Disconnection Events of Comet Halley 1985-1986 and Global Magnetohydrodynamic Simulations.

Details Disconnection Events of Comet Halley 1985-1986 and Global Magnetohydrodynamic Simulations. Disconnection Events of Comet Halley 1985-1986 and Global Magnetohydrodynamic Simulations.

Jan 1994

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994phdt........13y&link_type=abstract

Thesis (PH.D.)--UNIVERSITY OF COLORADO AT BOULDER, 1994.Source: Dissertation Abstracts International, Volume: 56-03, Section: B,

Astronomy and Astrophysics

Astronomy

2

Scientific paper

A disconnection event (DE) of the cometary plasma tail is one of the most spectacular phenomena observed in comets. Yet, for years it has remained one of the great unsolved problems in astronomy and space physics. The goal of this thesis is to present a mechanism that explains the disconnection event in terms of the local conditions at the comet. The solar wind is thought to play a major role in the creation of comet plasma tail (type I) disconnection events. In order to study the physics of a DE, one must determine the kinematics and solar wind conditions experienced by the comet at the time of the DE--including the interplanetary magnetic field (IMF) and the solar wind's velocity, density, and temperature. To illustrate such conditions, cometary and solar wind data associated with plasma tail disconnection events during Comet Halley's most recent apparition are presented. The cometary data for the period beginning December 1985 and ending April 1986 are from The International Halley Watch Atlas of Large-Scale Phenomena (Brandt, Niedner and Rahe 1992). In situ wind measurements from IMP-8, ICE, and PVO were used to construct the variation of solar wind speed, density, and dynamic pressure during this time. Data from these same spacecraft plus Vega-1 were used to determine the time of 48 current sheet crossings. These data were fitted to heliospheric current sheet (HCS) curves (Hoeksema 1989) extrapolated from the corona into the heliosphere in order to determine the best-fit source surface radius for each Carrington rotation. Comparison of the solar wind conditions and 16 DEs in Halley's comet shows that DEs are associated primarily with crossings of the HCS and apparently not with any other properties of the solar wind, such as a high speed stream. A 3-dimensional resistive magnetohydrodynamic simulation supports this association by showing that only front-side magnetic reconnection between the reversed interplanetary magnetic fields that exist when a comet crosses the HCS (Niedner and Brandt 1978) could reproduce the morphology of a DE, including ray formation (Brandt 1982). This link between comets and the solar wind can be explored wherever a comet may appear--even to high solar latitudes. Exploration of solar wind properties and their effect on comets is one goal of the ongoing Ulysses Comet Watch project.

Affiliated with

Also associated with

No associations

Rating

Disconnection Events of Comet Halley 1985-1986 and Global Magnetohydrodynamic Simulations. 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 Disconnection Events of Comet Halley 1985-1986 and Global Magnetohydrodynamic Simulations., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Disconnection Events of Comet Halley 1985-1986 and Global Magnetohydrodynamic Simulations. will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1684982