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Science 18 April 1986:
Vol. 232. no. 4748, pp. 356 - 361
DOI: 10.1126/science.232.4748.356
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Articles

Comet Giacobini-Zinner: Plasma Description

S. J. BAME 1, R. C. ANDERSON 1, J. R. ASBRIDGE 1, D. N. BAKER 1, W. C. FELDMAN 1, S. A. FUSELIER 1, J. T. GOSLING 1, D. J. MCCOMAS 1, M. F. THOMSEN 1, D. T. YOUNG 1, and R. D. ZWICKL 1

1 University of California, Los Alamos National Laboratory, Los Alamos, NM 87545.

A strong interaction between the solar wind and comet Giacobini-Zinner was observed oh 11 September 1985 with the Los Alamos plasma electron experiment on the International Cometary Explorer (ICE) spacecraft. As ICE approached an intercept point 7800 kilometers behind the nucleus from the south and receded to the north, upstream phenomena due to the comet were observed. Periods of enhanced electron heat flux from the comet as well as almost continuous electron density fluctuations were measured. These effects are related to the strong electron heating observed in the cometary interaction region and to cometary ion pickup by the solar wind, respectively. No evidence for a conventional bow shock was found as ICE entered and exited the regions of strongest interaction of the solar wind with the cometary environment. The outer extent of this strong interaction zone was a transition region in which the solar wind plasma was heated, compressed, and slowed. Inside the inner boundary of the transition region was a sheath that enclosed a cold intermediate coma. In the transition region and sheath, small-scale enhancements in density were observed. These density spikes may be due to an instability associated with cometary ion pickup or to the passage of ICE through cometary ray structures. In the center of the cold intermediate coma a narrow, high-density core of plasma, presumably the developing plasma tail was found. In some ways this tail can be compared to the plasma sheet in Earth's magnetotail and to the current sheet in the tail at Venus. This type of configuration is expected in the double-lobe magnetic topology detected at the comet, possibly caused by the theoretically expected draping of the interplanetary magnetic field around its ionosphere.

Submitted on November 20, 1986
Accepted on January 31, 1986


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Jupiter's Magnetosphere: Plasma Description from the Ulysses Flyby.
S. J. Bame, B. L. Barraclough, W. C. Feldman, G. R. Gisler, J. T. Gosling, D. J. McComas, J. L. Phillips, M. F. Thomsen, B. E. Goldstein, and M. Neugebauer (1992)
Science 257, 1539-1543
   Abstract »    PDF »
The International Cometary Explorer Mission to Comet Giacobini-Zinner.
T. T. VON ROSENVINGE, J. C. BRANDT, and R. W. FARQUHAR (1986)
Science 232, 353-356
   Abstract »    PDF »
Observations of Energetic Ions from Comet Giacobini-Zinner.
R. J. HYNDS, S. W. H. COWLEY, T. R. SANDERSON, K.-P. WENZEL, and J. J. VAN ROOIJEN (1986)
Science 232, 361-365
   Abstract »    PDF »
Comet Giacobini-Zinner: In Situ Observations of Energetic Heavy Ions.
F. M. IPAVICH, A. B. GALVIN, G. GLOECKLER, D. HOVESTADT, B. KLECKER, and M. SCHOLER (1986)
Science 232, 366-369
   Abstract »    PDF »
Ion Composition Results During the International Cometary Explorer Encounter with Giacobini-Zinner.
K. W. OGILVIE, M. A. COPLAN, P. BOCHSLER, and J. GEISS (1986)
Science 232, 374-377
   Abstract »    PDF »
Plasma Wave Observations at Comet Giacobini-Zinner.
F. L. SCARF, F. V. CORONITI, C. F. KENNEL, D. A. GURNETT, W.-H. IP, and E. J. SMITH (1986)
Science 232, 377-381
   Abstract »    PDF »
International Cometary Explorer Encounter with Giacobini-Zinner: Magnetic Field Observations.
E. J. SMITH, B. T. TSURUTANI, J. A. SLVAIN, D. E. JONES, G. L. SISCOE, and D. A. MENDIS (1986)
Science 232, 382-385
   Abstract »    PDF »


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