
6 Department of Physics and Astronomy, University of Maryland, College Park 20742
7 Bell Telephone Laboratories, Murray Hill, New Jersey 07974
8 Department of Physics and Astronomy, University of Maryland

Measurements of the hot (electron and ion energies ge20 and ge 28 kiloelectron volts, respectively) plasma environment at Jupiter by the low-energy charged particle (LECP) instrument on Voyager 2 have revealed several new and unusual aspects of the Jovian magnetosphere. The magnetosphere is populated from its outer edge into a distance of at least sim 30 Jupiter radii (RJ) by a hot (3 x 108 to 5 x 108 K) multicomponent plasma consisting primarily of hydrogen, oxygen, and sulfur ions. Outside sim 30 RJ the hot plasma exhibits ion densities from sim 10–1 to sim 10–6 per cubic centimeter and energy densities from sim 10–8 to 10–13 erg per cubic centimeter, suggesting a high beta plasma throughout the region. The plasma is flowing in the corotation direction to the edge of the magnetosphere on the dayside, where it is confined by solar wind pressure, and to a distance of sim 140 to 160 RJ on the nightside at sim 0300 local time. Beyond sim 150 RJ the hot plasma flow changes into a "magnetospheric wind" blowing away from Jupiter at an angle of sim 20° west of the sun-Jupiter line, characterized by a temperature of sim 3 x 108 K (26 kiloelectron volts), velocities ranging from sim 300 to > 1000 kilometers per second, and composition similar to that observed in the inner magnetosphere. The radial profiles of the ratios of oxygen to helium and sulfur to helium (le 1 million electron volts per nucleon) monotonically increase toward periapsis, while the carbon to helium ratio stays relatively constant; a significant amount of sodium (Na/O sim 0.05) has also been identified. The hydrogen to helium ratio ranges from sim 20 just outside the magnetosphere to values up to sim 300 inside; the modulation of this ratio suggests a discontinuity in the particle population at sim 50 to 60 RJ. Large fluctuations in energetic particle intensities were observed on the inbound trajectory as the spacecraft approached Ganymede, some of which suggest the presence of a "wake." Five-and 10-hour periodicities were observed in the magnetosphere. Calculations of plasma flow velocities with the use of Compton-Getting formalism imply that plasma is mostly corotating to large radial distances from the planet. Thus the Jovian magnetosphere is confined by a plasma boundary (as was implied by the model of Brice and Ioannidis) rather than a conventional magnetopause. Inside the plasma boundary there exists a discontinuity at sim 50 to 60 RJ we have named the region inside this discontinuity the "inner plasmasphere."

Submitted on September 19, 1979


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
The Hot Plasma Environment at Jupiter: Ulysses Results.
L. J. Lanzerotti, T. P. Armstrong, R. E. Gold, K. A. Anderson, S. M. Krimigis, R. P. Lin, M. Pick, E. C. Roelof, E. T. Sarris, G. M. Simnett, et al. (1992)
Science 257, 1518-1524
   Abstract »    PDF »
An Overview of Energetic Particle Measurements in the Jovian Magnetosphere with the EPAC Sensor on Ulysses.
E. Keppler, J. B. Blake, M. Franz, A. Korth, N. Krupp, J. J. Quenby, M. Witte, and J. Woch (1992)
Science 257, 1553-1557
   Abstract »    PDF »
Low-Energy Hot Plasma and Particles in Saturn's Magnetosphere.
S. M. KRIMIGIS, T. P. ARMSTRONG, W. I. AXFORD, C. O. BOSTROM, G. GLOECKLER, E. P. KEATH, L. J. LANZEROTTI, J. F. CARBARY, D. C. HAMILTON, and E. C. ROELOF (1982)
Science 215, 571-577
   Abstract »    PDF »
Erosion of Galilean Satellite Surfaces by Jovian Magnetosphere Particles.
R. E. Johnson, R. E. JOHNSON, L. J. LANZEROTTI, W. L. BROWN, and T. P. ARMSTRONG (1981)
Science 212, 1027-1030
   Abstract »    PDF »
Plasma Observations Near Saturn: Initial Results from Voyager 1.
H. S. BRIDGE, J. W. BELCHER, A. J. LAZARUS, S. OLBERT, J. D. SULLIVAN, F. BAGENAL, P. R. Gazis, R. E. HARTLE, K. W. OGILVIE, J. D. SCUDDER, et al. (1981)
Science 212, 217-224
   Abstract »    PDF »
Preliminary Results on the Plasma Environment of Saturn from the Pioneer 11 Plasma Analyzer Experiment.
J. H. WOLFE, J. D. MIHALOV, H. R. COLLARD, D. D. MCKIBBIN, L. A. FRANK, and D. S. INTRILIGATOR (1980)
Science 207, 403-407
   Abstract »    PDF »
Voyager 2: Energetic Ions and Electrons in the Jovian Magnetosphere.
R. E. VOGT, A. C. CUMMINGS, T. L. GARRARD, N. GEHRELS, E. C. STONE, J. H. TRAINOR, A. W. SCHARDT, T. F. CONLON, and F. B. MCDONALD (1979)
Science 206, 984-987
   Abstract »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)