Magnetic Fields toward Ophiuchus-B Derived from SCUBA-2 Polarization Measurements

Soam, Archana; Pattle, Kate; Ward-Thompson, Derek; Lee, Chang Won; Sadavoy, Sarah; Koch, Patrick M.; Kim, Gwanjeong; Kwon, Jungmi; Kwon, Woojin; Arzoumanian, D.; Berry, D. S.; Hoang, Thiem; Tamura, Motohide; Lee, Sang-Sung; Liu, Tie; Kim, Kee‐Tae; Johnstone, Doug; Nakamura, Fúmitaka; Lyo, A-Ran; Onaka, Takashi; Kim, Jong-Soo; Furuya, Ray S.; Hasegawa, Tetsuo; Lai, Shih-Ping; Bastien, Pierre; Chung, Eun Jung; Kim, Shinyoung; Parsons, Harriet; Rawlings, Mark G.; Mairs, Steve; Graves, Sarah; Robitaille, Jean-Franois; Liu, Hongli; Whitworth, Anthony Peter; Eswaraiah, Chakali; Rao, Ramprasad; Yoo, Hyunju; Houde, Martin; Kang, Ji-hyun; Doi, Yasuo; Choi, Minho; Kang, Miju; Coudé, Simon; Li, Hua-bai; Matsumura, Masatoshi; Matthews, Brenda C.; Pon, Andy; Francesco, James Di; Hayashi, Saeko S.; Kawabata, Koji S.; Inutsuka, Shu‐ichiro; Qiu, Keping; Franzmann, Erica; Friberg, Per; Greaves, J. S.; Kirk, J. M.; Li, Di; Shinnaga, Hiroko; Loo, S. Van; Aso, Yusuke; Byun, Doyoung; Chen, Huei-Ru Vivien; Chen, Mike C.-Y.; Chen, Wen-Ping; Ching, Tao-Chung; Cho, Jungyeon; Chrysostomou, A.; Drabek-Maunder, E.; Eyres, S. P. S.; Fiege, Jason D.; Friesen, Rachel; Fuller, G. A.; Gledhill, Tim; Griffin, Matt; Gu, Qilao; Hatchell, Jennifer; Holland, W. S.; Inoue, Tsuyoshi; Iwasaki, Kazunari; Jeong, Il-Gyo; Kang, Sung-Ju; Kemper, F.; Kim, Kyoung Hee; Kim, Mi-Ryang; Lacaille, Kevin; Lee, Jeong Eun; Li, Dalei; Liu, Junhao; Liu, Sheng-Yuan; Moriarty‐Schieven, G. H.; Nakanishi, Hiroyuki; Ohashi, Nagayoshi; Peretto, N.; Pyo, Tae‐Soo; Qian, Lei; Retter, Brendan; Richer, J. S.; Rigby, Andrew; Savini, G.; Scaife, Anna M. M.; Tang, Ya-Wen; Tomisaka, Kohji; Wang, Hongchi; Wang, Jiawei; Yen, Hsi-Wei; Yuan, Jinghua; Zhang, Chuan-Peng; Zhang, Guoyin; Zhou, Jianjun; Zhu, Lei; André, P.; Dowell, C. D.; Falle, S. A. E. G.; Tsukamoto, Yusuke; Kanamori, Yoshihiro; Kataoka, Akimasa; Kobayashi, Masato I. N.; Nagata, T.; Saito, Hiro; Seta, Masumichi; Hwang, Jihye; Han, Ilseung; Lee, Hyeseung; Zenko, Tetsuya

doi:10.3847/1538-4357/aac4a6

Cited by 56 publications

(48 citation statements)

References 82 publications

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“…This value is in the lower end of the range found on similar spatial scales performed in star forming regions for example with the JCMT telescope (see e.g. Crutcher et al 2004;Kwon et al 2018;Soam et al 2018;Liu et al 2019), where B-strengths of 80 − 5000 µG have been reported.…”

Section: Discussionsupporting

confidence: 51%

Magnetic properties of the protostellar core IRAS 15398-3359

Redaelli

Alves

Santos

et al. 2019

A&A

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Context. Magnetic fields can affect significantly the star formation process. The theory of the magnetically-driven collapse in a uniform field predicts that initially the contraction happens along the field lines. When the gravitational pull grows strong enough, the magnetic field lines pinch inwards, giving rise to a characteristic hourglass shape. Aims. We investigate the magnetic field structure of a young Class 0 object, IRAS 15398-3359, embedded in the Lupus I cloud. Previous observations at large scales suggest that this source evolved in an highly magnetised environment. This object thus appears an ideal candidate to study the magnetically driven core collapse in the low-mass regime. Methods. We have performed polarisation observations of IRAS 15398-3359 at 214 µm using the SOFIA/HAWC+ instrument, thus tracing the linearly polarised thermal emission of cold dust. Results. Our data unveil a significant bend of the magnetic field lines due to the gravitational pull. The magnetic field appears ordered and aligned with the large-scale B-field of the cloud and with the outflow direction. We estimate a magnetic field strength of B = 78 µG, expected to be accurate within a factor of two. The measured mass-to-flux parameter is λ = 0.95, indicating that the core is in a transcritical regime.

