An Observational Study for Grain Dynamics in the AS 209 Disk with Submillimeter Polarization

Abstract

We present 870 $\mu$m ALMA polarization observation toward the Class I\hspace{-.1em}I protoplanetary disk around AS 209, which has concentric, multiple gaps and rings. We successfully detect the polarized emission and find that the polarization orientations and fractions have distinct characteristics between the inner and outer regions. In the inner region, the polarization orientations are parallel to the minor axis of the disk, which is consistent with the self-scattering model. The mean polarization fraction in the region is $\sim$0.2\%, which is lower than the expected value when the grains have the maximum polarization efficiency, which corresponds to $\lambda$/2$\pi$ $\sim$ 140 $\mu$m in grain radius. In the outer region, we detect $\sim$1.0\% polarization and find that the polarization orientations are almost in the azimuthal directions. Moreover, the polarization orientations have systematic angular deviations from the azimuthal directions with $\Delta$$\theta$ $\sim$ 4\fdg5 $\pm$ 1\fdg6. The pattern is consistent with a model that radially drifting dust grains are aligned by the gas flow against the dust grains. We consider possible scenarios of the grain dynamics at the AS 209 ring which can reproduce the polarization pattern. However, the directions of the observed angular deviations are opposite to what is predicted under the fact that the disk rotates clockwise. This poses a question in our understandings of the alignment processes and/or grain dynamics in protoplanetary disks.

14 pages, 7 figures

References in corpus (25)

• Coagulation, fragmentation and radial motion of solid particles in protoplanetary disks
• Protoplanetary Disk Structures in Ophiuchus
• Ring shaped dust accumulation in transition disks
• Accretion in the Rho-Oph pre-main sequence stars
• A Millimeter Continuum Size-Luminosity Relationship for Protoplanetary Disks
• Mass Estimates of a Giant Planet in a Protoplanetary Disk from the Gap Structures
• Placing Confidence Limits on Polarization Measurements
• One Solution to the Mass Budget Problem for Planet Formation: Optically Thick Disks with Dust Scattering
• Multiple Disk Gaps and Rings Generated by a Single Super-Earth
• Dust retention in protoplanetary disks
• Global MHD simulations of stratified and turbulent protoplanetary discs. I. Model properties
• Survival of the mm-cm size grain population observed in protoplanetary disks
• The evidence of radio polarization induced by the radiative grain alignment and self-scattering of dust grains in a protoplanetary disk
• On the formation of multiple concentric rings and gaps in protoplanetary disks
• The anomalously low (sub)millimeter spectral indices of some protoplanetary disks may be explained by dust self-scattering
• Magnetic Flux Concentration and Zonal Flows in Magnetorotational Instability Turbulence
• 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
• Submillimeter polarization observation of the protoplanetary disk around HD 142527
• Subsonic Mechanical Alignment of Irregular Grains
• Grain Alignment and Polarized Emission from Magnetized T Tauri Disks
• Dust Polarization Toward Embedded Protostars in Ophiuchus with ALMA. II. IRAS 16293-2422
• Investigating dust trapping in transition disks with millimeter-wave polarization
• Non-linear Development of Secular Gravitational Instability in Protoplanetary Disks
• Millimeter-wave polarization due to grain alignment by the gas flow in protoplanetary disks

Cited by in corpus (15)

• Molecules with ALMA at Planet-forming Scales (MAPS) XIV: Revealing disk substructures in multi-wavelength continuum emission
• Dust Polarization Toward Embedded Protostars in Ophiuchus with ALMA. III. Survey Overview
• Radial variations in grain sizes and dust scale heights in the protoplanetary disk around HD 163296 revealed by ALMA polarization observation
• Porous Dust Particles in Protoplanetary Disks: Application to the HL Tau Disk
• Pebble drift and planetesimal formation in protoplanetary discs with embedded planets
• ALMA CN Zeeman Observations of AS 209: Limits on Magnetic Field Strength and Magnetically Driven Accretion Rate
• Solving grain size inconsistency between ALMA polarization and VLA continuum in the Ophiuchus IRS 48 protoplanetary disk
• Validating Scattering-Induced (Sub)millimeter Disk Polarization through the Spectral Index, Wavelength-Dependent Polarization Pattern, and Polarization Spectrum: The Case of HD 163296
• Polarized emission by aligned grains in the Mie regime : application to protoplanetary disks observed by ALMA
• Modeling of the ALMA HL Tau Polarization by Mixture of Grain Alignment and Self-scattering
• (Sub)millimeter Dust Polarization of Protoplanetary Disks from Scattering by Large Millimeter-Sized Irregular Grains
• Self-scattering on large, porous grains in protoplanetary disks with dust settling
• Discovery of Molecular Line Polarization in the Disk of TW Hya
• Thermal Emission and Scattering by Aligned Grains: Plane-Parallel Model and Application to Multiwavelength Polarization of the HL Tau Disk
• Wavelength-dependent far-infrared polarization of HL Tau observed with SOFIA/HAWC+