title: Anomalous flow deflection at earth's low-Alfvén-Mach-Number bow shock.
abstract: Earth's magnetosphere is an obstacle to the supersonic solar wind and the bow shock is formed in the front side of it. In ordinary hydrodynamics, the flow decelerated at the shock is diverted around the obstacle symmetrically about the Earth-Sun line, which is indeed observed in the magnetosheath most of the time. Here we show a case under a very low-density solar wind in which duskward flow was observed in the dawnside magnetosheath. A Rankine-Hugoniot test shows that the magnetic effect is crucial for this "wrong flow" to appear. A full three-dimensional magnetohydrodynamics (MHD) simulation of the situation confirming this interpretation and earlier simulations is also performed. It is illustrated that in addition to the "wrong flow" feature, various peculiar characteristics appear in the global picture of the MHD flow interaction with the obstacle.
authors.affiliation: Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510, Japan. nishino@stp.isas.jaxa.jp
authors.forename: Masaki N
authors.initials: MN
authors.lastname: Nishino
authors.forename: Masaki
authors.initials: M
authors.lastname: Fujimoto
authors.forename: Tai-Duc
authors.initials: TD
authors.lastname: Phan
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Mukai
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Saito
authors.forename: Masha M
authors.initials: MM
authors.lastname: Kuznetsova
authors.forename: Lutz
authors.initials: L
authors.lastname: Rastätter