2011AJ....142..151L

We present ∼1'' resolution 1.3 mm dust continuum and spectral line (¹²CO and ¹³CO J = 2-1) observations of the transitional disk system HD 135344B obtained with the Submillimeter Array. The disk shows a Keplerian rotation pattern with an inclination of ∼11°, based on the spatially and spectrally resolved ¹²CO and ¹³CO emission. The data show clear evidence for both dust and gas surface density reductions in the inner region of the disk (radius ≲ 50 AU) from the continuum and ¹³CO J = 2-1 data, respectively. The presence of this inner cavity in both the dust and gas is more consistent with clearing by giant planet formation than by photoevaporation or by grain growth. There is also an indication of global CO gas depletion in the disk, as the mass estimated from ¹³CO emission (∼3.8x10^–4 M_☉) is about two orders of magnitude lower than that derived from the 1.3 mm continuum (∼2.8x10^–2 M_☉).