ALMA Observations of Polarized Emission toward the CW Tau and DG Tau Protoplanetary Disks: Constraints on Dust Grain Growth and Settling

Files in This Item:
File Description SizeFormat 
1809.02559.pdf768.04 kBAdobe PDFDownload
Title: ALMA Observations of Polarized Emission toward the CW Tau and DG Tau Protoplanetary Disks: Constraints on Dust Grain Growth and Settling
Authors: Bacciotti, FrancescaGirart, Josep MiquelPadovani, MarcoCoffey, Deirdreet al.
Permanent link:
Date: 1-Oct-2018
Online since: 2019-10-15T15:07:30Z
Abstract: We present polarimetric data of CW Tau and DG Tau, two well-known Class II disk/jet systems, obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) at 870 μm and 0.″2 average resolution. In CW Tau, the total and polarized emission are both smooth and symmetric, with polarization angles almost parallel to the minor axis of the projected disk. In contrast, DG Tau displays a structured polarized emission, with an elongated brighter region in the disk's near side and a belt-like feature beyond about 0.″3 from the source. At the same time, the total intensity is spatially smooth, with no features. The polarization pattern, almost parallel to the minor axis in the inner region, becomes azimuthal in the outer belt, possibly because of a drop in optical depth. The polarization fraction has average values of 1.2% in CW Tau and 0.4% in DG Tau. Our results are consistent with polarization from self-scattering of the dust thermal emission. In this hypothesis, the maximum size of the grains contributing to polarization is in the range 100-150 μm for CW Tau and 50-70 μm for DG Tau. The polarization maps combined with dust opacity estimates indicate that these grains are distributed in a geometrically thin layer in CW Tau, representing a settling in the disk midplane. Meanwhile, such settling is not yet apparent for DG Tau. These results advocate polarization studies as a fundamental complement to total emission observations, in investigations of the structure and the evolution of protoplanetary disks.
Funding Details: European Commission Horizon 2020
metadata.dc.description.othersponsorship: MINECO (Spain)
Italian Ministero dell’Istruzione, Università e Ricerca
Deutsche Forschungs-gemeinschaft (DFG; German Research Foundation)
Type of material: Journal Article
Publisher: IOP Publishing
Journal: Astrophysical Journal Letters
Volume: 865
Issue: 2
Copyright (published version): 2018 The American Astronomical Society
Keywords: ISMJetsOutflowsPolarizationProtoplanetary disks
DOI: 10.3847/2041-8213/aadf87
Language: en
Status of Item: Not peer reviewed
Appears in Collections:Physics Research Collection

Show full item record

Citations 20

Last Week
Last month
checked on Jan 16, 2020

Page view(s)

Last Week
Last month
checked on Jan 22, 2020


checked on Jan 22, 2020

Google ScholarTM



This item is available under the Attribution-NonCommercial-NoDerivs 3.0 Ireland. No item may be reproduced for commercial purposes. For other possible restrictions on use please refer to the publisher's URL where this is made available, or to notes contained in the item itself. Other terms may apply.