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Termination Shock Asymmetries as Seen by the Voyager Spacecraft: The Role of the Interstellar Magnetic Field and Neutral Hydrogen

Pogorelov, Nikolai V. and Stone, Edward C. and Florinski, Vladimir and Zank, Gary P. (2007) Termination Shock Asymmetries as Seen by the Voyager Spacecraft: The Role of the Interstellar Magnetic Field and Neutral Hydrogen. Astrophysical Journal, 668 (1). pp. 611-624. ISSN 0004-637X.

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We show that asymmetries of the termination shock due to the influence of the interstellar magnetic field (ISMF) are considerably smaller in the presence of neutral hydrogen atoms, which tend to symmetrize the heliopause, the termination shock, and the bow shock due to charge exchange with charged particles. This leads to a much stronger restriction on the ISMF direction and its strength. We demonstrate that in the presence of the interplanetary magnetic field the plane defined by the local interstellar medium (LISM) velocity and magnetic field vectors does not exactly coincide with the plane defined by the interstellar neutral helium and hydrogen velocity vectors in the supersonic solar wind region, which limits the accuracy of the inferred direction of the ISMF. We take into account the tilt of the LISM velocity vector with respect to the ecliptic plane and show that magnetic fields as strong as 3 μG or greater may be necessary to account for the observed asymmetry. Estimates are made of the longitudinal streaming anisotropy of energetic charged particles at the termination shock caused by the nonalignment of the interplanetary magnetic field with its surface. By investigating the behavior of interplanetary magnetic field lines that cross the Voyager 1 trajectory in the inner heliosheath, we estimate the length of the trajectory segment that is directly connected by these lines to the termination shock. A possible effect of the ISMF draping over the heliopause is discussed in connection with radio emission generated in the outer heliosheath.

Item Type:Article
Related URLs:
URLURL TypeDescription
Stone, Edward C.0000-0002-2010-5462
Florinski, Vladimir0000-0001-5485-2872
Zank, Gary P.0000-0002-4642-6192
Additional Information:© 2007. The American Astronomical Society. Received 2007 April 12; accepted 2007 June 6. This work was supported by NASA grants NNG05GD45G, NNG06GD48G, and NNG06GD43G and NSF award ATM-0296114. Calculations were performed on the supercomputers Fujitsu Primepower HPC2500, in the framework of the collaborative agreement with the Solar-Terrestrial Environment Laboratory of Nagoya University, Columbia at NASA Ames Research Center (award SMD-06-0167), and IBM DataStar, on the basis of the Academic Associates Program and award ATM-070011, at the San Diego Supercomputer Center.
Group:Space Radiation Laboratory
Subject Keywords:ISM: kinematics and dynamics—magnetic fields—MHD—shock waves—solar wind
Issue or Number:1
Record Number:CaltechAUTHORS:POGapj07
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9151
Deposited By: Archive Administrator
Deposited On:04 Nov 2007
Last Modified:09 Mar 2020 13:19

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