Interstellar Dust and Magnetic Field at the Heliosphere

The very weak polarization of light from nearby stars reaches a maximum near the ecliptic plane in a position offset by λ ∼ 35 from the heliosphere nose direction. The position angle for the polarization in this ecliptic-plane peak is the same for near and distant stars, to within uncertainties, indicating the interstellar magnetic field direction is relatively constant over several hundred parsecs in this region. This region is near the center of a magnetic bubble that has recently been identified by Wolleben. The magnetic field directions defined by the polarizations of nearby and distant stars in the direction of this polarization maximum, and also by the observed offset between interstellar He and H flowing into the heliosphere, converge to a local magnetic field direction that is inclined by ∼ 55 with respect to the galactic plane, or ∼ 65 with respect to the ecliptic plane. Surprisingly, the geometry of the cosmic microwave background (CMB) dipole moment shows a strong correlation with this heliosphere geometry. Several vectors associated with the CMB low-l multipole moments are located at the positions of heliosphere landmarks such as the 3 kHz emissions detected by the Voyager 1 and Voyager 2 satellites. Together these results suggest that an unrecognized heliospheric foreground is present in the measured CMB background. All data are consistent with the expansion of the S1 subshell of the Loop I magnetic bubble to the solar location. The magnetic field in this shell then determines the field direction at the Sun, helps shape the heliosphere, and generates an additional unrecognized CMB foreground. Subject headings: ISM: magnetic fields, dust, heliosphere— cosmology: miscellaneous— solar system: general February 1, 2008. “Dust and Heliosphere” 2