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A disturbance of the ion tail of comet Halley and the heliospheric structure as observed by Sakigake
Author(s) -
Saito Takao,
Yumoto Kiyohumi,
Hirao Kunio,
Saito Keiji,
Nakagawa Tomoko,
Smith Edward J.
Publication year - 1986
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl013i008p00821
Subject(s) - comet , solar wind , physics , plasmoid , heliosphere , comet tail , astronomy , halley's comet , plasma , magnetic reconnection , quantum mechanics
In order to study the interaction between the solar wind measured by Sakigake and ion tail disturbances of comet Halley, more than 500 photographs of the comet taken on the ground during this apparition are surveyed. The focus of the present study is the December 31, 1985, event, when various types of disturbances occurred, including an outstanding disconnection event (DE)‐ like knot. Analysis of the Sakigake/IMF data reveals that comet Halley did not encounter the heliospheric neutral sheet on that day, demanding a new explanation for the DE‐like event, different from the Niedner‐Brandt model. During this event the comet encountered a high‐speed solar wind stream from a coronal hole tongue of the sun. The event can be explained by a dynamic pressure model, according to which the DE‐like plasmoid was caused by a sudden increase in the dynamic pressure of the solar wind. A result of the simulation work by Ogino is found to support this interpretation.