HR: 1340h
AN: SH43A-1100    [Abstracts]
TI: V-Shaped Heliosphere and Dependence of Solar-Cycle-Variations on Trajectories of Galactic Cosmic Rays
AU: * Washimi, H
EM: washimi@info.shonan-it.ac.jp
AF: Institute of Geophysics and Planetary Physics, UCR, Riverside, Riverside, CA 92521 United States
AU: Tanaka, T
EM: tatanaka@geo.kyushu-u.ac.jp
AF: Faculty of Science, Kyushu University, Hakozaki, Fukuoka, 812-8581 Japan
AU: Ono, M
EM: mr.mac@e-ml.jp
AF: Fujisoft ABC Inc., Sakuragityou 1-1, Naka-ku, Yokohama, 231-8795 Japan
AU: Munakata, K
EM: kmuna00@gipac.shinshu-u.ac.jp
AF: Faculty of Science, Shinshu University, Asahi 3-1-1, Matsumoto, 390-8621 Japan
AU: Shimazu, H
EM: shimazu@crl.go.jp
AF: National Institute of Information and Communications Technology, NUkui-Kitamachi, Koganei, Tokyo, 184-8795 Japan
AB: It has long been believed that the global structure of the heliopause under the interaction of the solar wind and the LISM is a simple nose-cone type. However, once the equatorial magnetic neutral sheet of the solar wind along the equatorial plane is taken into account, the situation changes drastically. The ram-pressure of the solar wind is no longer isotropic in the interplanetary space in this case. As a result, it is not easy to find a new stationary state because MHD simulation analyses tend to face non-stationary states of the heliopause, where the solar wind plasma coming from the inner side region extends from the nose cone surface by forming long-lived vortices. By using our MHD simulation, we found that a 3D stationary heliopause in this case is a V-shaped gutter on the nose-cone surface along the equatorial plane, and that the high ram-pressure equatorial sheet plasma is vented to a high-latitudinal region along the termination shock surface in the outer heliosphere. The self-consistency of this new structure will be discussed. Trajectories of cosmic-rays in the global 3-D magnetic heliosphere, which includes the effect of the solar-cycle-variations in the above MHD simulation model, are traced numerically. To simulate the propagation of high-energy galactic cosmic-ray protons to the earth, we eject anti-protons from the earth in various directions and trace their orbits back to the interstellar space by using the fourth order Runge-Kutta method. We make calculations mainly for 500 GeV cosmic ray protons, and find in our analyses that there are two major groups of particles. One group of particles is arriving at the earth from a wide range of the heliotail with their orbits significantly deflected at the magnetic wall formed in the upstream side of the heliosheath. The other group of particles also comes from the heliotail, meandering along the neutral surface of the heliopause sandwiched between the heliosheath magnetic field and the LISM field, which are opposite to each other in direction. We also find that cosmic rays in the inner heliosphere are arriving from the polar region or along the equatorial sheet due to the gradient and curvature drift, which is strongly dependent upon the solar-cycle-variations of the magnetic field. Preliminary results of a particle simulation for the study of how the galactic cosmic rays come across the heliopause surface will be also discussed.
DE: 2104 Cosmic rays
DE: 2124 Heliopause and solar wind termination
DE: 2134 Interplanetary magnetic fields
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting