Near-infrared imaging polarimetry of HD142527

Abstract

Context. HD142527 is a pre-transition disk with strong evidence for ongoing planet formation. Recent observations show a disrupted disk with spiral arms, a dust-depleted inner cavity and the possible presence of gas streams driving gas from the outer disk toward the central star. Aims. We aim to derive the morphology of the disk and the distribution and properties of the dust at its surface. Methods. We have obtained polarized di erential images of HD142527 at H and Ks bands with NaCo at the VLT. Combining these images with classical PSF-subtraction, we are able to derive the polarization degree of this disk. Results. At H band the polarization degree of the disk varies between 10% and 25%. This result cannot be reproduced by dust distributions containing highly porous material. The polarization is better matched by distributions of compact particles, with maximum sizes at least up to a few microns, in agreement with previous observations. We also observe two regions of low emission (nulls) in total and in polarized intensity. In particular, one of these nulls is at roughly the same position as the maximum of the horse-shoe shape observed in submillimeter continuum emission ALMA band-7 (345 GHz) observations. We discuss the possible link between these two features.