Kinematical Signs of Dust Trapping and Feedback in a Local Pressure Bump in the Protoplanetary Disk around HD 142527 Revealed with ALMA

Abstract

We analyzed the archival data of the continuum emission at six wavelengths from 3 to 0.4 mm and 13 CO and C 18 O (1–0, 2–1, and 3–2) lines in the protoplanetary disk around HD 142527 obtained with the Atacama Large Millimeter/submillimeter Array. We performed fitting to the spectral energy distributions obtained at the six wavelengths with the graybody slab models to estimate the distributions of the dust surface density and spectral index of dust absorption coefficient β . We also estimated the distribution of the gas column density by fitting the C 18 O spectra and measured the disk rotation by fitting the Keplerian disk models to the C 18 O data. We found super- and sub-Keplerian rotation inside and outside the dust ring in the northwest in the HD 142527 disk, suggestive of the presence of a local pressure bump. In comparison with our estimated dust and gas distributions, the location of the pressure bump is coincident with the region showing a three times higher dust density and a three times lower gas-to-dust mass ratio than the mean values in the disk, suggesting dust trapping in the pressure bump. Nevertheless, there is no correlation between our derived β distribution and the location of the pressure bump. In addition, we found that the width of the dust ring is comparable to or larger than the width of the pressure bump, which could suggest that dust feedback is significant in the pressure bump.