title: New SMA and PdBI observations of the protoplanetary disk around AB Aurigae

authors: Nagayoshi Ohashi, Ya-Wen Tang, Stephane Guilloteau, Vincent Pietu, Anne Dutrey, and Paul Ho

abstract: The protoplanetary disk of AB Aurigae has garnered great attentions due to
the apparent existence of spirals at a relatively young stage and also the
asymmetric disc traced in thermal dust emission. However, the physical
conditions of the spirals are still not well understood, and the origin of
the asymmetric thermal emission is also unclear. In order for us to have
better understanding of these features, we observe the disc at 230 GHz (1.3
mm) in both continuum and the spectral line 12CO J=2-1 with IRAM 30 m, the
Plateau de Bure Interferometer and the Submillimeter Array to sample all
spatial scales from 0.37" to about 50". The protoplanetary disk is resolved
into inner and outer disc (dust ring) at 1.3 mm continuum. Associated with
the inner disc, molecular gas at high velocities traced by the CO line is
detected aside the stellar location. The emission from the dust ring is
highly asymmetric in azimuth, where intensity contrast in the dust ring is
3. The width of the gap between these two discs is ~45 AU. Based on the
intensity weighted dispersion and the integrated intensity map of 12CO
J=2-1, four spirals are identified, where two of them are also detected in
the near-infrared. The inclination angle of the disc is found to decrease
toward the center. The total gas mass of the 4 spirals (Mspiral) is 10^-7 <
Mspiral < 10^-5 Mo, which is 3 orders of magnitude smaller than the mass of
the disc. Detailed analysis of the spirals kinematics suggested that it can
be explained as either a counter-clockwise rotation with an inward motion
or a counter-clockwise Keplerian rotation with spirals produced via density
wave. The spiral might counter-rotates compared to the disk.