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We investigate the dust and gas distribution in the disk around HD 142527based on ALMA observations of dust continuum, 13CO(3-2), and C18O(3-2)emission. The disk shows strong azimuthal asymmetry in the dust continuumemission, while gas emission is more symmetric. In this paper, we investigatehow gas and dust are distributed in the dust-bright northern part of the diskand in the dust-faint southern part. We construct two axisymmetric disk models.One reproduces the radial profiles of the continuum and the velocity moments 0and 1 of CO lines in the north and the other reproduces those in the south. Wehave found that the dust is concentrated in a narrow ring having ~50AU width(in FWHM; w_d=30AU in our parameter definition) located at ~170-200AU from thecentral star. The dust particles are strongly concentrated in the north. Wehave found that the dust surface density contrast between the north and southamounts to ~70. Compared to the dust, the gas distribution is more extended inthe radial direction. We find that the gas component extends at least from~100AU to ~250AU from the central star, and there should also be tenuous gasremaining inside and outside of these radii. The azimuthal asymmetry of gasdistribution is much smaller than dust. The gas surface density differs only bya factor of ~3-10 between the north and south. Hence, gas-to-dust ratiostrongly depends on the location of the disk: ~30 at the location of the peakof dust distribution in the south and ~3 at the location of the peak of dustdistribution in the north. Despite large uncertainties, the overall gas-to-dustratio is inferred to be ~10-30, indicating that the gas depletion may havealready been under way.

Significant Gas-to-Dust Ratio Asymmetry and Variation in the Disk of HD 142527 and the Indication of Gas Depletion