# Detailed modeling of dust distribution in the disk of HD 142527

## TL;DR

This study models the dust distribution in the HD 142527 disk using ALMA data, revealing that reduced scattering opacity better explains the observed intensity, especially in the northwestern region, indicating lower albedo than previously assumed.

## Contribution

It introduces a detailed azimuthal sector-based modeling approach that accounts for scattering and inclination, improving understanding of dust properties in protoplanetary disks.

## Key findings

- Reducing scattering opacity by a factor of 10 reproduces observed intensity.
- Dust surface density contrast along PA is about 40.
- Lower albedo is suggested in the northwestern region.

## Abstract

We investigate the dust distribution in the crescent disk around HD 142527 based on the continuum emission at $890 \mathrm{\ \mu m}$ obtained by ALMA Cycle 0. The map is divided into $18$ azimuthal sectors, and the radial intensity profile in each sector is reproduced with a 2D disk model. Our model takes account of scattering and inclination of the disk as well as the azimuthal dependence in intensity. When the dust is assumed to have the conventional composition and maximum size of $1\ \mathrm{mm}$, the northwestern region ($PA=329^{\circ}-29^{\circ}$) cannot be reproduced. This is because the model intensity gets insensitive to the increase in surface density due to heavy self-scattering, reaching its ceiling much lower than the observed intensity. The ceiling depends on the position angle. When the scattering opacity is reduced by a factor of $10$, the intensity distribution is reproduced successfully in all the sectors including those in the northwestern region. The best fit model parameters depend little on the scattering opacity in the southern region where the disk is optically thin. The contrast of dust surface density along $PA$ is derived to be about $40$, much smaller than the value for the cases of conventional opacities ($70-130$). These results strongly suggest that the albedo is lower than considered by some reasons at least in the northwestern region.