Thursday, June 7, 2012

1206.1273 (P. C. Frisch et al.)

The Interstellar Magnetic Field Close to the Sun II    [PDF]

P. C. Frisch, B-G Andersson, A. Berdyugin, V. Piirola, R. DeMajistre, H. O. Funsten, A. M. Magalhaes, D. B. Seriacopi, D. J. McComas, N. A. Schwadron, J. D. Slavin, S. J. Wiktorowicz
The magnetic field in the local interstellar medium (ISM) provides a key indicator of the galactic environment of the Sun and influences the shape of the heliosphere. The direction of the interstellar magnetic field (ISMF) near the Sun is studied using polarized starlight. The local ISMF direction is found from matching the polarization position angles for interstellar data towards nearby stars using weighted fits. New polarization observations are presented and used in the analysis. The local field is close to the ISMF direction found from the center of the Ribbon of energetic neutral atoms discovered by the Interstellar Boundary Explorer mission. Both the magnetic field and kinematics of the local ISM are consistent with a scenario where the local ISM is a fragment of the Loop I superbubble. An ordered component of the local ISMF is found in a region where PlanetPol data show that polarization increases with distance. It extends to within 8 parsecs of the Sun and implies a weak curvature in the nearby ISMF. Variations from the ordered component indicate turbulence of +/-23 deg. The ISMF is relatively uniform over spatial scales of 8-200 parsecs and is more similar to interarm magnetic fields. The ISMF direction is also consistent with spatial asymmetries in GeV-TeV galactic cosmic rays. The peculiar geometry between the CMB dipole moment, the heliosphere nose, and local ISMF is supported. Radiative torques are not likely to play a role in grain alignment for these polarizations.
View original: http://arxiv.org/abs/1206.1273

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