ner_tags: O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O
tokens: polarized intensity (grayscale), and polarization position angle segments (red bars) in the GGD27 MM1 disk. Bottom panel: similar as before, but the color image showing the polarization fraction (here, the polarization position angle segments appear as black bars). In both panels, the contour levels are 3, 10, 50, 120, 200, and 400 K. The wedge shows the scale of the polarized intensity and polarization fraction. The synthesized beam is shown in the bottom-right corner of the panels. Note that the 120 K contour appears at the transition radius, with an almost null polarization ring, between two distinctive polarization patterns. The region inside the transition radius, R turn , (hereafter the inner disk) has a very low polarization level region. Thus, within this radius the polarization degree has a mean value of 0.56% and a standard deviation of 0.33%. In the left panel of Figure 4 , the histogram of the polarization position angles shows two main directions. Most of the angles are partially aligned with the minor axis (226), with an average direction of ∼36°. The other region arises from the northeast quadrant of the inner disk, and shows an average position angle of −38°. Figure 4. Left panel: histogram of the distribution of the polarization position angles for the disk’s inner region ( R 010). The dashed line indicates the position angle of the disk minor axis. Right panel: histogram of the differences between the polarization position angles and the disk azimuthal angles for the disk’s outer region ( R > 010). The outer disk (i.e., the region outside R turn ) has significantly higher polarization levels than the inner disk, with an average value of 4.0% and a standard deviation of 2.3%. 17 17 This has been measured in a region enclosed between R turn and the disk radius of R disk . The polarization position angles have a nearly azimuthal pattern (i.e., they follow a direction tangent to the iso-intensity contours of the Stokes I emission). At the position of each polarization position angle segment shown in Figure 3 , we have computed the expected tangent angle for an ellipse centered in the disk center that crosses this point. The right panel of Figure 4 shows the histogram of the difference between this tangent angle and the observed polarization angle. The average angle difference, 11°, is relatively small. This confirms the azimuthal pattern in the outer disk. 4. Discussion 4.1. The Optically Thick Disk around the Massive Protostar Powering the HH 80–81 Jet The brightness temperature of the disk dust emission reaches high values, up to ∼400 K, but it drops well below 10 K in the outskirts of the disk. This suggests that the inner part of the disk is optically thick and that the dust optical depth decreases with radius, becoming optically thin. A multi-line analysis of SO 2 , at scales of a few hundred au, indicates that the average kinetic temperature of the traced molecular gas is ∼120 K (Fernández-López et al. 2011b ).