IMAGING POLARIMETRY OF HL-TAURI AND GG-TAURI - A GEOMETRICALLY THIN DISK AROUND GG-TAURI

Polarimetric imaging observations in the K' band toward HL Tau and GG Tau were made using the University of Hawaii 2.2 m telescope. While both T Tauri stars are associated with gaseous circumstellar material extended more than 500 AU in radius, a reflection nebula was found only around HL Tau. We suggest that the HL Tau nebula is most likely light scattered by the dust grains at a high latitude above the disk plane. The absence of a reflection nebula around GG Tau can be explained if the dust grains are confined close to the disk plane. The thin GG Tau disk could be a protosolar nebula or a site of ongoing solar system formation.