Optical polarization in the disc around β Pictoris

Abstract

Imaging polarimetry of the β Pic disc shows that it is reflection nebulosity solely illuminated by the central star. The level of polarization in both segments of the disc is 17 ± 3 per cent (R waveband) and is relatively constant in the distance range 15-30 arcsec from the star. We find that the β Pic disc shows up in polarized light when we treat the light surrounding the bright star as simple reflection nebulosity. This procedure does not require complicated background subtractions from reference stars and should provide a simple and fast method of locating planetary and protoplanetary discs surrounding other stars.