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تسجيل مستخدم جديدConnecting the interstellar magnetic field at the heliosphere to the Loop I superbubble
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The local interstellar magnetic field affects both the heliosphere and the surrounding cluster of interstellar clouds (CLIC). Measurements of linearly polarized starlight provide the only test of the magnetic field threading the CLIC. Polarization measurements of the CLIC magnetic field show multiple local magnetic structures, one of which is aligned with the magnetic field traced by the center of the ribbon of energetic neutral atoms discovered by the Interstellar Boundary Explorer (IBEX). Comparisons between the bulk motion of the CLIC through the local standard of rest, the magnetic field direction, the geometric center of Loop I, and the polarized dust bridge extending from the heliosphere toward the North Polar Spur direction all suggest that the CLIC is part of the rim region of the Loop I superbubble.
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Starlight that becomes linearly polarized by magnetically aligned dust grains provides a viable diagnostic of the interstellar magnetic field (ISMF). A survey is underway to map the local ISMF using data collected at eight observatories in both hemis
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A key indicator of the galactic environment of the Sun is provided by the magnetic field in the interstellar medium (ISM), which influences the shape of the heliosphere. The direction of the nearby interstellar magnetic field (ISMF) is determined fro
m starlight polarized in the ISM. The local ISMF direction is found from the ISMF direction that provides the best fit to the polarization position angles of nearby stars, using weighted fits to the data. New polarization observations are included in the analysis. The best-fitting ISMF is close to the magnetic field direction traced by the center of the Ribbon of energetic neutral atoms, discovered by the Interstellar Boundary Explorer spacecraft. 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 local ISMF is generally uniform in direction over spatial scales of 8-200 parsecs so that it appears similar to interarm magnetic fields. The best-fitting ISMF direction also agrees with the position of tail-in spatial asymmetries in GeV-TeV galactic cosmic rays. The peculiar geometrical relation between the CMB dipole moment, the heliosphere nose, and local ISMF is supported by these new results. Radiative torques are not likely to play a role in grain alignment for these polarizations.
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