Dual-band, Multi-aperture Polarization Measurements of β Pictoris

We present high precision, dual-band aperture polarimetry of the β Pictoris debris disk. The polarization is aperture dependent, increasing from 5″ to 19″ and peaking, after interstellar subtraction at around 230–240 ppm in both g ′ and r ′ bands; the polarization vector is oriented perpendicular to the disk major-axis. By simple calculations, lower limits are placed on the polarization of scattered light interior to 200 au. The observations and calculations are consistent with prior spatially resolved polarimetric measurements of the disk that probe greater angular separations, and models for the interior developed from them.