Resolving the Polarized Dust Emission of the Disk around the Massive Star Powering the HH 80─81 Radio Jet

DOI: 
10.3847/2041-8213/aab76b
Publication date: 
01/04/2018
Main author: 
Girart, J. M.
IAA authors: 
Anglada, G.;Gómez, J. F.;Osorio, M.
Authors: 
Girart, J. M.;Fernández-López, M.;Li, Z. -Y.;Yang, H.;Estalella, R.;Anglada, G.;Áñez-López, N.;Busquet, G.;Carrasco-González, C.;Curiel, S.;Galvan-Madrid, R.;Gómez, J. F.;de Gregorio-Monsalvo, I.;Jiménez-Serra, I.;Krasnopolsky, R.;Martí, J.;Osorio, M.;Padovani, M.;Rao, R.;Rodríguez, L. F.;Torrelles, J. M.
Journal: 
The Astrophysical Journal
Refereed: 
Yes
Publication type: 
Article
Volume: 
856
Pages: 
L27
Abstract: 
Here we present deep (16 μJy beam<SUP>−1</SUP>), very high (40 mas) angular resolution 1.14 mm, polarimetric, Atacama Large Millimeter/submillimeter Array (ALMA) observations toward the massive protostar driving the HH 80─81 radio jet. The observations clearly resolve the disk oriented perpendicularly to the radio jet, with a radius of ≃0.″171 (∼291 au at 1.7 kpc distance). The continuum brightness temperature, the intensity profile, and the polarization properties clearly indicate that the disk is optically thick for a radius of R ≲ 170 au. The linear polarization of the dust emission is detected almost all along the disk, and its properties suggest that dust polarization is produced mainly by self-scattering. However, the polarization pattern presents a clear differentiation between the inner (optically thick) part of the disk and the outer (optically thin) region of the disk, with a sharp transition that occurs at a radius of ∼0.″1 (∼170 au). The polarization characteristics of the inner disk suggest that dust settling has not occurred yet with a maximum dust grain size between 50 and 500 μm. The outer part of the disk has a clear azimuthal pattern but with a significantly higher polarization fraction compared to the inner disk. This pattern is broadly consistent with the self-scattering of a radiation field that is beamed radially outward, as expected in the optically thin outer region, although contribution from non-spherical grains aligned with respect to the radiative flux cannot be excluded.
Database: 
ADS
SCOPUS
URL: 
https://ui.adsabs.harvard.edu/#abs/2018ApJ...856L..27G/abstract
ADS Bibcode: 
2018ApJ...856L..27G
Keywords: 
accretion;accretion disks;ISM: individual objects: GGD27;HH 80─81;IRAS 18162-2048;stars: formation;Astrophysics - Solar and Stellar Astrophysics;Astrophysics - Astrophysics of Galaxies