High-Contrast NIR Polarization Imaging of MWC480

– 3 –ABSTRACTOne of the key predictions of modeling from the IR excess of Herbig Aestars is that for protoplanetary disks, where significant grain growth and settlinghas occurred, the dust disk has flattened to the point that it can be partiallyor largely shadowed by the innermost material at or near the dust sublimationradius. When the self-shadowing has already started, the outer disk is expectedto be detected in scattered light only in the exceptional cases that the scale heightof the dust disk at the sublimation radius is smaller than usual. High-contrastimaging combined with the IR spectral energy distribution allow us to measurethe degree of flattening of the disk, as well as to determine the properties of theouter disk. We present polarimetric differential imaging in H band obtained withSubaru/HiCIAO of one such system, MWC 480. The HiCIAO data were obtainedat a historic minimum of the NIR excess. The disk is detected in scattered lightfrom 0.′′2-1.′′0 (27.4-137AU). Together with the marginal detection of the disk from1998 February 24 by HST/NICMOS, our data constrain the opening half anglefor the disk to lie between 1.3≤θ ≤2.2