  We present ALMA observations of the 0.88 millimeter dust continuum, 13CO, and
C18O J=3-2 line emission of the circumbinary disk HD142527 at a spatial
resolution of about 0.25". This system is characterized by a large central
cavity of roughly 120 AU in radius, and asymmetric dust and gas emission. By
comparing the observations with theoretical models, we find that the azimuthal
variations in gas and dust density reach a contrast of 54 for dust grains and
3.75 for CO molecules, with an extreme gas-to-dust ratio of 1.7 on the dust
crescent. We point out that caution is required in interpreting continuum
subtracted maps of the line emission as this process might result in removing a
large fraction of the line emission. Radially, we find that both the gas and
dust surface densities can be described by Gaussians, centered at the same disk
radius, and with gas profiles wider than for the dust. These results strongly
support a scenario in which millimeter dust grains are radially and azimuthally
trapped toward the center of a gas pressure bump. Finally, our observations
reveal a compact source of continuum and CO emission inside the dust depleted
cavity at about 50 AU from the primary star. The kinematics of the CO emission
from this region is different from that expected from material in Keplerian
rotation around the binary system, and might instead trace a compact disk
around a third companion. Higher angular resolution observations are required
to investigate the nature of this source.
