Resolving the Polarized Dust Emission of the Disk around the Massive Star Powering the HH 80-81 Radio Jet
Journal
Date Issued
2018
Author(s)
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.
•
•
Rao, R.
•
Rodríguez, L. F.
•
Torrelles, J. M.
Abstract
Here we present deep (16 μJy beam-1), 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.
Funding(s)
Volume
856
Issue
2
Start page
L27
Issn Identifier
0004-637X
Ads BibCode
2018ApJ...856L..27G
Rights
open.access
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