2021MNRAS.503.3414P -
Mon. Not. R. Astron. Soc., 503, 3414-3433 (2021/May-3)
OMC-1 dust polarization in ALMA Band 7: diagnosing grain alignment mechanisms in the vicinity of Orion Source I.
PATTLE K., LAI S.-P., WRIGHT M., COUDE S., PLAMBECK R., HOANG T., TANG Y.-W., BASTIEN P., ESWARAIAH C., FURUYA R.S., HWANG J., INUTSUKA S.-I., KIM K.-T., KIRCHSCHLAGER F., KWON W., LEE C.W., LIU S.-Y., LYO A., OHASHI N., RAWLINGS M.G., TAHANI M., TAMURA M., SOAM A., WANG J.-W. and WARD-THOMPSON D.
Abstract (from CDS):
We present ALMA Band 7 polarization observations of the OMC-1 region of the Orion molecular cloud. We find that the polarization pattern observed in the region is likely to have been significantly altered by the radiation field of the >104 L☉ high-mass protostar Orion Source I. In the protostar's optically thick disc, polarization is likely to arise from dust self-scattering. In material to the south of Source I - previously identified as a region of 'anomalous' polarization emission - we observe a polarization geometry concentric around Source I. We demonstrate that Source I's extreme luminosity may be sufficient to make the radiative precession time-scale shorter than the Larmor time-scale for moderately large grains (> 0.005-0.1 µm), causing them to precess around the radiation anisotropy vector (k-RATs) rather than the magnetic field direction (B-RATs). This requires relatively unobscured emission from Source I, supporting the hypothesis that emission in this region arises from the cavity wall of the Source I outflow. This is one of the first times that evidence for k-RAT alignment has been found outside of a protostellar disc or AGB star envelope. Alternatively, the grains may remain aligned by B-RATs and trace gas infall on to the Main Ridge. Elsewhere, we largely find the magnetic field geometry to be radial around the BN/KL explosion centre, consistent with previous observations. However, in the Main Ridge, the magnetic field geometry appears to remain consistent with the larger-scale magnetic field, perhaps indicative of the ability of the dense Ridge to resist disruption by the BN/KL explosion.
Abstract Copyright:
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society
Journal keyword(s):
techniques: polarimetric - stars: formation - ISM: dust, extinction - ISM: magnetic fields - submillimetre: ISM
Simbad objects:
10
Full paper
View the references in ADS
To bookmark this query, right click on this link: simbad:2021MNRAS.503.3414P and select 'bookmark this link' or equivalent in the popup menu