ALMA Observations of a Gapped Protoplanetary Disk
We present the results of ALMA Cycle 0 observations of dust continuum at 340 GHz, 13CO(3-2) and C18O(3-2) line emission toward a gapped protoplanetary disk around a Herbig Fe star, HD 142527. In the continuum with the angular resolution of about 60 AU (0.4 arcsec), the outer disk was readily resolved, showing a horseshoe shaped distribution associated with the strong azimuthal asymmetry with the contrast of about 30 between the northern peak and the southwestern minimum. The brightness temperature of the northern portion of the disk reaches to 24 K at maximum at 160 AU from the central star, which is exceptionally high compared to other disks. The surface density in this northern area was estimated using the temperature constraint obtained from the optically thick 13CO emission. Depending on the gas-to-dust mass ratio, self-gravity may cause disk fragmentation, or grain accumulation can lead to efficient growth of rocky objects.