The JCMT BISTRO survey: alignment between outflows and magnetic fields in dense cores/clumps
Abstract
We compare the directions of molecular outflows of 62 low-mass Class 0 and I protostars in nearby (<450 pc) star-forming regions with the mean orientations of the magnetic fields on 0.05-0.5 pc scales in the dense cores/clumps where they are embedded. The magnetic field orientations were measured using the JCMT POL-2 data taken by the BISTRO-1 survey and from the archive. The outflow directions were observed with interferometers in the literature. The observed distribution of the angles between the outflows and the magnetic fields peaks between 15 and 35 degrees. After considering projection effects, our results could suggest that the outflows tend to be misaligned with the magnetic fields by 50+/-15 degrees in three-dimensional space and are less likely (but not ruled out) randomly oriented with respect to the magnetic fields. There is no correlation between the misalignment and the bolometric temperatures in our sample. In several sources, the small-scale (1000-3000 au) magnetic fields is more misaligned with the outflows than their large-scale magnetic fields, suggesting that the small-scale magnetic field has been twisted by the dynamics. In comparison with turbulent MHD simulations of core formation, our observational results are more consistent with models in which the energy densities in the magnetic field and the turbulence of the gas are comparable. Our results also suggest that the misalignment alone cannot sufficiently reduce the efficiency of magnetic braking to enable formation of the observed number of large Keplerian disks with sizes larger than 30-50 au.
Keywords
Cite
@article{arxiv.2011.06731,
title = {The JCMT BISTRO survey: alignment between outflows and magnetic fields in dense cores/clumps},
author = {Hsi-Wei Yen and Patrick M. Koch and Charles L. H. Hull and Derek Ward-Thompson and Pierre Bastien and Tetsuo Hasegawa and Woojin Kwon and Shih-Ping Lai and Keping Qiu and Tao-Chung Ching and Eun Jung Chung and Simon Coude and James Di Francesco and Pham Ngoc Diep and Yasuo Doi and Chakali Eswaraiah and Sam Falle and Gary Fuller and Ray S. Furuya and Ilseung Han and Jennifer Hatchell and Martin Houde and Shu-ichiro Inutsuka and Doug Johnstone and Ji-hyun Kang and Miju Kang and Kee-Tae Kim and Florian Kirchschlager and Jungmi Kwon and Chang Won Lee and Chin-Fei Lee and Hong-Li Liu and Tie Liu and A-Ran Lyo and Nagayoshi Ohashi and Takashi Onaka and Kate Pattle and Sarah Sadavoy and Hiro Saito and Hiroko Shinnaga and Archana Soam and Mehrnoosh Tahani and Motohide Tamura and Ya-Wen Tang and Xindi Tang and Chuan-Peng Zhang},
journal= {arXiv preprint arXiv:2011.06731},
year = {2021}
}
Comments
27 pages, 14 figures, Accepted by ApJ