STRUCTURES IN THE PROTOPLANETARY DISK OF HD142527 SEEN IN POLARIZED SCATTERED LIGHT

We present H-and K-s-band polarized differential images of the Herbig Ae/ Be star HD142527, revealing its optically thick outer disk and the nearly empty gap. The very small inner working angle (similar to 0 ''.1) and high-resolution achievable with an 8 m class telescope, together with a careful polarimetric calibration strategy, allow us to achieve images that surpass the quality of previous scattered-light images. Previously known substructures are resolved more clearly and new structures are seen. Specifically, we are able to resolve (1) half a dozen spiral structures in the disk, including previously known outer-disk spirals as well as new spiral arms and arcs close to the inner rim of the disk, (2) peculiar holes in the polarized surface brightness at position angles (P. A.'s) of similar to 0 degrees and similar to 160 degrees, (3) the inner rim on the eastern side of the disk, and (4) the gap between the outer and inner disk, ranging from the inner working angle of 0 ''.1 out to between 0 ''.7 and 1 ''.0, which is nearly devoid of dust. We then use a Markov Chain Monte Carlo algorithm to determine several structural parameters of the disk, using very simple assumptions, including its inclination, eccentricity, and the scale height of the inner rim. We compare our results with previous work on this object and try to produce a consistent picture of the system and its transition disk.