2018/03/16 by J. M. Girart, M. Fernandez-Lopez, M. Fernández-López +26 · 69 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Brightness #Cosmic dust #Dust and Plasma Wave Phenomena #Linear polarization #Perpendicular #Polarization (electrochemistry) #Protostar #RADIUS #Radiation #Radiative transfer #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.3847/2041-8213/aab76b
published in The Astrophysical Journal Letters 856(2), L27 (IOP Publishing) · Accepted for publication in the Astrophysical Journal Letters
arxiv created 2018/03/16 · openalex publication_date 2018/03/28 · openalex created_date 2018/03/29 · arxiv updated 2018/04/11 · openalex updated_date 2026/08/05
Abstract Here we present deep (16 μ Jy 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 μ m. 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.