The JCMT BISTRO Survey: The Magnetic Field of the Barnard 1 Star-forming Region
Authors: Coudé Simon , Bastien Pierre , Houde Martin , Sadavoy Sarah , Friesen Rachel , Francesco James Di , Johnstone Doug , Mairs Steve , Hasegawa Tetsuo , Kwon Woojin , Lai Shih-Ping , Qiu Keping , Ward-Thompson Derek , Berry David , Chen Michael Chun-Yuan , Fiege Jason , Franzmann Erica , Hatchell Jennifer , Lacaille Kevin , Matthews Brenda C. , Moriarty-Schieven Gerald H. , Pon Andy , André Philippe , Arzoumanian Doris , Aso Yusuke , Byun Do-Young , Eswaraiah Chakali , Chen Huei-Ru , Chen Wen Ping , Ching Tao-Chung , Cho Jungyeon , Choi Minho , Chrysostomou Antonio , Chung Eun Jung , Doi Yasuo , Drabek-Maunder Emily , Dowell C. Darren , Eyres Stewart P. S. , Falle Sam , Friberg Per , Fuller Gary , Furuya Ray S. , Gledhill Tim , Graves Sarah F. , Greaves Jane S. , Griffin Matt J. , Gu Qilao , Hayashi Saeko S. , Hoang Thiem , Holland Wayne , Inoue Tsuyoshi , Inutsuka Shu-ichiro , Iwasaki Kazunari , Jeong Il-Gyo , Kanamori Yoshihiro , Kataoka Akimasa , Kang Ji-hyun , Kang Miju , Kang Sung-ju , Kawabata Koji S. , Kemper Francisca , Kim Gwanjeong , Kim Jongsoo , Kim Kee-Tae , Kim Kyoung Hee , Kim Mi-Ryang , Kim Shinyoung , Kirk Jason M. , Kobayashi Masato I. N. , Koch Patrick M. , Kwon Jungmi , Lee Jeong-Eun , Lee Chang Won , Lee Sang-Sung , Li Dalei , Li Di , Li Hua-bai , Liu Hong-Li , Liu Junhao , Liu Sheng-Yuan , Liu Tie , Loo Sven van , Lyo A-Ran , Matsumura Masafumi , Nagata Tetsuya , Nakamura Fumitaka , Nakanishi Hiroyuki , Ohashi Nagayoshi , Onaka Takashi , Parsons Harriet , Pattle Kate , Peretto Nicolas , Pyo Tae-Soo , Qian Lei , Rao Ramprasad , Rawlings Mark G. , Retter Brendan , Richer John , Rigby Andrew , Robitaille Jean-François , Saito Hiro , Savini Giorgio , Scaife Anna M. M. , Seta Masumichi , Shinnaga Hiroko , Soam Archana , Tamura Motohide , Tang Ya-Wen , Tomisaka Kohji , Tsukamoto Yusuke , Wang Hongchi , Wang Jia-Wei , Whitworth Anthony P. , Yen Hsi-Wei , Yoo Hyunju , Yuan Jinghua , Zenko Tetsuya , Zhang Chuan-Peng , Zhang Guoyin , Zhou Jianjun , Zhu Lei ,   The B-fields In STar-forming Regions Observations (BISTRO) Collaboration
Published: May 2019

Abstract
We present the POL-2 850 μm linear polarization map of the Barnard 1 clump in the Perseus molecular cloud complex from the B-fields In STar-forming Region Observations survey at the James Clerk Maxwell Telescope. We find a trend of decreasing polarization fraction as a function of total intensity, which we link to depolarization effects toward higher-density regions of the cloud. We then use the polarization data at 850 μm to infer the plane-of-sky orientation of the large-scale magnetic field in Barnard 1. This magnetic field runs north–south across most of the cloud, with the exception of B1-c, where it turns more east–west. From the dispersion of polarization angles, we calculate a turbulence correlation length of 5.0 ± 2.″5 (1500 au) and a turbulent-to-total magnetic energy ratio of 0.5 ± 0.3 inside the cloud. We combine this turbulent-to-total magnetic energy ratio with observations of NH3 molecular lines from the Green Bank Ammonia Survey to estimate the strength of the plane-of-sky component of the magnetic field through the Davis–Chandrasekhar–Fermi method. With a plane-of-sky amplitude of 120 ± 60 μG and a criticality criterion λ

c
= 3.0 ± 1.5, we find that Barnard 1 is a supercritical molecular cloud with a magnetic field nearly dominated by its turbulent component.