B-fields in Star-forming Region Observations (BISTRO): Magnetic Fields in the Filamentary Structures of Serpens Main
Authors: Kwon Woojin , Pattle Kate , Sadavoy Sarah , Hull Charles L. H. , Johnstone Doug , Ward-Thompson Derek , Francesco James Di , Koch Patrick M. , Furuya Ray , Doi Yasuo , Le Gouellec Valentin J. M. , Hwang Jihye , Lyo A-Ran , Soam Archana , Tang Xindi , Hoang Thiem , Kirchschlager Florian , Eswaraiah Chakali , Fanciullo Lapo , Kim Kyoung Hee , Onaka Takashi , Könyves Vera , Kang Ji-hyun , Lee 이 Chang Won 창원 , Tamura Motohide , Bastien Pierre , Hasegawa 長谷 Tetsuo 川哲夫 , Lai Shih-Ping , Qiu Keping , Berry David , Arzoumanian Doris , Bourke Tyler L. , Byun Do-Young , Chen Wen Ping , Chen Huei-Ru Vivien , Chen Mike , Chen Zhiwei , Ching 慶 Tao-Chung 道沖 , Cho Jungyeon , Choi Yunhee , Choi Minho , Chrysostomou Antonio , Chung Eun Jung , Coudé Simon , Dai Sophia , Diep Pham Ngoc , Duan Yan , Duan Hao-Yuan , Eden David , Fiege Jason , Fissel Laura M. , Franzmann Erica , Friberg Per , Friesen Rachel , Fuller Gary , Gledhill Tim , Graves Sarah , Greaves Jane , Griffin Matt , Gu Qilao , Han Ilseung , Hatchell Jennifer , Hayashi Saeko , Houde Martin , Inoue Tsuyoshi , Inutsuka Shu-ichiro , Iwasaki Kazunari , Jeong Il-Gyo , Kang Miju , Karoly Janik , Kataoka Akimasa , Kawabata Koji , Kemper Francisca , Kim Kee-Tae , Kim Gwanjeong , Kim Mi-Ryang , Kim Shinyoung , Kim Jongsoo , Kirk Jason , Kobayashi Masato I. N. , Kusune Takayoshi , Kwon Jungmi , Lacaille Kevin , Law Chi-Yan , Lee Chin-Fei , Lee Yong-Hee , Lee Hyeseung , Lee Jeong-Eun , Lee Sang-Sung , Li Dalei , Li Di , Li Hua-bai , Lin 林 Sheng-Jun 聖鈞 , Liu Sheng-Yuan , Liu Hong-Li , Liu 刘 Junhao 峻豪 , Liu 刘 Tie 铁 , Lu Xing , Mairs Steve , Matsumura 松村 Masafumi 雅文 , Matthews Brenda , Moriarty-Schieven Gerald , Nagata Tetsuya , Nakamura Fumitaka , Nakanishi Hiroyuki , Ngoc Nguyen Bich , Ohashi Nagayoshi , Park Geumsook , Parsons Harriet , Peretto Nicolas , Priestley Felix , Pyo Tae-Soo , Qian Lei , Rao Ramprasad , Rawlings Jonathan , Rawlings Mark G. , Retter Brendan , Richer John , Rigby Andrew , Saito Hiro , Savini Giorgio , Seta Masumichi , Shimajiri Yoshito , Shinnaga Hiroko , Tahani Mehrnoosh , Tang Ya-Wen , Tomisaka Kohji , Tram Le Ngoc , Tsukamoto Yusuke , Viti Serena , Wang Hongchi , Wang Jia-Wei , Whitworth Anthony , Wu Jintai , Xie 謝 Jinjin 津津 , Yen Hsi-Wei , Yoo Hyunju , Yuan Jinghua , Yun Hyeong-Sik , Zenko Tetsuya , Zhang Yapeng , Zhang Chuan-Peng , Zhang Guoyin , Zhou Jianjun , Zhu Lei , Looze Ilse de , André Philippe , Dowell C. Darren , Eyres Stewart , Falle Sam , Robitaille Jean-François , Loo Sven van 
Published: February 2022

Abstract
We present 850 μm polarimetric observations toward the Serpens Main molecular cloud obtained using the POL-2 polarimeter on the James Clerk Maxwell Telescope as part of the B-fields In STar-forming Region Observations survey. These observations probe the magnetic field morphology of the Serpens Main molecular cloud on about 6000 au scales, which consists of cores and six filaments with different physical properties such as density and star formation activity. Using the histogram of relative orientation (HRO) technique, we find that magnetic fields are parallel to filaments in less-dense filamentary structures where

N

H

2

<
0.93
×

10

22

cm−2 (magnetic fields perpendicular to density gradients), while they are perpendicular to filaments (magnetic fields parallel to density gradients) in dense filamentary structures with star formation activity. Moreover, applying the HRO technique to denser core regions, we find that magnetic field orientations change to become perpendicular to density gradients again at

N

H

2

≈
4.6
×

10

22

cm−2. This can be interpreted as a signature of core formation. At

N

H

2

≈
16
×

10

22

cm−2, magnetic fields change back to being parallel to density gradients once again, which can be understood to be due to magnetic fields being dragged in by infalling material. In addition, we estimate the magnetic field strengths of the filaments (B
POS = 60–300 μG)) using the Davis–Chandrasekhar–Fermi method and discuss whether the filaments are gravitationally unstable based on magnetic field and turbulence energy densities.