HR: 11:29h
AN: SH52A-04    [Abstracts]
TI: Are high-latitude forward-reverse shock pairs driven by over-expansion?
AU: * Manchester, W B
EM: chipm@umich.edu
AF: Dept. Atmospheric Oceanic and Space Science/University of Michigan, 2455 Hayward Street, Ann Arbor, MI 49109 United States
AU: Zurbuchen, T H
EM: thomasz@umich.edu
AF: Dept. Atmospheric Oceanic and Space Science/University of Michigan, 2455 Hayward Street, Ann Arbor, MI 49109 United States
AU: Gombosi, T I
EM: tamas@umich.edu
AF: Dept. Atmospheric Oceanic and Space Science/University of Michigan, 2455 Hayward Street, Ann Arbor, MI 49109 United States
AU: De Zeeuw, D L
EM: darrens@umich.edu
AF: Dept. Atmospheric Oceanic and Space Science/University of Michigan, 2455 Hayward Street, Ann Arbor, MI 49109 United States
AU: Sokolov, I V
EM: igorsok@umich.edu
AF: Dept. Atmospheric Oceanic and Space Science/University of Michigan, 2455 Hayward Street, Ann Arbor, MI 49109 United States
AU: Toth, G
EM: gtoth@grid.engin.umich.edu
AF: Dept. Atmospheric Oceanic and Space Science/University of Michigan, 2455 Hayward Street, Ann Arbor, MI 49109 United States
AB: During its passage through the high-latitude heliosphere, Ulysses observed Interplanetary CMEs (ICMEs) bounded by shocks. These forward-reverse shock pairs have only been observed at high latitude in the fast solar. It has been suggested (e.g. Gosling et al. 1995) that these shock pairs are the result of the expansion of the coronal mass ejection in the ambient solar wind, so called "over-expansion". Here we demonstrate and alternative explanation for forward-reverse shock pairs by means of a three-dimensional (3-D) numerical ideal magnetohydrodynamics (MHD) model of a CME interacting with the solar wind. Our global steady-state coronal model possesses fast and slow speed solar wind at high and low latitude respectively reminiscent of near solar minimum conditions. Within this model system, a CME erupts from the coronal streamer belt with an initial speed in excess of 1000 km/s which naturally drives a forward shock. When the CME is greater than 40 Rs from the Sun, we find that a reverse shock forms poleward of the CME as a result of the interaction of the CME with the bimodal solar wind. In front of the CME, the slow wind is deflected to higher latitude while behind the CME, fast wind is deflected to low latitude. The deflected streams collide to form a reverse shock. The shock pair formed in this way naturally forms at high latitude in the fast wind stream. We will discuss these model results in the context of in situ solar wind data and make testable predictions based on this model.
DE: 6944 Nonlinear phenomena
DE: 7513 Coronal mass ejections
DE: 7524 Magnetic fields
DE: 7531 Prominence eruptions
DE: 7851 Shock waves
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2005 Joint Assembly