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Section: Discussionsupporting

confidence: 51%

Magnetic properties of the protostellar core IRAS 15398-3359

Redaelli

Alves

Santos

et al. 2019

A&A

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“…The power-law index in L1521F is found to be similar to the index α ∼ -0.9 in ρ Ophiuchus B (Soam et al, 2018) and more identical to α ∼ -0.8 in ρ Ophiuchus A (Kwon et al, 2018). A recent study by Seifried et al (2018) explored the reasons of the observed depolarization in the center of molecular clouds using dust polarization maps of 3D magnetohydrodynamical (MHD) simulations.…”

Section: Depolarizationmentioning

confidence: 69%

“…Starlink tasks such as calcqu and makemap were used in the reduction process. The detailed procedure to reduce the data and to produce polarization catalog is explained in Kwon et al (2018) and Soam et al (2018). We adopted slightly different reduction procedure by using an additional parameter skyloop in pol2map setting pixel size as 12 ′′ .…”

Section: Data Acquisition and Reduction Techniquesmentioning

confidence: 99%

First Sub-parsec-scale Mapping of Magnetic Fields in the Vicinity of a Very-low-luminosity Object, L1521F-IRS

Soam

Lee

Andersson

et al. 2019

ApJ

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L1521F is found to be forming multiple cores and it is cited as an example of the densest core with an embedded VeLLO in a highly dynamical environment. We present the core-scale magnetic fields (B-fields) in the near vicinity of the VeLLO L1521F-IRS using submm polarization measurements at 850 µm using JCMT POL-2. This is the first attempt to use high-sensitivity observations to map the sub-parsec scale B-fields in a core with a VeLLO. The B-fields are ordered and very well connected to the parsec-scale field geometry seen in our earlier optical polarization observations and the large-scale structure seen in Planck dust polarization. The core scale B-field strength estimated using Davis-Chandrasekhar-Fermi relation is 330 ± 100 µG which is more than ten times of the value we obtained in the envelope (envelope in this paper is "core envelope"). This indicates that B-fields are getting stronger on smaller scales. The magnetic energies are found to be 1 to 2 orders of magnitude higher than non-thermal kinetic energies in the envelope and core. This suggests that magnetic fields are more important than turbulence in the energy budget of L1521F. The mass-to-flux ratio of 2.3±0.7 suggests that the core is magnetically-supercritical. The degree of polarization is steadily decreasing towards the denser part of the core with a power law slope of -0.86.

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“…The ρ Oph A clump has been observed in dust polarization at 89 µm and 154 µm with SOFIA/HAWC+ (Santos et al 2019) and at 850 µm with JCMT/POL-2 (Kwon et al 2018), and the Oph B and C clumps have been observed at 850 µm (Soam et al 2018;Liu et al 2019). For Oph A, the 214-850 µm data show largely consistent, well-ordered polarization across Oph A such that the inferred magnetic field appears to be mostly uniform.…”

Section: Comparison With Magnetic Fields On Clump Scalesmentioning

confidence: 97%

Dust Polarization toward Embedded Protostars in Ophiuchus with ALMA. III. Survey Overview

Sadavoy

Stephens

Myers

et al. 2019

ApJS

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We present 0.25 resolution (35 au) ALMA 1.3 mm dust polarization observations for 37 young stellar objects (YSOs) in the Ophiuchus molecular cloud. These data encompass all the embedded protostars in the cloud and several Flat and Class II objects to produce the largest, homogeneous study of dust polarization on disk scales to date. The goal of this study is to study dust polarization morphologies down to disk scales. We find that 14/37 (38%) of the observed YSOs are detected in polarization at our sensitivity. Nine of these sources have uniform polarization angles and four sources have azimuthal polarization structure. We find that the sources with uniform polarization tend to have steeper inclinations (> 60 • ) than those with azimuthal polarization (< 60 • ). Overall, the majority (9/14) of the detected sources have polarization morphologies and disk properties consistent with dust self-scattering processes in optically thick disks. The remaining sources may be instead tracing magnetic fields. Their inferred field directions from rotating the polarization vectors by 90 • are mainly poloidal or hourglass shaped. We find no evidence of a strong toroidal field component toward any of our disks. For the 23 YSOs that are undetected in polarization, roughly half of them have 3-sigma upper limits of < 2%. These sources also tend to have inclinations < 60 • and they are generally compact. Since lower inclination sources tend to have azimuthal polarization, these YSOs may be undetected in polarization due to unresolved polarization structure within our beam. We propose that disks with inclinations > 60 • are the best candidates for future polarization studies of dust selfscattering as these systems will generally show uniform polarization vectors that do not require very high resolution to resolve. We release the continuum and polarization images for all the sources with this publication. Data from the entire survey can be obtained from Dataverse. † Hubble Fellow

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Magnetic Fields toward Ophiuchus-B Derived from SCUBA-2 Polarization Measurements

Cited by 56 publications

References 82 publications

Magnetic properties of the protostellar core IRAS 15398-3359

Magnetic properties of the protostellar core IRAS 15398-3359

First Sub-parsec-scale Mapping of Magnetic Fields in the Vicinity of a Very-low-luminosity Object, L1521F-IRS

Dust Polarization toward Embedded Protostars in Ophiuchus with ALMA. III. Survey Overview

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