HR: 09:05h
AN: SH31B-01 INVITED     [Abstracts]
TI: The Global Structure of the Heliosphere: an Assessment After the First Termination-Shock Crossing
AU: * Jokipii, J R
EM: jokipii@lpl.arizona.edu
AF: University of Arizona, Department of Planetary Sciences, Tucson, AZ 85721 United States
AB: The existence of the heliosphere was not known prior to the middle of the 20th century. Since then, a combination of theory and both remote and in situ observations established the heliosphere and gradually revealed much of its structure and dynamics. This past December, an important milestone was passed, as Voyager 1 crossed the termination shock marking the end of the supersonic solar wind, at 94 AU. The various observations will be discussed in this talk and used to provide a current, but still evolving, picture of global heliospheric structure and its interaction with the local interstellar medium (LISM). Because the wind is highly supersonic and very nearly radial, from very near the Sun out to the termination shock, the large-scale structure of the plasma and magnetic field inside of the shock are mainly determined by the initial and boundary conditions near the Sun. They depend much less on the conditions in the LISM. Observations from Ulysses, which traversed essentially all heliographic latitudes, together with in situ observations from other spacecraft, remote observations and theory, have permitted a reasonably accurate picture of global heliospheric structure inside of the termination shock to be assembled. However, this supersonic nature of the solar wind also has made it difficult to obtain an accurate picture of the region of interaction of the heliosphere with the LISM, at and beyond the termination shock. Cosmic rays and other energetic charged particles, which are very mobile have served as invaluable probes of these outer regions. But in situ observations by Voyager 1 finally established the scale, and illuminated the physics, by recently observing near-shock upstream phenomena and then crossing the termination shock for the first time in December, 2004. The emerging picture suggests a very dynamic termination shock and inner heliosheath. Continuing observations by Voyager 1, as it moves into the heliosheath, and from Voyager 2, still in the supersonic solar wind, will further clarify our understanding of this important region of space.
DE: 2124 Heliopause and solar wind termination
DE: 2126 Heliosphere/interstellar medium interactions
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005