Solving grain size inconsistency between ALMA polarization and VLA continuum in the Ophiuchus IRS 48 protoplanetary disk

Abstract

The protoplanetary disk around Ophiuchus IRS 48 shows an azimuthally asymmetric dust distribution in (sub-)millimeter observations, which is interpreted as a vortex, where millimeter/centimeter-sized particles are trapped at the location of the continuum peak. In this paper, we present 860 $\mu$m ALMA observations of polarized dust emission of this disk. The polarized emission was detected toward a part of the disk. The polarization vectors are parallel to the disk minor axis, and the polarization fraction was derived to be $1-2$\%. These characteristics are consistent with models of self-scattering of submillimeter-wave emission, which indicate a maximum grain size of $\sim 100$ $\mu$m. However, this is inconsistent with the previous interpretation of millimeter/centimeter dust particles being trapped by a vortex. To explain both, ALMA polarization and previous ALMA and VLA observations, we suggest that the thermal emission at 860 $\mu$m wavelength is optically thick (${\tau }_{\mathrm{abs}}\sim 7.3$) at the dust trap with the maximum observable grain size of $\sim 100$ $\mu$m rather than an optically thin case with $\sim$ cm dust grains. We note that we cannot rule out that larger dust grains are accumulated near the midplane if the 860 $\mu$m thermal emission is optically thick.

22 pages, 17 figures, accepted for publication in ApJ

References in corpus (22)

• Particle Stirring in Turbulent Gas Disks: Including Orbital Oscillations
• Gaps, Rings, and Non-Axisymmetric Structures in Protoplanetary Disks - From Simulations to ALMA Observations
• One Solution to the Mass Budget Problem for Planet Formation: Optically Thick Disks with Dust Scattering
• Lupus disks with faint CO isotopologues: low gas/dust or large carbon depletion?
• The Radial Distribution of Dust Particles in the HL Tau Disk from ALMA and VLA Observations
• Protoplanetary disk rings and gaps across ages and luminosities
• The evidence of radio polarization induced by the radiative grain alignment and self-scattering of dust grains in a protoplanetary disk
• The anomalously low (sub)millimeter spectral indices of some protoplanetary disks may be explained by dust self-scattering
• Dust Trapping by Vortices in Transitional Disks: Evidence for Non-ideal MHD Effects in Protoplanetary Disks
• Spatially Resolved Magnetic Field Structure in the Disk of a T Tauri Star
• ALMA Reveals Transition of Polarization Pattern with Wavelength in HL Tau's Disk
• Effects of dust feedback on vortices in protoplanetary disks
• Submillimeter polarization observation of the protoplanetary disk around HD 142527
• A cavity and further radial substructures in the disk around HD~97048
• Dust-trapping vortices and a potentially planet-triggered spiral wake in the pre-transitional disk of V1247 Orionis
• Spatial separation of small and large grains in the transitional disk around the young star IRS 48
• Nonsticky Ice at the Origin of the Uniformly Polarized Submillimeter Emission from the HL Tau Disk
• HD 169142 in the eyes of ZIMPOL/SPHERE
• Radial variations in grain sizes and dust scale heights in the protoplanetary disk around HD 163296 revealed by ALMA polarization observation
• Investigating dust trapping in transition disks with millimeter-wave polarization
• ALMA observations of Elias 2-24: a protoplanetary disk with multiple gaps in the Ophiuchus Molecular Cloud
• Dust concentration and emission in protoplanetary disks vortices

Cited by in corpus (8)

• A major asymmetric ice trap in a planet-forming disk: III. First detection of dimethyl ether
• The coexistence of the streaming instability and the vertical shear instability in protoplanetary disks: Planetesimal formation thresholds explored in two-dimensional global models
• How planets grow by pebble accretion IV: Envelope opacity trends from sedimenting dust and pebbles
• Eccentric Dust Ring in the IRS 48 Transition Disk
• A major asymmetric ice trap in a planet-forming disk IV. Nitric oxide gas and a lack of CN tracing sublimating ices and a C/O ratio $<1$
• Self-scattering on large, porous grains in protoplanetary disks with dust settling
• Polarization from Aligned Dust Grains in the $\beta$ Pic Debris Disk
• Sub-mm/mm optical properties of real protoplanetary matter derived from Rosetta/MIRO observations of comet 67P