Radial decoupling of small and large dust grains in the transitional disk RX J1615.3-3255

TL;DR

This study uses polarized light imaging to analyze the structure and dust grain distribution in the transitional disk RX J1615.3-3255, revealing insights into dust processing and disk morphology.

Contribution

It provides the first H-band polarized light observations of RX J1615.3-3255 and compares different dust models to interpret the disk's structure and dust grain distribution.

Findings

Disk extends to 68 AU in scattered light.

Small dust grains likely extend into the cavity, indicating dust processing.

Models with smoothly distributed small grains fit observations better.

Abstract

We present H-band (1.6 {\mu}m) scattered light observations of the transitional disk RX J1615.3-3255, located in the ~1 Myr old Lupus association. From a polarized intensity image, taken with the HiCIAO instrument of the Subaru Telescope, we deduce the position angle and the inclination angle of the disk. The disk is found to extend out to 68 $\pm$ 12 AU in scattered light and no clear structure is observed. Our inner working angle of 24 AU does not allow us to detect a central decrease in intensity similar to that seen at 30 AU in the 880 {\mu}m continuum observations. We compare the observations with multiple disk models based on the Spectral Energy Distribution (SED) and submm interferometry and find that an inner rim of the outer disk at 30 AU containing small silicate grains produces a polarized intensity signal which is an order of magnitude larger than observed. We show that a model in which the small dust grains extend smoothly into the cavity found for large grains is closer to the actual H-band observations. A comparison of models with different dust size distributions suggests that the dust in the disk might have undergone significant processing compared to the interstellar medium.