Continuum image at 330 GHz. The beam size of 0.19″ × 0.14″, PA = 190° is indicated in the lower left corner. The contour levels are 0.5, 1, 2, 4, 8 and 16 mJy beam⁻¹. The noise level is 0.06 mJy beam⁻¹. The red ellipses indicate the inner and outer edges of the dense dust ring at 180 au and 260 au, respectively (e.g., Guilloteau et al. 1999). The positions of the Aa star and Ab close binary are indicate by the crosses. The inset shows an enlarged view of the Aa and Ab surroundings.